Agrivoltaic Systems Design and Assessment: A Critical Review, and a Descriptive Model towards a Sustainable Landscape Vision (Three-Dimensional Agrivoltaic Patterns)

Abstract

As an answer to the increasing demand for photovoltaics as a key element in the energy transition strategy of many countries—which entails land use issues, as well as concerns regarding landscape transformation, biodiversity, ecosystems and human well-being—new approaches and market segments have emerged that consider integrated perspectives. Among these, agrivoltaics is emerging as very promising for allowing benefits in the food–energy (and water) nexus. Demonstrative projects are developing worldwide, and experience with varied design solutions suitable for the scale up to commercial scale is being gathered based primarily on efficiency considerations; nevertheless, it is unquestionable that with the increase in the size, from the demonstration to the commercial scale, attention has to be paid to ecological impacts associated to specific design choices, and namely to those related to landscape transformation issues. This study reviews and analyzes the technological and spatial design options that have become available to date implementing a rigorous, comprehensive analysis based on the most updated knowledge in the field, and proposes a thorough methodology based on design and performance parameters that enable us to define the main attributes of the system from a trans-disciplinary perspective.

Full text

sustainability
Review
Agrivoltaic Systems Design and Assessment: A Critical Review,
and a Descriptive Model towards a Sustainable Landscape
Vision (Three-Dimensional Agrivoltaic Patterns)
Carlos Toledo and Alessandra Scognamiglio *


Citation: Toledo, C.; Scognamiglio,
A. Agrivoltaic Systems Design and
Assessment: A Critical Review, and a
Descriptive Model towards a
Sustainable Landscape Vision
(Three-Dimensional Agrivoltaic
Patterns). Sustainability 2021,13, 6871.
https://doi.org/10.3390/su13126871
Academic Editor: Andrea Colantoni
Received: 29 May 2021
Accepted: 15 June 2021
Published: 17 June 2021
Publisher’s Note: MDPI stays neutral
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Copyright: © 2021 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
Italian National Agency for New Technologies, Energy and Sustainable Economic Development, ENEA,
Centro Ricerche Portici, Largo Enrico Fermi 1, 80055 Portici, Italy; agrivoltaics.project@enea.it
*Correspondence: alessandra.scognamiglio@enea.it; Tel.: +39-081-772-3304
Abstract:
As an answer to the increasing demand for photovoltaics as a key element in the energy
transition strategy of many countries—which entails land use issues, as well as concerns regarding
landscape transformation, biodiversity, ecosystems and human well-being—new approaches and
market segments have emerged that consider integrated perspectives. Among these, agrivoltaics is
emerging as very promising for allowing benefits in the food–energy (and water) nexus. Demon-
strative projects are developing worldwide, and experience with varied design solutions suitable
for the scale up to commercial scale is being gathered based primarily on efficiency considerations;
nevertheless, it is unquestionable that with the increase in the size, from the demonstration to the
commercial scale, attention has to be paid to ecological impacts associated to specific design choices,
and namely to those related to landscape transformation issues. This study reviews and analyzes
the technological and spatial design options that have become available to date implementing a
rigorous, comprehensive analysis based on the most updated knowledge in the field, and proposes a
thorough methodology based on design and performance parameters that enable us to define the
main attributes of the system from a trans-disciplinary perspective.
Keywords:
agrivoltaics; land use; photovoltaic design assessment; landscape; PV greenhouse; PV
pattern; integrated photovoltaics
Content
1. Introduction
1
2. Materials and Methods
4
3. State of art
5
3.1. Current design solution and technologies
5
3.2. Further agri-PV integrated applications
11
3.3. Relevant design parameters and performance metrics
11
3.3.1. Height of the modules from the ground
11
3.3.2. Spatial configuration of PV and type of crops
12
3.3.3. Performance metrics
14
4. A Trans-Disciplinary Cognitive Framework for the Design and Assessment of Agrivoltaics
15
4.1 Innovative three-dimensional patterns for improved ecological performances
15
4.2 A new landscape oriented descriptive model
17
4.2.1 On ground photovoltaics + open-field crops: The agrivoltaic pattern
19
4.2.2 Greenhouses (envelope integrated PV + protected crops)
25
4.3 Three-dimensional agrivoltaic patterns and related metrics
29
5. Conclusions
32
References
34
1. Introduction
Thanks to its modularity, decreasing cost, lifespan and efficiency improvements, pho-
tovoltaic (PV) technology is playing a key role in the transition to low-carbon economies.
Sustainability 2021,13, 6871. https://doi.org/10.3390/su13126871 https://www.mdpi.com/journal/sustainability

Sustainability 2021,13, 6871 2 of 38
Nowadays, however, land-based PV farms compete with food production for land alloca-
tion. Therefore, the number of innovative solutions for implementing PV while reducing
the related land use are becoming increasingly relevant. Building integrated photovoltaics
(BIPV) (use of existing building surfaces), floating PV (use of existing water surfaces) or
agrivoltaic systems (APV) (double use of land for food and energy) are some of these new
examples. They represent a strategic part of the future vision, with a huge potential driven
by the growing shift towards renewable energy sources.
In recent years, agrivoltaic systems have been the subject of numerous studies due
to their potential in the food–energy nexus. Demonstrative projects with new conceptual
designs based on PV modules for covering open fields have shown promising results
through optimizing light availability while reducing the need for irrigation and protecting
from extreme weather phenomena. APV denotes sharing the sunlight for co-production
of food and energy on the same piece of land; therefore, designs must overcome, as far
as possible, physical constrains of covering crops with photovoltaic modules in order to
alleviate the reduction in crop profitability. Some examples of the main issues related to
the use of co-located PV on cropland and the solutions commonly proposed to solve them
are shown in Table 1.
In parallel to the development of the new field-tested designs, the continuously
scientific progress in PV has extended the range of design solutions by using different
technologies which optimize the light absorption of the modules in different regions of
the light spectrum, so that the light resource can be shared for both purposes: energy
generation and crop growth. In this regard, success of experiences implementing PV in
greenhouses (protected fields) has shown technical feasibility in real operating conditions.
Just as Table 1summarizes the main problems of integrating PV modules in open fields
together with the solutions from two perspectives, design and technology, Table 2shows
them for greenhouses.
As can be seen, APV does not follow classical PV system design practices where
parameters such as tilt and orientation angles are optimized to maximize electricity pro-
duction choosing slopes close to the latitude and orientations facing the equator. Moving
PV to include farm activities is an ongoing challenge since energy performance sometimes
conflicts with optimal agricultural development and landscape preservation issues, and
thus involves multiple design adaptations according to the local climate conditions, crop
type, energy needs and landform. A new list of requirements must be addressed to ensure
and understand the tight connection between energy, food production and space. This
paper therefore aims to analyze the different design possibilities that focus on the energy
performance of the PV system, extending to agriculture objectives and presenting an origi-
nal contribution in the cognitive trans-disciplinary approach for describing and classifying
the agrivoltaic system, which harmonizes different disciplinary issues in a unique vision,
making room to consider landscape issues.
The article is organized as follows. Section 2presents the research method to describe
how the literature review was conducted. Section 3gives an overview of the current design
solutions and technologies used in agrivoltaic systems based on the literature and current
practices. In Section 4, the new inclusive approach to describe an agrivoltaic system is
presented and discussed. Finally, main conclusions are presented in Section 5.

Sustainability 2021,13, 6871 3 of 38
Table 1. Barriers and solutions to implementation of agrivoltaics in open-field systems.
Topic Design Related Solution Technology Related Solution
Minimizing shadows on crops
(biomass yield)
Optimal design:
Distance between the arrays of modules
(the stripes)Distance of the modules from
the ground
Sun-tracking systems
Semi-transparent PV modules (by
spacing PV cells)
Light-selective PV devices
Maximizing electric energy generation
Optimal planning:
Avoiding sharing losses from
surrounding elements (structures,
buildings, trees, inter-row shading of the
PV modules should be minimized)
Highly efficient systems
(e.g., sun-tracking systems)
Highly efficiency modules or
technologies (e.g., bifacial module
technology)
Optimal design:
Azimuth facing equator and tilt close to
latitude
Social acceptance (landscape dimension)
Optimal landscape design:
Pattern of PV arrays aligned to the parcel
Natural fences and low height structures
to minimize visual disturbance
Use of marginal areas
Removable systems
New materials for structure
Optimal design:
Different tilt, azimuth and height to
reproduces the orography of the land
New business models:
Higher economic efficiency per land unit
(farmer perspective)
Benefits for local economy and
employment (tourism,
local recreation, etc.)
Table 2. Technical barriers and solutions to implementation of agrivoltaics in greenhouses.
Topic Design Related Solution Technology Related Solution
Minimizing shadows on crops
(biomass yield)
Different layouts to homogenize the
distribution of the light inside the
greenhouse
Increase the gutter height of the
greenhouse
Dynamic systems
Semi-transparent PV modules (by
spacing PV cells or using
semi-transparent PV layers)
Minimizing the loss of PAR
(Photosynthetically active radiation) Use of colored layers
Spectral selective PV devices by selective
focus different wavelengths of the solar
spectrum on plants and
modulesLuminescent solar concentrator
technology (LSC)
Maximizing electric energy generation
Optimal design for energy generation:
Maximum energy intensity (dense
pattern of the PV modules) with no
shading effects on the modules
Optimal positioning of the modules (tilt
and azimuth angles of the roof)
Use of high efficiency PV systems, or
high efficiency PV modules (such as
bifacial modules)
Microclimatic issues (temperature and
humidity conditions inside the
greenhouse)
Ventilation (natural through vents)
Orientation (sun direction along the year)
Location (climate)
Highly efficient heating, ventilation and
air conditioning systems
Artificial light
Social acceptance
Designing the greenhouse for an optimal
visual performance (e.g., high level of
integration of the greenhouse in the
landscape, and of the modules in the
greenhouse envelope)
Appropriate choice of the PV
technologies allowing for an increased
visual performance (size, shape, color
and texture)

Sustainability 2021,13, 6871 4 of 38
2. Materials and Methods
A comprehensive review process was conducted by using Web of Science (WoS) (Clar-
ivate Analytics, https://apps.webofknowledge.com (accessed on 7 December 2020)) and
Scopus (Elsevier, https://www.scopus.com (accessed on 7 December 2020)). Peer-reviewed
literature databases where highly cited documents written in English and published up to
the date were consulted for the analysis. The following categories were considered: journal
publication (article or review) and conference paper. The keywords for the search engines
are listed as follows, including the different terminologies for the concept:
•“Agrophotovoltaics” (APV)—German research context
•“Agrivoltaics systems/array” (AVS/AVA)—French and US research context
•“Photovoltaic agriculture”—Chinese context
•“Solar sharing”—Japanese context
•“Photovoltaic or solar greenhouse” (PVG)
•“Agro-PV” or “agri-PV”
In addition to academic research papers, and in order to include the current research
development of agrivoltaics systems, the search was extended to outstanding demonstra-
tion projects and commercial-scale plants from the industry and relevant international
conferences in the field.
The academic papers were then reviewed to select those that follow the criteria of
“dual functionality” of generating electricity and serve a specific and integral purpose. In
this case, solutions which consider synergies between agriculture and photovoltaics.
Therefore, PV systems that are in “co-existence” with agricultural land and prioritize
farming activities were considered (It should be noted that publications which focus on key
saving strategies and climate control technologies for greenhouses using PV technology
were excluded in this research. We included only PV solutions which strategically were
used to provide electricity without substantially affecting crop quality or yield).
In total, 195 academic papers were identified. Upon reviewing the detail information
in the academic papers, there are three application areas that are being actively researched:
1. PV + open-field crops
2. PV + protected crops (photovoltaic greenhouses, PVGs)
3.
PV technology with innovative solutions designed to optimize the light transmission
(amount and spectral quality) increasing the compatibility between PV
and agriculture
.
Two scales are distinguished: the system scale (dynamic solutions) and the module
scale (enhances light transmittance through PV devices).
The literature review shows the increase in studies related to the topic in recent years,
as shown Figure 1a, while Figure 1b shows the special interest of the scientific community
in PV systems applied to greenhouses.
Sustainability 2021, 13, 6871 5 of 42
(a) Number of relevant academic papers published yearly (b) Publications by research areas
Figure 1. Literature review analysis.
3. State of Art
3.1. Current Design Solution and Technologies
The concept of a dual-use approach for both solar photovoltaic power as well as ag-
ricultural production was theoretically conceived by Goetzberger and Zastrow at the
Fraunhofer Institute (Germany) in 1981 [1]. They proposed to elevate the structure (by
about 2 m) and the distance between rows (about 3 times the height of the modules) to
achieve uniform radiation on the ground while at the same time that allow the moving of
mechanized agricultural equipment. In 2004, Japanese engineer Akira Nagashima devel-
oped the first agrivoltaic system (here referred to as “solar sharing”) using a structure
similar to a garden pergola [2]. Nagashima designed diverse test fields with different
shadowing rates based on the concept of the light saturation point of each crop (plants
only employ a small percentage of incident sunlight (between 3% and 6% of total solar
radiation) to accomplish their maximum rate of photosynthesis) with the idea of sharing
the excess of solar radiation with PV systems to generate electricity. Graphical represen-
tations of both proposed solutions are presented in Figure 2.
Figure 2. First models of agrivoltaic systems: co-located agriculture and solar photovoltaic (APV). © Goetzberger and
Zastrow [1] (a), A. Nagashima [3] (b).
0
5
10
15
20
25
30
35
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
Publications
Year
29%
47%
24%
Open field
Innovative device
PV greenhouse
Figure 1. Literature review analysis.

Sustainability 2021,13, 6871 5 of 38
3. State of Art
3.1. Current Design Solution and Technologies
The concept of a dual-use approach for both solar photovoltaic power as well as
agricultural production was theoretically conceived by Goetzberger and Zastrow at the
Fraunhofer Institute (Germany) in 1981 [
1
]. They proposed to elevate the structure (by
about 2 m) and the distance between rows (about 3 times the height of the modules) to
achieve uniform radiation on the ground while at the same time that allow the moving
of mechanized agricultural equipment. In 2004, Japanese engineer Akira Nagashima
developed the first agrivoltaic system (here referred to as “solar sharing”) using a structure
similar to a garden pergola [
2
]. Nagashima designed diverse test fields with different
shadowing rates based on the concept of the light saturation point of each crop (plants only
employ a small percentage of incident sunlight (between 3% and 6% of total solar radiation)
to accomplish their maximum rate of photosynthesis) with the idea of sharing the excess of
solar radiation with PV systems to generate electricity. Graphical representations of both
proposed solutions are presented in Figure 2.
Sustainability 2021, 13, 6871 5 of 42
(a) Number of relevant academic papers published yearly (b) Publications by research areas
Figure 1. Literature review analysis.
3. State of Art
3.1. Current Design Solution and Technologies
The concept of a dual-use approach for both solar photovoltaic power as well as ag-
ricultural production was theoretically conceived by Goetzberger and Zastrow at the
Fraunhofer Institute (Germany) in 1981 [1]. They proposed to elevate the structure (by
about 2 m) and the distance between rows (about 3 times the height of the modules) to
achieve uniform radiation on the ground while at the same time that allow the moving of
mechanized agricultural equipment. In 2004, Japanese engineer Akira Nagashima devel-
oped the first agrivoltaic system (here referred to as “solar sharing”) using a structure
similar to a garden pergola [2]. Nagashima designed diverse test fields with different
shadowing rates based on the concept of the light saturation point of each crop (plants
only employ a small percentage of incident sunlight (between 3% and 6% of total solar
radiation) to accomplish their maximum rate of photosynthesis) with the idea of sharing
the excess of solar radiation with PV systems to generate electricity. Graphical represen-
tations of both proposed solutions are presented in Figure 2.
Figure 2. First models of agrivoltaic systems: co-located agriculture and solar photovoltaic (APV). © Goetzberger and
Zastrow [1] (a), A. Nagashima [3] (b).
0
5
10
15
20
25
30
35
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
Publications
Year
29%
47%
24%
Open field
Innovative device
PV greenhouse
Figure 2.
First models of agrivoltaic systems: co-located agriculture and solar photovoltaic (APV).
©
Goetzberger and
Zastrow [1] (a), A. Nagashima [3] (b).
The first experimental pilot project, however, was installed in France, close to the
southern city of Montpellier (43
◦
65
0
N, 3
◦
87
0
E) in the spring of 2010. The prototype has
mono-crystalline PV modules mounted at a height of 4 m above the ground (Figure 3a,b).
Since the PV modules are opaque, the main issue is the effect of the shade created by PV on
the plant growth. In order to evaluate the effect of the shadow by the PV, the prototype was
split into different parts with two densities of solar modules: one called “full density”, with
optimal spacing between rows for electricity production and which transmitted on average
50% of the incident radiation to the crop, and the second called “half density”, obtained
by removing one PV strip out of two and which left on average 70% of incident radiation
available to the crop, so that the effect of the shadow by the PV can be compared to each
density, and to control plants under full sun conditions [
4
]. Additionally, to evaluate the
advantages of solar-tracking technology, which allows the adjustment of the radiation
level on crops, two independent single-axis tracking PV systems were added in 2014 [
5
]
(Figure 3c). The experimental farm led to the exploration of the potential of the open-field
agrivoltaic systems, giving rise to many scientific publications, from the effect of the rain
distribution (PV–water nexus) [
6
,
7
] to the impact on microclimatic condition together with
growth, morphology and yield in crops such as lettuce, cucumber and durum wheat [
8
–
10
].

Sustainability 2021,13, 6871 6 of 38
Sustainability 2021, 13, 6871 6 of 42
The first experimental pilot project, however, was installed in France, close to the
southern city of Montpellier (43°65′ N, 3°87′ E) in the spring of 2010. The prototype has
mono-crystalline PV modules mounted at a height of 4 m above the ground (Figures 3a,b).
Since the PV modules are opaque, the main issue is the effect of the shade created by PV
on the plant growth. In order to evaluate the effect of the shadow by the PV, the prototype
was split into different parts with two densities of solar modules: one called “full density”,
with optimal spacing between rows for electricity production and which transmitted on
average 50% of the incident radiation to the crop, and the second called “half density”,
obtained by removing one PV strip out of two and which left on average 70% of incident
radiation available to the crop, so that the effect of the shadow by the PV can be compared
to each density, and to control plants under full sun conditions [4]. Additionally, to eval-
uate the advantages of solar-tracking technology, which allows the adjustment of the ra-
diation level on crops, two independent single-axis tracking PV systems were added in
2014 [5] (Figure 3c). The experimental farm led to the exploration of the potential of the
open-field agrivoltaic systems, giving rise to many scientific publications, from the effect
of the rain distribution (PV–water nexus) [6,7] to the impact on microclimatic condition
together with growth, morphology and yield in crops such as lettuce, cucumber and du-
rum wheat [8–10].
(a) Structure 4 m above the ground (b) Mono-crystalline PV arrays (c) Single-axis sun tracking system
Figure 3. Experimental agrivoltaic system in Montpellier, France. © C. Dupraz.
In recent years, several research groups have implemented agrivoltaics demonstra-
tion projects around the world. In Germany, the Fraunhofer Institute for Solar Energy
Systems (Fraunhofer ISE) is at the forefront of APV research. A research pilot project was
installed in 2016 near Lake Constance in southern Germany under the project APV-
RESOLA [11]. This pilot research plant is used to examine the impacts of the technology
with regard to aspects such as energy production, economic feasibility, crop production,
social acceptance and technological design. It has a size of 0.3 ha and a capacity of 194
kWp. The solar modules are mounted on stilts with a vertical clearance of 5 m (Figures
4a,b). Moreover, in cooperation with their Chilean subsidiary Fraunhofer Center for Solar
Energy Technologies (Fraunhofer CSET), three further pilot plants have been realized
near Santiago de Chile to investigate the implementation of APV systems and its impact
on field crops in regions with arid areas and high solar radiation (Figure 4c).
Figure 3. Experimental agrivoltaic system in Montpellier, France. © C. Dupraz.
In recent years, several research groups have implemented agrivoltaics demonstration
projects around the world. In Germany, the Fraunhofer Institute for Solar Energy Systems
(Fraunhofer ISE) is at the forefront of APV research. A research pilot project was installed
in 2016 near Lake Constance in southern Germany under the project APV-RESOLA [
11
].
This pilot research plant is used to examine the impacts of the technology with regard to
aspects such as energy production, economic feasibility, crop production, social acceptance
and technological design. It has a size of 0.3 ha and a capacity of 194 kWp. The solar
modules are mounted on stilts with a vertical clearance of 5 m (Figure 4a,b). Moreover, in
cooperation with their Chilean subsidiary Fraunhofer Center for Solar Energy Technologies
(Fraunhofer CSET), three further pilot plants have been realized near Santiago de Chile to
investigate the implementation of APV systems and its impact on field crops in regions
with arid areas and high solar radiation (Figure 4c).
Sustainability 2021, 13, 6871 7 of 42
(a) Heggeslbach (Germany) (b) Heggeslbach (Germany) (c) Curacaví (Chile)
Figure 4. Experimental agrivoltaic systems installed by Fraunhofer ISE in Germany (a,b) and Chile (c). © Fraunhofer ISE.
The performance of the agrivoltaic systems in drylands is also under investigation
by the Barron-Gafford research group in the USA [12]. A small-scale research plant was
installed in Arizona at the Biosphere 2 Lab in August 2016. The research group focuses on
common agricultural species for drylands such as peppers, jalapeños and cherry tomatoes
[13]. The APV system is 3.3 m off the ground with a tilt of 32° and 1 m of spacing between
each row of PV modules.
Research in the field continues to progress at a furious pace. Aside from these pilot
projects, agrivoltaics have triggered much interest in the research community that ex-
plores the potential from different disciplinary perspectives and practical issues, such as
the solar power potential by land cover type (croplands, grasslands and wetlands) [14],
the water use efficiency in drylands [15] or groundwater stressed regions [16] (PV–water
nexus), the economic value of energy production coupled with shade tolerant crop pro-
duction [17], the implementation in peri-urban agriculture areas [18] or the viability over
shade-intolerant crops in specific geographical locations [19,20].
Although research in the field continues to progress, excitement around agrivoltaics
remains high enough that commercialization is well underway. Globally, the installed ca-
pacity of the APV continues to climb. It is estimated that 2200 systems have been installed
worldwide since 2014 (Japan is probably the country where the most agrivoltaic farms
were installed, with over 1992 APV farms which produced about 0.8% of total PV energy
in 2019), leading to a capacity of about 2.8 GWp as of January 2020 [21]. From the results
of the experimental farm in Montpellier, Sun’agri (FR) [22] was founded in cooperation
with Sun’R group. In 2018, the first agrivoltaic field was built in the east Pyrenean region
(France). This field has a capacity of 2.2 MWp installed on 4.5 ha of vineyards (Figure 5a).
Today, the company focuses on the development of large-scale demonstrator systems of
dynamic agrivoltaic technology in orchards, grapes and market gardening. In Italy, to-
gether with the University of Piacenza, REM Tec [23] patented an agrivoltaic solar track-
ing system named Agrovoltaico®. It was examined for maize crop production by Ama-
ducci et al. [24] while Agostini et al. assessed economic and environmental performance
[25]. The first two Agrovoltaico systems were installed in 2012 in Castelvetro Piacentino
(1.3 MWp, Figure 5b) and Monticelli d’Ongina (3.2 MWp) in the North of Italy covering an
area of 7 ha and 20 ha, respectively. In the Dutch town of Babberich, BayWa r.e. company
[26] has installed a 2.7 MWp raspberry agri-PV farm, being the largest agrivoltaic system
for fruit production in Europe (Figure 5c). Semi-transparent PV modules without frames
are mounted above the crop with a semi-enclosed single-row system, protecting from
weather phenomena, whilst providing better ventilation and reducing the use of pesti-
cides, thereby improving biodiversity in the fields.
Figure 4. Experimental agrivoltaic systems installed by Fraunhofer ISE in Germany (a,b) and Chile (c). © Fraunhofer ISE.
The performance of the agrivoltaic systems in drylands is also under investigation
by the Barron-Gafford research group in the USA [
12
]. A small-scale research plant was
installed in Arizona at the Biosphere 2 Lab in August 2016. The research group focuses
on common agricultural species for drylands such as peppers, jalapeños and cherry toma-
toes [
13
]. The APV system is 3.3 m off the ground with a tilt of 32
◦
and 1 m of spacing
between each row of PV modules.
Research in the field continues to progress at a furious pace. Aside from these pilot
projects, agrivoltaics have triggered much interest in the research community that explores
the potential from different disciplinary perspectives and practical issues, such as the solar
power potential by land cover type (croplands, grasslands and wetlands) [
14
], the water
use efficiency in drylands [
15
] or groundwater stressed regions [
16
] (PV–water nexus), the

Sustainability 2021,13, 6871 7 of 38
economic value of energy production coupled with shade tolerant crop production [
17
], the
implementation in peri-urban agriculture areas [
18
] or the viability over shade-intolerant
crops in specific geographical locations [19,20].
Although research in the field continues to progress, excitement around agrivoltaics
remains high enough that commercialization is well underway. Globally, the installed
capacity of the APV continues to climb. It is estimated that 2200 systems have been installed
worldwide since 2014 (Japan is probably the country where the most agrivoltaic farms
were installed, with over 1992 APV farms which produced about 0.8% of total PV energy
in 2019), leading to a capacity of about 2.8 GW
p
as of January 2020 [
21
]. From the results
of the experimental farm in Montpellier, Sun’agri (FR) [
22
] was founded in cooperation
with Sun’R group. In 2018, the first agrivoltaic field was built in the east Pyrenean region
(France). This field has a capacity of 2.2 MW
p
installed on 4.5 ha of vineyards (Figure 5a).
Today, the company focuses on the development of large-scale demonstrator systems of
dynamic agrivoltaic technology in orchards, grapes and market gardening. In Italy, together
with the University of Piacenza, REM Tec [
23
] patented an agrivoltaic solar tracking system
named Agrovoltaico
®
. It was examined for maize crop production by Amaducci et al. [
24
]
while Agostini et al. assessed economic and environmental performance [
25
]. The first two
Agrovoltaico systems were installed in 2012 in Castelvetro Piacentino (1.3 MW
p
, Figure
5b) and Monticelli d’Ongina (3.2 MW
p
) in the North of Italy covering an area of 7 ha and
20 ha, respectively. In the Dutch town of Babberich, BayWa r.e. company [
26
] has installed
a 2.7 MW
p
raspberry agri-PV farm, being the largest agrivoltaic system for fruit production
in Europe (Figure 5c). Semi-transparent PV modules without frames are mounted above
the crop with a semi-enclosed single-row system, protecting from weather phenomena,
whilst providing better ventilation and reducing the use of pesticides, thereby improving
biodiversity in the fields.
Sustainability 2021, 13, 6871 8 of 42
(a) Pionlec (France) (b) Castelvetro (Italy) (c) Babberich (Netherlands)
Figure 5. First demonstrator projects developed by the following companies: Sun’agri in France (a), REM Tec in Italy (b)
and BayWa r.e. in the Netherlands (c). © Sun’agri (a), REM Tec (b), BayWa r.e. (c).
However, concepts that combine farming and energy production on the same site are
not limited to stilted solar arrays (stripes) above crops. There are more design criteria with
PV modules mounted on the ground (less than 2 m of clearance height). Low height
mounting structures are then preferred because of their lower structure-related cost than
stilted agrivoltaics and the microclimate, which is generated underneath the solar mod-
ules so that crops grow in between the rows of PV arrays or underneath the modules de-
pending on the height of the plants and light requirements. Therefore, the area below
modules may be exploited with shade-tolerant species, especially in hot arid climates.
Some studies in this regard have already been carried out in India [27,28] and Malaysia
[29–32] for testing species such as java tea, aloe vera or spinach (Figure 6), achieving
higher crop yields for herbal plants while at the same time reducing the module temper-
ature by 0.85%, which may increase the annual energy production up to 2.8% [33], alt-
hough with a potential risk of pest due the high moisture [30].
(a) ICAR-Central Arid Zone Research
Institute, Jodhpur (India)
(b) Aravali foothills, north Gujarat
state (India)
(c) Hybrid Agrivoltaic System
Showcase, Putra University (Ma-
laysia)
Figure 6. Research pilot plants with low height PV mounting system. © P. Santra (a), B. Patel (b), N.F. Othman (c).
Some projects have also reached the market. Agrinergie® is the name of the systems
created by Akou Energy [34] group to combine energy generation from PV and crop pro-
duction, while considering landscape preservation issues. The first project which incor-
porates this concept was installed in the French tropical island of La Reunion. Two mod-
ules’ stripes are deliberately spaced to allow cultivation of lemongrass between them. The
ground has not been graded with the natural topography, as this helps to blend harmoni-
ously into the landscape (Figure 7a). More ground-based projects are being developed
Figure 5.
First demonstrator projects developed by the following companies: Sun’agri in France (
a
), REM Tec in Italy (
b
)
and BayWa r.e. in the Netherlands (c). © Sun’agri (a), REM Tec (b), BayWa r.e. (c).
However, concepts that combine farming and energy production on the same site
are not limited to stilted solar arrays (stripes) above crops. There are more design criteria
with PV modules mounted on the ground (less than 2 m of clearance height). Low height
mounting structures are then preferred because of their lower structure-related cost than
stilted agrivoltaics and the microclimate, which is generated underneath the solar modules
so that crops grow in between the rows of PV arrays or underneath the modules depending
on the height of the plants and light requirements. Therefore, the area below modules may
be exploited with shade-tolerant species, especially in hot arid climates. Some studies in
this regard have already been carried out in India [
27
,
28
] and Malaysia [
29
–
32
] for testing
species such as java tea, aloe vera or spinach (Figure 6), achieving higher crop yields for
herbal plants while at the same time reducing the module temperature by 0.85%, which

Sustainability 2021,13, 6871 8 of 38
may increase the annual energy production up to 2.8% [
33
], although with a potential risk
of pest due the high moisture [30].
Sustainability 2021, 13, 6871 8 of 42
(a) Pionlec (France) (b) Castelvetro (Italy) (c) Babberich (Netherlands)
Figure 5. First demonstrator projects developed by the following companies: Sun’agri in France (a), REM Tec in Italy (b)
and BayWa r.e. in the Netherlands (c). © Sun’agri (a), REM Tec (b), BayWa r.e. (c).
However, concepts that combine farming and energy production on the same site are
not limited to stilted solar arrays (stripes) above crops. There are more design criteria with
PV modules mounted on the ground (less than 2 m of clearance height). Low height
mounting structures are then preferred because of their lower structure-related cost than
stilted agrivoltaics and the microclimate, which is generated underneath the solar mod-
ules so that crops grow in between the rows of PV arrays or underneath the modules de-
pending on the height of the plants and light requirements. Therefore, the area below
modules may be exploited with shade-tolerant species, especially in hot arid climates.
Some studies in this regard have already been carried out in India [27,28] and Malaysia
[29–32] for testing species such as java tea, aloe vera or spinach (Figure 6), achieving
higher crop yields for herbal plants while at the same time reducing the module temper-
ature by 0.85%, which may increase the annual energy production up to 2.8% [33], alt-
hough with a potential risk of pest due the high moisture [30].
(a) ICAR-Central Arid Zone Research
Institute, Jodhpur (India)
(b) Aravali foothills, north Gujarat
state (India)
(c) Hybrid Agrivoltaic System
Showcase, Putra University (Ma-
laysia)
Figure 6. Research pilot plants with low height PV mounting system. © P. Santra (a), B. Patel (b), N.F. Othman (c).
Some projects have also reached the market. Agrinergie® is the name of the systems
created by Akou Energy [34] group to combine energy generation from PV and crop pro-
duction, while considering landscape preservation issues. The first project which incor-
porates this concept was installed in the French tropical island of La Reunion. Two mod-
ules’ stripes are deliberately spaced to allow cultivation of lemongrass between them. The
ground has not been graded with the natural topography, as this helps to blend harmoni-
ously into the landscape (Figure 7a). More ground-based projects are being developed
Figure 6. Research pilot plants with low height PV mounting system. © P. Santra (a), B. Patel (b), N.F. Othman (c).
Some projects have also reached the market. Agrinergie
®
is the name of the systems
created by Akou Energy [
34
] group to combine energy generation from PV and crop
production, while considering landscape preservation issues. The first project which
incorporates this concept was installed in the French tropical island of La Reunion. Two
modules’ stripes are deliberately spaced to allow cultivation of lemongrass between them.
The ground has not been graded with the natural topography, as this helps to blend
harmoniously into the landscape (Figure 7a). More ground-based projects are being
developed with innovative design concepts. Thus, vertical installations with bifacial PV
modules facing east and west and leaving the areas between the rows (about 10 m) for
agriculture is the idea behind the Next2Sun company (GE) [
35
]. Projects with an installed
capacity from 22 kW
p
(Figure 7b) to 4.1 MW
p
(Figure 7c) have already been developed in
Austria and Germany for the cultivation of potatoes and hay and silage, respectively.
Sustainability 2021, 13, 6871 9 of 42
with innovative design concepts. Thus, vertical installations with bifacial PV modules fac-
ing east and west and leaving the areas between the rows (about 10 m) for agriculture is
the idea behind the Next2Sun company (GE) [35]. Projects with an installed capacity from
22 kWp (Figure 7b) to 4.1 MWp (Figure 7c) have already been developed in Austria and
Germany for the cultivation of potatoes and hay and silage, respectively.
(a) Agrinergie system, Pierrefonds,
Reunion Island (France)
(b) Next2Sun vertical system, Gun-
tramsdorf (Austria)
(c) Next2Sun vertical system, Baden-
Wurttemberg (Germany)
Figure 7. Commercial plants with ground-based PV mounting system. © Akuo Energy (a), Next2Sun GmbH (b,c).
Depending on the location, weather conditions and land availability, crops need to
grow under climate control. In this case, the implementation of PV into agricultural set-
tings is through integrating PV modules into the greenhouse’s envelope, mainly the roof
[36–41]. However, conventional opaque PV modules produce shade, thereby significantly
affecting the microclimate inside the structure (air temperature, relative humidity, level
of light and CO2 concentration) and productivity [42–46]. To minimize this effect, one ap-
proach is to use completely opaque PV modules that cover part of the greenhouse roof or
PV modules with partial opaque sections that produce electricity (Figure 8a). In this way,
the percentage of the greenhouse area covered by opaque PV modules is reduced in such
a way that the light reaching the plants is sufficient for photosynthesis. Nevertheless, the
solar irradiance is still distributed non-uniformly and varies seasonally. Therefore, it is
necessary to find optimum arrangements of PV modules on the greenhouse roof in order
to define the optimal conditions for plant cultivation. Checkerboard arrangement, for in-
stance, has revealed better uniformity and consequently diminished the PV shading ef-
fects [47–52]. A recently published study—in which the yield estimations and the crop
planning of 14 horticultural and floricultural crops inside four PV greenhouse (PVG)
types, with coverage ratio ranging from 25% to 100%, is discussed—shows that all the
considered species (including high light demanding crops) can be cultivated inside PVGs
with 25% coverage ratio showing limited yield reductions (below 25%), but restrictions
on growth and yield occurred when the coverage ratio raised from 50% to 100% [53]. More
studies in literature, with diverse PV layouts in different roof geometries and covering
ratios, seem to confirm that the relative density ratio of opaque PV modules should not
exceed 50% (Table 3). This would provide a shading ratio that is compatible with green-
house cultivation.
Table 3. Studies where yield reductions or quality of plants of different species are not affected
significantly by the coverage of opaque PV modules integrated into the greenhouse’s roof.
% PV Roof Plant Reference
32% Berry [54]
26% Strawberry [55,56]
25% Wild rocket [57]
Figure 7. Commercial plants with ground-based PV mounting system. © Akuo Energy (a), Next2Sun GmbH (b,c).
Depending on the location, weather conditions and land availability, crops need to
grow under climate control. In this case, the implementation of PV into agricultural settings
is through integrating PV modules into the greenhouse’s envelope, mainly the roof [
36
–
41
].
However, conventional opaque PV modules produce shade, thereby significantly affecting
the microclimate inside the structure (air temperature, relative humidity, level of light
and CO
2
concentration) and productivity [
42
–
46
]. To minimize this effect, one approach

Sustainability 2021,13, 6871 9 of 38
is to use completely opaque PV modules that cover part of the greenhouse roof or PV
modules with partial opaque sections that produce electricity (Figure 8a). In this way, the
percentage of the greenhouse area covered by opaque PV modules is reduced in such a
way that the light reaching the plants is sufficient for photosynthesis. Nevertheless, the
solar irradiance is still distributed non-uniformly and varies seasonally. Therefore, it is
necessary to find optimum arrangements of PV modules on the greenhouse roof in order
to define the optimal conditions for plant cultivation. Checkerboard arrangement, for
instance, has revealed better uniformity and consequently diminished the PV shading
effects [
47
–
52
]. A recently published study—in which the yield estimations and the crop
planning of 14 horticultural and floricultural crops inside four PV greenhouse (PVG) types,
with coverage ratio ranging from 25% to 100%, is discussed—shows that all the considered
species (including high light demanding crops) can be cultivated inside PVGs with 25%
coverage ratio showing limited yield reductions (below 25%), but restrictions on growth
and yield occurred when the coverage ratio raised from 50% to 100% [
53
]. More studies in
literature, with diverse PV layouts in different roof geometries and covering ratios, seem
to confirm that the relative density ratio of opaque PV modules should not exceed 50%
(Table 3). This would provide a shading ratio that is compatible with greenhouse cultiva-
tion.
Table 3.
Studies where yield reductions or quality of plants of different species are not affected
significantly by the coverage of opaque PV modules integrated into the greenhouse’s roof.
% PV Roof Plant Reference
32% Berry [54]
26% Strawberry [55,56]
25% Wild rocket [57]
22% Pepper [58]
20% Pepper [59,60]
20% Lettuce [61–64]
20% Flowers (iberis, cyclaments and
petunias)[65]
20% Tomato [66]
10% Tomato [67–70]
To further control the light delivered to the crops according to their needs, shading
levels can be regulated dynamically. PV modules can rotate around fixed axes to adjust the
degree of shading inside the greenhouse (Figure 8b). Sun-tracking mechanisms are then
installed in the roof with PV rows used as slats of venetian blinds. The PV blind, oriented
parallel to the roof, partially blocks intense sunlight penetration into the greenhouse and
generates electricity, and perpendicular to the roof, the sunlight passes through the roof to
crops below the PV modules. Already, some researchers have investigated the feasibility of
using dynamic systems in greenhouses under different configurations:
•
Opaque PV modules mounted above the greenhouse roof at different PV densities
and layouts [71–73];
•
Opaque PV modules integrated into the roof coupling with high reflective mirrors in
order to allow for a better collection of reflective light (Figure 8b) [74–78];
•PV blinds installed underneath the greenhouse glass roof using semi-transparent PV
technology [79–81].
Researchers also propose additional strategies for the application of dynamic mecha-
nisms which allow control of the shading in an active way. Colantoni et al. [
65
] set up a rail
system inside a PV greenhouse prototype, where two rows of semi-transparent glass-glass
PV modules are installed. One row is fixed; the other one, mounted on top of the first, at
about 25 cm distance, moves to control the shading dynamically. The modules translate
over the fixed ones, and in combination with the others, enable a variation from 33% to 66%
of light transmission by overlapping the transparent part of PV modules located above

Sustainability 2021,13, 6871 10 of 38
with PV cells from the PV module placed below (and therefore configuration a dense or
porous layout). In all these cases, the shading level is regulated by a threshold parameter,
commonly the irradiance level, for the blind rotation or rail movement to adjust the ratio
for electricity production and for plant cultivation.
Progress in PV technology has also provided additional possibilities for application
in greenhouses. PV modules are not then conceived as partial shading systems where
the spacing or coverage must be optimized since the annual solar radiation available
inside a greenhouse may decrease with a ratio of 0.8% for each 1% of additional PV
cover ratio [
50
]. The sunlight quality (direct vs. diffuse; availability of PAR) management
inside the greenhouse is addressed by different innovative approaches: from using semi-
transparent films [
82
,
83
], the use of new materials or techniques to transmit to the plant
the diffuse component of the light [
84
] and devices based on spherical silicon micro-cells
(1.2 mm of diameter) where the overlapping of the PV cells over the sun barely eclipses the
plants [
85
,
86
] to sharing the solar spectrum through PV devices which generate electricity
outside the PAR regions [
87
–
90
]. (Only a small portion of the sunlight is used for efficient
plant growth. It is driven by two relative narrow wavelength regions: a red wavelength
band around 660 nm and a blue wavelength band around 450 nm. Green light contributes
less to photosynthesis due to the poor light absorption of chlorophyll in this region.)
Sustainability 2021, 13, 6871 11 of 42
been analyzed to optimize their performance in recent years [99–104]. In fact, commercial
production under this concept is already under way. Swiss startup Insolight [105] pa-
tented a system where optical lenses concentrate the direct sunlight onto tiny cells, which
cover only 0.5% of the module surface. The cells are able to track the sun through hori-
zontal movement of a few millimeters per day to keep the cells aligned with the light beam
component [106].
Along the development of CPV technology, wavelength-selective PV systems which
combine LSCs with PV have also attracted great interest from the scientific community.
Luminescent dyes are embedded into a transparent matrix, trapping and guiding some of
the incoming solar radiation at certain wavelengths and delivering to PV cells that are
integrated into the module (Figure 8c). Designs to optimize this technology for APV ap-
plications have been developed by Corrado et al. [107] to field-test studies to explore its
performance and reliability [108]. Additional research shows the potential of this technol-
ogy over species such basil [109], tomato [87] and microalgae [110].
(a) Fixed with different layouts (b) Dynamic (c) Innovative PV solution
Figure 8. Approaches to integrate PV into greenhouse’s envelope. © A. Yano [47] (a), A. Marucci [75] (b), M. E. Loik [87]
(c).
Customized PV modules to harness specific portions of the solar spectrum are also
possible by using thin film semi-transparent devices. Thompson et al. [111] recently pub-
lished a study where tinted semi-transparent solar modules (based on thin-film amor-
phous silicon technology) were tested for plant growth of basil and spinach. The results
highlight that even with a loss in the yield production, this solution could apport a finan-
cial gain of up to 2.5% for basil and 35% for spinach. Another opportunity is offered by
third-generation PV cells based on organic PV cells (OPV) or dye-sensitized solar cells
(DSSC). Emmott et al. [112] demonstrated the potential of OPV devices in greenhouses
modeling the impact on crop growth for a wide range of commercially available organic
semiconductor materials. Ravishankar et al. [113,114] reported that there are benefits of
integrating semi-transparent OPV to meet energy demand of greenhouses in warm and
moderate climates, being a potential candidate to achieve net-zero energy greenhouses.
Intensive research on OPV greenhouses currently focuses on developing new optimized
devices that minimize the impact on crop yield [115–119], to evaluate performance in real
operational conditions [120–124] and to study of the environmental impacts through the
life cycle assessment (LCA) methodology [125–127]. Variation in color and transparency
are characteristics that can be also achieved by DSSC technology being a potential candi-
date to be considered as a photo-selective covering for a greenhouse [128–134]. Despite
the specific features of third-generation PV devices (flexibility, light weight, diverse colors
and transparency degree, lower fabrication costs and environmental impact in compari-
son to silicon-based PV) and the new developments in the field, stability and efficiency
are still critical factors which must be improved to promote them as an alternative to PV
technologies consolidated at market levels.
Figure 8.
Approaches to integrate PV into greenhouse’s envelope.
©
A. Yano [
47
] (
a
), A. Marucci [
75
] (
b
), M. E. Loik [
87
] (
c
).
Recently, studies of combining concentrated photovoltaic (CPV) technology with
special bended glass modules (an optimized dichroitic polymer film which allows the
transmission of the blue light and red light for photosynthesis) has been reported with
an efficiency of 6.8% [
91
–
93
]. Previous studies in the same line show efficiencies of about
3.3% by only reflecting the near infrared radiation (NIR) fraction [
94
–
98
]. CPV technology
also allows the possibility to separate direct and diffuse light. Thus, systems that focus
direct radiation through Fresnel lenses, transmitting the diffuse sunlight to the crops, have
been analyzed to optimize their performance in recent years [
99
–
104
]. In fact, commercial
production under this concept is already under way. Swiss startup Insolight [
105
] patented
a system where optical lenses concentrate the direct sunlight onto tiny cells, which cover
only 0.5% of the module surface. The cells are able to track the sun through horizontal
movement of a few millimeters per day to keep the cells aligned with the light beam
component [106].
Along the development of CPV technology, wavelength-selective PV systems which
combine LSCs with PV have also attracted great interest from the scientific community.
Luminescent dyes are embedded into a transparent matrix, trapping and guiding some
of the incoming solar radiation at certain wavelengths and delivering to PV cells that
are integrated into the module (Figure 8c). Designs to optimize this technology for APV
applications have been developed by Corrado et al. [
107
] to field-test studies to explore

Sustainability 2021,13, 6871 11 of 38
its performance and reliability [
108
]. Additional research shows the potential of this
technology over species such basil [109], tomato [87] and microalgae [110].
Customized PV modules to harness specific portions of the solar spectrum are also
possible by using thin film semi-transparent devices. Thompson et al. [
111
] recently pub-
lished a study where tinted semi-transparent solar modules (based on thin-film amorphous
silicon technology) were tested for plant growth of basil and spinach. The results high-
light that even with a loss in the yield production, this solution could apport a financial
gain of up to 2.5% for basil and 35% for spinach. Another opportunity is offered by
third-generation PV cells based on organic PV cells (OPV) or dye-sensitized solar cells
(DSSC). Emmott et al. [
112
] demonstrated the potential of OPV devices in greenhouses
modeling the impact on crop growth for a wide range of commercially available organic
semiconductor materials. Ravishankar et al. [
113
,
114
] reported that there are benefits of
integrating semi-transparent OPV to meet energy demand of greenhouses in warm and
moderate climates, being a potential candidate to achieve net-zero energy greenhouses.
Intensive research on OPV greenhouses currently focuses on developing new optimized
devices that minimize the impact on crop yield [
115
–
119
], to evaluate performance in real
operational conditions [
120
–
124
] and to study of the environmental impacts through the
life cycle assessment (LCA) methodology [
125
–
127
]. Variation in color and transparency are
characteristics that can be also achieved by DSSC technology being a potential candidate
to be considered as a photo-selective covering for a greenhouse [
128
–
134
]. Despite the
specific features of third-generation PV devices (flexibility, light weight, diverse colors
and transparency degree, lower fabrication costs and environmental impact in comparison
to silicon-based PV) and the new developments in the field, stability and efficiency are
still critical factors which must be improved to promote them as an alternative to PV
technologies consolidated at market levels.
3.2. Further agri-PV Integrated Applications
This paper focuses mainly on crop farming applications where significant adjustments
to PV module infrastructure is needed, although other common approaches such as plant-
ing pollinators or livestock activities can also coexist along with PV, and they are beneficial
to the overall ecological performance of APV. Benefits of integrating grazing livestock has
been shown by Andrew, who analyzed the lamb growth and pasture production in Oregon
(USA). The study reveals that grazing under PV can increase land productivity up to 200%
as well as provide a more animal welfare and friendly environment [
135
]. In line with the
study of Andrew, Maia et al. determined livestock shade preference, showing that animals
spent more than 70% of their time under the shade from PV at irradiance values greater
than 800 W/m
2
[
136
]. Agrivoltaics can benefit local biodiversity, creating a habitat for
pollinators [
137
]. An ongoing study to quantify the potential is currently being carried out
by the US Renewable Energy Laboratory (NREL) through the InSPIRE project [
138
]. The
objective is studying pollinator-friendly solar in order to quantify the benefits and barriers
of certain design approaches.
3.3. Relevant Design Parameters and Performance Metrics
3.3.1. Height of the Modules from the Ground
The height of the systems from the ground (space in between the modules and the
ground surface) is an important design parameter since the use of higher structures, com-
monly associated with APV systems, can determine the homogeneity of the radiation
availability under the PV modules, improve the connectivity and allow the use of high
plants. The closer to the ground the modules are, the higher the heterogeneity of ra-
diation over the crops in the same land unit is (without considering the effects on the
surrounding areas).
However, there are also other implications when the modules are installed high
on the ground. For instance, taller configurations may result in several public concerns
or even rejection due to the negative impact (visibility is acknowledged as one of the

Sustainability 2021,13, 6871 12 of 38
complex objective factors that contribute to the visual impact of PV [
139
]) on areas
such as recreation and tourism [
140
–
142
]. The use of higher mounting structures not
only have influence on social acceptance but would also significantly affect the cost of
installation and the environmental impact. In the German context, the extra cost related to
elevating the PV modules (mounting, installation and site preparation costs) is assumed
to be more than double (increasing from 0.3 EUR/kW
p
to 0.7 EUR/kW
p
) compared to
ground-mounted PV [143].
The height of the system also can be used as a parameter of sustainability. Higher
emissions are related to larger size of the structure for elevating the modules. As the
LCA study of Serrano et al. [
144
] shows, an integrated PV parking lot (222 kW
p
) needs
72 t of steel, accounting for 82 t of CO
2
emissions, that, in comparison to the galvanized
steel structure of a conventional PV mounted system, generates eight times more CO
2
emissions. In the case of PVG, the gutter height also is an important design parameter since
it positively affects the cumulated global radiation inside the greenhouse; each additional 1
m of gutter height may increase by 3.8% the yearly global radiation on the PV greenhouse
compared to the conventional one [50].
Thus, high APV systems can be beneficial for the plants, as they allow for better solar
energy collection; nevertheless, literature also presents some concerns related to possible
detrimental effects on the ecological performance of the system.
3.3.2. Spatial Configuration of PV and Type of Crops
A module’s height and spacing may be adjusted to grow different types of crops
depending on plant light, humidity, temperature and space requirements. In this way,
zones for a successful growth can be identified. Thus, for ground-mounted PV installations
combined with low-height crops, three different areas are detected (Figure 9): zone 1 with a
low irradiance and high humidity level, zone 2 with regular light exposure and enough soil
moisture and zone 3, which shows the highest irradiation and lowest humidity [
145
]. In the
same way, APV for orchards or grapevines will need designs with tilt-mounted structures
and PV modules placed at higher heights to allow tree growth and farm machinery to
pass underneath.
Sustainability 2021, 13, 6871 13 of 42
low irradiance and high humidity level, zone 2 with regular light exposure and enough
soil moisture and zone 3, which shows the highest irradiation and lowest humidity [145].
In the same way, APV for orchards or grapevines will need designs with tilt-mounted
structures and PV modules placed at higher heights to allow tree growth and farm ma-
chinery to pass underneath.
Figure 9. Ground-mounted PV and crop zones (adapted from [145]).
Quality aspects (size, fruit coloration, sugar content, etc.) can be affected by the pas-
sive influence of the PV modules even though there are no significant yield losses. Ureña
et al. [68] shows that tomato cultivated under a PVG with 9.8% of PV covering area is
affected negatively in terms of fruit size and color although there is not a significant im-
pact on its yield and price. Bulgari et al. [146] also found a lower content of quality pa-
rameters for tomatoes with a configuration of 50% PV coverage besides lower yield by the
high PV percentage coverage. Cho et al. [147] detected lower weight and sugar content in
grapes cultivated in Korea than those of the control group, delaying the harvest time about
10 days, and the sugar-content level present almost the same level as that of the control
site. Conversely, some species including strawberry show good response in terms of qual-
ity (with higher chlorophyll content) and yield in comparison to unshaded treatment [55].
Despite the studies mentioned above, there is a little information on the effects on quality
parameters of the APV systems since they strongly depend on the season, crop type (with
its own adapted strategy in terms of morphology, yield or quality parameters) and micro-
climatic conditions given by the technical implementation of PV. Therefore, crop selection
method for agrivoltaic systems continues to be a key issue for the scientific community.
PV greenhouses are closed systems and should not be compared to open-field APV,
where the effect of shading has no significant effect on air temperature or relative humid-
ity. As covering ratio increases, the microclimate can play a negative role in the PV green-
house yield production or quality of the plant, reducing the amount of solar radiation and
thereby decreasing the air temperature and increasing the humidity. On the contrary, for
open-field crops and open-field PV, soil temperature can significantly decrease, affecting
the early phase of the plant growth [9].
Currently, the effectiveness of agrivoltaic systems, in terms of crop suitability, is an-
alyzed based on the priority of the biomass yield, which is directly related to the potential
benefit in terms of market value.
Zone 3 Zone 2 Zone 1
Irradiance
Humidity level
Min
Max
Min Max
Figure 9. Ground-mounted PV and crop zones (adapted from [145]).

Sustainability 2021,13, 6871 13 of 38
Quality aspects (size, fruit coloration, sugar content, etc.) can be affected by the
passive influence of the PV modules even though there are no significant yield losses.
Ureña et al. [
68
] shows that tomato cultivated under a PVG with 9.8% of PV covering area
is affected negatively in terms of fruit size and color although there is not a significant
impact on its yield and price. Bulgari et al. [
146
] also found a lower content of quality
parameters for tomatoes with a configuration of 50% PV coverage besides lower yield
by the high PV percentage coverage. Cho et al. [
147
] detected lower weight and sugar
content in grapes cultivated in Korea than those of the control group, delaying the harvest
time about 10 days, and the sugar-content level present almost the same level as that of
the control site. Conversely, some species including strawberry show good response in
terms of quality (with higher chlorophyll content) and yield in comparison to unshaded
treatment [
55
]. Despite the studies mentioned above, there is a little information on the
effects on quality parameters of the APV systems since they strongly depend on the
season, crop type (with its own adapted strategy in terms of morphology, yield or quality
parameters) and microclimatic conditions given by the technical implementation of PV.
Therefore, crop selection method for agrivoltaic systems continues to be a key issue for the
scientific community.
PV greenhouses are closed systems and should not be compared to open-field APV,
where the effect of shading has no significant effect on air temperature or relative humidity.
As covering ratio increases, the microclimate can play a negative role in the PV greenhouse
yield production or quality of the plant, reducing the amount of solar radiation and thereby
decreasing the air temperature and increasing the humidity. On the contrary, for open-field
crops and open-field PV, soil temperature can significantly decrease, affecting the early
phase of the plant growth [9].
Currently, the effectiveness of agrivoltaic systems, in terms of crop suitability, is
analyzed based on the priority of the biomass yield, which is directly related to the potential
benefit in terms of market value.
Dinesh and Pearce [
17
] show that if shade tolerant crops are used in APV, the crop
yield losses are minimized and computed that, for lettuce production in the US context, the
value of APV could reach over 30% when compared with conventional agriculture. In this
sense, the correlation between plant light requirements (given by the light saturation point
or, in other words, its degree of shade tolerance) and the percent of shade of the PV system
define the selection of the crop.
Japan, where the most agrivoltaic systems are installed to date, has identified a list of
the most important agrivoltaic crops suitable for the Japanese context through a repository
collected by Chiba University, with more than 120 species cultivated under agrivoltaic
farms along the country [
148
] providing a showcase of successful practices that have
contributed to the consolidation of these systems in the country. Likewise, the Japanese
Solar Sharing Network [
149
] provides a list of plants with advice on cultivation based on
the crop’s light saturation point.
Although there is a correlation between crop’s shade tolerance and biomass yield,
this seems to be only one of the multiple factors that define the effectiveness of the agri
PV solution. There are studies that show that the performance of shade-intolerant crops
with stilt-mounted PV structures present higher crop yields when compared to full sun
conditions. Sekiyama and Nagashima [
20
] applied a stilt-mounted solution with two
different configurations in terms of density to corn crop and found that the low-density
configuration produces larger values of biomass than control by 5.6%. The findings carried
out by the experiments on the Heggelbach farm in Germany show that seasonal temper-
ature variations influence the total yield production of wheat, potato, celery and clover
grass crops. Thus, in 2017, the production was reduced by
−
19% for wheat,
−
18% for
potato,
−
19% for celery and
−
5% for clover grass, contrary to the production in 2018,
characterized by a hot summer, changing to higher yields with +3%, +11% and +12% for
wheat, potato and celery, respectively, and scarcely affected clover grass with
−
8% under
the same system configuration [150].

Sustainability 2021,13, 6871 14 of 38
That is why further research is needed to define an accurate approach to classify the
crop suitability in this context. Some authors suggest a classification composed of three
categories: PLUS (+) for higher yields, ZERO (0) shows no influence and MINUS (
−
) is
a negative effect [
145
]. Obergfell [
151
] evaluated the most important crops in Germany
under this category. Based on field performance, the experiments carried out by the Barron-
Gafford research group [
13
] classify the impact from the agrivoltaic system mounted in
Arizona (USA) using this system with positive results on species such as basil (++), cabbage
(+), carrots (++), chard (+), chiltepin peppers (+), lemon grass (+), lettuce (++), marigolds
(+), sweet potatoes (++) and tomatoes (++); on the other hand, melon (0) and jalapeño (0)
production was nearly equal between PV and full sun treatments.
Nevertheless, there is no general consensus to date on a standardized system that
makes it possible to experimentally compare crop productivity under field conditions.
The above proposed classification could help to identify suitable crop groups through the
experience of different PV concepts in different operating conditions. However, in order
to achieve a common frame of reference, it will be necessary to establish thresholds for
crop yield reductions/increases to ensure that the dual use of the land unit enables the
generation of electricity while maintaining active and productive agriculture. In this sense,
farmers, who are the experts on their land, can define the tolerance of yield losses which
can serve as reference to set the levels for the classification. For instance, based on the
experience of the projects carried out in Germany, farmers reported they could tolerate crop
yield losses up to 20% [
152
], which coincides with the guidelines of the Japanese Ministry
of Agriculture, Forestry and Fishery (MAFF) for the implementation of PV systems on
existing crop-producing farmlands.
3.3.3. Performance Metrics
Since the APV system is composed of PV modules and farmland, the impact of land
use intensity on the energy performance of the system will determine an important part of
the feasibility of the whole system’s solution. In this sense, the land use energy intensity
can be quantified by metrics which express the land area use per unit of energy generation
(ha/kWh) and/or land area use per unit of capacity (ha/kW
p
), whereas the performance
can be expressed as unit of energy per unit of capacity over the course of a typical or actual
year (kWh/kWp/y), as commonly used for solar systems.
In order to assess the performance of the APV system, authors suggest using the
indicator land equivalent ratio (LER) that leads to comparing the conventional approach
(PV and farm set up separately) with the integrated solution on the same land area [
4
]. LER
measures whether the combined value of agricultural yield and solar energy is equal or
higher than it would be from the singular use of land. LER can be computed as:
LER =Yagri−APV
Yagri
+YAPV
YPV
(1)
where Y
agri
stands for agricultural yield (kg/ha for instance) in a single use of land for
farming and Y
agri-APV
refers to the yield under the agrivoltaic system for the same area. Y
PV
refers to the electricity production under a standard PV system assumption, and Y
APV
to the
agrivoltaic system. Thus, LER values above 1 indicate that the integrated approach is more
effective than separate crop production and PV for the same land area. (LER = 1.3 indicates
that 30% additional area would be needed to produce the same amount of electricity and
biomass on separate land areas.) However, caution must be taken in interpreting LER since
it does not differentiate the yield of biomass over the energy. Higher LER can be obtained
even if the crop yield represents only a small fraction of the system. For this reason, it
is also important to describe performance characteristics such as morphology, yield and
quality of the crop (as detailed in Section 3.3.2).
The impact of the PV design on agricultural production also can be quantified through
the water usage efficiency (WUE) as proposed by Adeh et al. [
153
] and Marrou et al. [
10
].

Sustainability 2021,13, 6871 15 of 38
WUE is then calculated as unit of biomass per unit of water used (commonly kg/m
3
)
against the biomass produced in a control zone without the influence of PV:
WUE =WUEPV −WUEcontrol
WUEcontrol
(2)
where WUEPV refers to the water efficiency under PV panels.
The technical feasibility is strongly influenced by the design parameters of the PV
system. Design criteria that consider a variation in azimuth and tilt angles of the modules
to meet the light requirements for an optimal crop growth affect other parameters such as
the land area occupation ratio (LAOR). (LAOR is the ratio between the area of the modules
and the area of land that they occupy, expressed in percentage. When modules are tilted,
there is a difference between the dimension of the height of the modules (that determines
the height of the stripe) and one of their orthogonal projections on the ground (what we see
in the pattern).) Nevertheless, considering that the average tilt angle of photovoltaic arrays
is about 30
◦
, the difference between these two values is neglectable (for modules 1.00 m
high, the projection on ground is 1.06 m); for higher tilt angles, this difference increases) and
thus, the normalized yearly energy generation and the land use intensity. Low tilt angles
and larger row distance mean higher LAOR values which minimize the shading effect
between rows, and enables enough radiation to allow the photosynthesis of the crop, but
to the detriment of electricity generation. Therefore, finding the trade-off between energy
and agricultural demands will require a careful analysis of the implications of selecting
the design criteria. A frame of reference can be given by specific metrics, best known as
key performance indicators (KPI), that are useful to analyze and compare existing facilities
creating an analytical basis which helps the decision-making process, and hence the future
development of these systems.
High LAOR values provide a high energy yield due to the amount of solar radiation
that reaches solar modules, whereas the crop yield will be low. LER is a combination of PV
and agriculture efficiency and comprises energy yield (unit of energy per unit of area on a
yearly basis, or by time parameters that farmers can set according to the growing season)
and agricultural yields, so the value also depends on local factors such as climate and crop
under test. LER should only be used as reference for similar climatic conditions, PV system
configuration and technology and crop. WUE is a useful parameter to assess the benefits of
the food–energy–water nexus in drylands.
4. A Trans-Disciplinary Cognitive Framework for the Design and Assessment
of Agrivoltaics
4.1. Innovative Three-Dimensional Patterns for Improved Ecological Performances
An agrivoltaic system is a complex system, being, at least, a spatial, an energy and an
agronomic system. Its design and assessment must adhere to requirements set depending
on the project’s needs in order to meet desired performance quality objectives. Different
dimensions of performance need to be taken into account. Moreover, the PV performance
and the agri performance are in opposition, as solutions optimized for PV are detrimental
to the sun caption of the plants (shading effects). This means that an optimization of the
PV performance in general implies some negative effects on the “other” performance, the
agri one.
It is crucial to understand what are the most influential parameters that can allow for
an optimal design of the overall integrated performance of agrivoltaic system, considering
the photovoltaic and the agri dimensions, and also some others, such as the effects on
water and microclimate (already analyzed in literature) and new ones related to additional
activities that may take place in the pore space of the APV pattern.
The analysis carried out so far demonstrates that the most influential design parame-
ters are the pattern of the system and the height of the modules from the ground.
The following figures (Figures 10 and 11) show the state of art with designs for
increasing the overall performance of the APV systems by varying the PV pattern (geometry

Sustainability 2021,13, 6871 16 of 38
and density) and the modules’ height (besides the technologies used for the PV systems
and modules).
Sustainability 2021, 13, 6871 17 of 42
(a) Montpellier (France), full density (b) Montpellier (France), half density
(c) Heggeslbach (Germany), Fraunhofer® (d) Babberich (Netherlands), BayWa r.e.®
(e) Castelvetro (Italy), Agrovoltaico® (f) Guntramsdorf (Austria), Next2Sun GmbH®
(g) Jodhpur (India), ICAR-Central Arid Zone Research Institute
Figure 10. Different pattern solutions currently implemented or under investigation in open-field type APV systems. In
the figures, the arrow is pointed north. The different solutions have an influence on irradiance and connectivity, as em-
phasized in Section 4.1, and different configurations create different pore zone types.
Figure 10.
Different pattern solutions currently implemented or under investigation in open-field type APV systems. In the
figures, the arrow is pointed north. The different solutions have an influence on irradiance and connectivity, as emphasized
in Section 4.1, and different configurations create different pore zone types.

Sustainability 2021,13, 6871 17 of 38
Sustainability 2021, 13, 6871 18 of 42
Figure 11. PV patterns in envelope integrated PV + protected crops systems (PV greenhouses). (a) Gable roof, dynamic
system. (b) Gable roof fixed system, different densities 15%, 25% and 50% (adapted from [154]). (c) tunnel greenhouse, up:
37% PV density [122–124], down: checkerboard arrangement [51,155]. (d) Gable roof, one pitch covered 100% [43], 25%
[47,48] checkerboard arrangement [47–52] and 20% [55,56]. (e) one pitch 100% and 32% covered [54] and semi-transparent
glass PV modules (by spacing PV cells) 50% of light transmittance [65,84]. (f) Asymmetrical greenhouse, dynamic ap-
proach [74–78].
If the implications of different design choices related to the variation in the pattern
(i.e., density) and in the height have been already emphasized, some new considerations
are possible if APVs are understood as solar sharing systems, being part of a landscape.
For instance, the orientation of the pattern stripes (the PV modules), which until now
mainly related to energy performance issues, can be varied so as to meet other objectives,
such as the creation of pathways in designed areas of the landscape for people to walk on.
The negative effects on the economical dimension related to the increased height of the
modules from the ground have been proposed in literature. Nevertheless, in view of pos-
sible additional solar sharing options related to the APV, the perspective may change, as
the structures of the APV can be seen as facilitating infrastructures (e.g., for the water
collection, or for ground stabilizing elements).
Moreover, higher APV systems allow for better connectivity, and this is a relevant
factor if additional functions related to animals and/or human activities are envisioned as
further options for APV. Such new functions (or business models) might also generate
beneficial effects for the economy (e.g., the use of APV areas as educational occasions for
the local community).
For this reason, a “three-dimensional spatial approach” seems to be suitable for sup-
porting design choices able to meet desired ecological quality objectives.
Figure 11.
PV patterns in envelope integrated PV + protected crops systems (PV greenhouses). (
a
)
Gable roof, dynamic system. (
b
) Gable roof fixed system, different densities 15%, 25% and 50%
(adapted from [
154
]). (
c
) tunnel greenhouse, up: 37% PV density [
122
–
124
], down: checkerboard
arrangement [
51
,
155
]. (
d
) Gable roof, one pitch covered 100% [
43
], 25% [
47
,
48
] checkerboard arrange-
ment [
47
–
52
] and 20% [
55
,
56
]. (
e
) one pitch 100% and 32% covered [
54
] and semi-transparent glass
PV modules (by spacing PV cells) 50% of light transmittance [
65
,
84
]. (
f
) Asymmetrical greenhouse,
dynamic approach [74–78].
If the implications of different design choices related to the variation in the pattern
(i.e., density) and in the height have been already emphasized, some new considerations
are possible if APVs are understood as solar sharing systems, being part of a landscape.
For instance, the orientation of the pattern stripes (the PV modules), which until now
mainly related to energy performance issues, can be varied so as to meet other objectives,
such as the creation of pathways in designed areas of the landscape for people to walk
on. The negative effects on the economical dimension related to the increased height of
the modules from the ground have been proposed in literature. Nevertheless, in view of
possible additional solar sharing options related to the APV, the perspective may change,
as the structures of the APV can be seen as facilitating infrastructures (e.g., for the water
collection, or for ground stabilizing elements).
Moreover, higher APV systems allow for better connectivity, and this is a relevant
factor if additional functions related to animals and/or human activities are envisioned
as further options for APV. Such new functions (or business models) might also generate
beneficial effects for the economy (e.g., the use of APV areas as educational occasions for
the local community).
For this reason, a “three-dimensional spatial approach” seems to be suitable for
supporting design choices able to meet desired ecological quality objectives.
4.2. A New Landscape Oriented Descriptive Model
In light of all the features found in the literature, different disciplinary perspectives
and related issues have to be considered in order to describe each system and identify di-
verse options and opportunities which correspond to performance quality objectives set by
different stakeholders (farmers, PV industry, researchers, policy makers, local authorities).
The study and development of APV systems requires, in fact, a truly trans-disciplinary ap-

Sustainability 2021,13, 6871 18 of 38
proach, as their design and implementation entail agrarian, engineering, technological and
energy issues, as well as landscape transformation and community acceptance ones. The
existing knowledge should be addressed in a way that allows for the inclusion of current
and future design issues and related ecological impacts. In this sense, some classifications
have been presented, such as those of Willockx et al. [
156
] and Trommsdorff et al. [
150
]
(this one mainly addresses first insights of how to design an open-field stilt-mounted type
agrivoltaic system in the German context), but broader and more varied research questions
must be addressed and discussed in a comprehensive methodological approach.
The background for the approach proposed here is the classification formulated
by Scognamiglio [
157
] for the photovoltaic landscape, which builds a methodology for
considering on ground PV as a part of the landscape, elaborating on fundamentals taken
from the landscape ecology discipline. The descriptive methodology is based on the
pattern-patch-matrix-corridor approach, as formalized by Forman [
158
], and then further
elaborated for the specific needs of PV.
Based on research studies and commercial developments two main morphologies (to
which multifaceted typologies are associated) were identified:
•On ground PV + open-field crops;
•Photovoltaic greenhouses (envelope integrated PV + protected crops).
Within the first category, two design approaches were detected in terms of installation
height: stilt-mounted PV (elevating the solar infrastructure range from 2 to 5 m) and
ground-mounted PV (Figure 12).
Sustainability 2021, 13, 6871 19 of 42
4.2. A New Landscape Oriented Descriptive Model
In light of all the features found in the literature, different disciplinary perspectives
and related issues have to be considered in order to describe each system and identify
diverse options and opportunities which correspond to performance quality objectives set
by different stakeholders (farmers, PV industry, researchers, policy makers, local author-
ities). The study and development of APV systems requires, in fact, a truly trans-discipli-
nary approach, as their design and implementation entail agrarian, engineering, techno-
logical and energy issues, as well as landscape transformation and community acceptance
ones. The existing knowledge should be addressed in a way that allows for the inclusion
of current and future design issues and related ecological impacts. In this sense, some
classifications have been presented, such as those of Willockx et al. [156] and Trommsdorff
et al. [150] (this one mainly addresses first insights of how to design an open-field stilt-
mounted type agrivoltaic system in the German context), but broader and more varied
research questions must be addressed and discussed in a comprehensive methodological
approach.
The background for the approach proposed here is the classification formulated by
Scognamiglio [157] for the photovoltaic landscape, which builds a methodology for con-
sidering on ground PV as a part of the landscape, elaborating on fundamentals taken from
the landscape ecology discipline. The descriptive methodology is based on the pattern-
patch-matrix-corridor approach, as formalized by Forman [158], and then further elabo-
rated for the specific needs of PV.
Based on research studies and commercial developments two main morphologies (to
which multifaceted typologies are associated) were identified:
• On ground PV + open-field crops;
• Photovoltaic greenhouses (envelope integrated PV + protected crops).
Within the first category, two design approaches were detected in terms of installa-
tion height: stilt-mounted PV (elevating the solar infrastructure range from 2 to 5 m) and
ground-mounted PV (Figure 12).
Figure 12. Agrivoltaic systems: typologies.
Thanks to the flexibility of the PV technology, integrated system configurations result
in solutions that meet a complex set of objectives, wider than those carried out by the
current PV design practices which only focus on prioritizing the energy generation at a
given land area. A variety of spatial arrangements by modifying PV arrays’ size, height
and spacing in different patterns can be described according to a set of spatial parameters.
In this context, energy and space features are strongly linked as a whole design approach
where the spatial configuration of PV patterns within the existing parcellation defines the
Figure 12. Agrivoltaic systems: typologies.
Thanks to the flexibility of the PV technology, integrated system configurations result
in solutions that meet a complex set of objectives, wider than those carried out by the
current PV design practices which only focus on prioritizing the energy generation at a
given land area. A variety of spatial arrangements by modifying PV arrays’ size, height
and spacing in different patterns can be described according to a set of spatial parameters.
In this context, energy and space features are strongly linked as a whole design approach
where the spatial configuration of PV patterns within the existing parcellation defines
the impact at landscape level. Therefore, the degree of porosity or density of the system
becomes a relevant attribute to describe the pore (we define the pore as the space left by PV
to host additional functions on the same land area) space (or the matrix) where the farming
activity will be hosted. Moreover, the change of scale to include greenhouse applications
can be covered by this approach through the analysis of the elements that comprise the
envelope of the greenhouse and its configuration.

Sustainability 2021,13, 6871 19 of 38
4.2.1. On Ground Photovoltaics + Open-Field Crops: The Agrivoltaic Pattern
Regarding the first family, the description assumes that the PV modules and the
associated structures are the elements of partition of the space, whereas the crops are
considered as a continuous in the considered area (matrix). The whole APV system is
described as the APV pattern, so as to align the description to that of the landscape, and,
i.e., the patch-corridor-matrix model [158].
The APV pattern is described as composed of photovoltaics and pore space (see
Figure 13).
The PV system is considered in its multifaceted features, and it is described accordingly
in terms of spatial features, energy features and engineering features. In this regard,
Oudes and Stremke [
159
] have recently published a comparative study that analyzes solar
landscapes by examining spatial properties, visibility, multifunctionality and temporality,
showing the imperative need to build analytical frameworks for analyzing PV systems in a
holistic manner, evaluating both individual properties and the system as a whole.
The spatial features are broken down into pattern and patch.
The pattern description gives an account of the spatial arrangement of the PV modules
through the size (qualitatively: with large patches, with small patches; quantitatively:
width, length, area); geometry (parallel stripes, checkboard, islands); type (continuous,
dispersed, random); and density (porous, dense, LAOR). (In assessing as “porous” or
“dense” a certain agrivoltaic pattern, here it is considered that about 40% of PV area/land
area is usually standard for agrivoltaic systems.)
The patch corresponds to the single unit of a stripe configuring a pattern; that is,
the PV module. It is therefore a repetition of PV modules, arranged along a line to
form a stripe configuration. A patch is described in terms of transparency (opaque or
semi-transparent/semi-translucent, and if semi-transparent or semi-translucent, the ratio
between the PV and the total area is given in %); size (length, width, area); orientation
(azimuth angle, tilt angle); color (qualitative assessment: name; quantitative assessment:
RAL code, hue, saturation, brightness); borders (thick, fine); and height from the ground.
(The assumption is considering the lowest side of the module for measuring the height
from the ground.)
The energy features are broken down into nominal power, number of modules, density
of power, land use energy intensity, normalized yearly energy generation and PV module
technology. For each of these categories, appropriate metrics are considered.
The engineering features are broken down into system typology (fixed, sun-tracking
one axis/two axis), modules supporting system (material, technology, weight) and founda-
tions (material, technology, weight).
The “pore space” (what is in between the PV modules, and in between the PV modules
and the ground) in the agrivoltaic pattern is described in terms of three-dimensional
pattern features, crop features (type, homogeneity, plant’s height and seasonality) and
energy features.
The three-dimensional pattern is an original descriptive expedient that the authors
propose for characterizing an APV system from the performance point of view, based on
the three-dimensional features of its pattern, referring to a unitary land area.
Sustainability 2021, 13, 6871 21 of 42
Figure 13. Cont.

Sustainability 2021,13, 6871 20 of 38
Sustainability 2021, 13, 6871 22 of 42
Figure 13. Cont.

Sustainability 2021,13, 6871 21 of 38
Sustainability 2021, 13, 6871 23 of 42
Figure 13. Cont.

Sustainability 2021,13, 6871 22 of 38
Sustainability 2021, 13, 6871 24 of 42
Figure 13. Comprehensive methodological approach to describe APV systems (on ground PV + open-field crops) from a
trans-disciplinary perspective (preliminary qualitative assessment).
Figure 13.
Comprehensive methodological approach to describe APV systems (on ground PV + open-field crops) from a
trans-disciplinary perspective (preliminary qualitative assessment).
The features of the three-dimensional pattern are average volume, area, zone type
(irradiation and connectivity) and crop density (crop area/total area %). The average
volume considers the pore space area (total land area minus the area corresponding to the

Sustainability 2021,13, 6871 23 of 38
projection of the PV modules on the ground) multiplied by the height of the modules from
the ground (considering the lowest line of the modules) (see Figure 14).
Sustainability 2021, 13, 6871 25 of 42
The “pore space” (what is in between the PV modules, and in between the PV mod-
ules and the ground) in the agrivoltaic pattern is described in terms of three-dimensional
pattern features, crop features (type, homogeneity, plant’s height and seasonality) and
energy features.
The three-dimensional pattern is an original descriptive expedient that the authors
propose for characterizing an APV system from the performance point of view, based on
the three-dimensional features of its pattern, referring to a unitary land area.
The features of the three-dimensional pattern are average volume, area, zone type
(irradiation and connectivity) and crop density (crop area/total area %). The average vol-
ume considers the pore space area (total land area minus the area corresponding to the
projection of the PV modules on the ground) multiplied by the height of the modules from
the ground (considering the lowest line of the modules) (see Figure 14).
Figure 14. The three-dimensional pattern of the APV systems.
The zone type qualitatively describes irradiation and connectivity that characterize
the pore area. Connectivity is defined as the degree to which the landscape facilitates or
impedes movement among resource patches. There are zones with high, medium and low
irradiation, and to these correspond high, medium and low connectivity.
Irradiation and connectivity basically depend on the degree of porosity of the PV
pattern and on the height of the PV modules from the ground: the more porous the pat-
tern, the higher the irradiance (and therefore the irradiation), whereas a high distance
from the ground implies generally a higher connectivity and a lower irradiance.
Figure 15 shows the influence of module height on irradiance. Given a certain PV
pattern and sun altitude, in fact, depending on the height of the modules from the ground,
it is possible to see that the dynamically shaded area decreases with the increase in the
height for the same area under the PV arrays. In Figure 15a, the color ranging from blue
to orange provides a qualitative assessment of the height effect on the irradiance, and
therefore on the irradiation. A quantitative assessment is more complex (a simple analysis
is shown in Figure 15b) and requires a simulation effort, as the degree of irradiation de-
pends on the dynamic shading on the ground.
Figure 14. The three-dimensional pattern of the APV systems.
The zone type qualitatively describes irradiation and connectivity that characterize
the pore area. Connectivity is defined as the degree to which the landscape facilitates or
impedes movement among resource patches. There are zones with high, medium and low
irradiation, and to these correspond high, medium and low connectivity.
Irradiation and connectivity basically depend on the degree of porosity of the PV
pattern and on the height of the PV modules from the ground: the more porous the pattern,
the higher the irradiance (and therefore the irradiation), whereas a high distance from the
ground implies generally a higher connectivity and a lower irradiance.
Figure 15 shows the influence of module height on irradiance. Given a certain PV
pattern and sun altitude, in fact, depending on the height of the modules from the ground, it
is possible to see that the dynamically shaded area decreases with the increase in the height
for the same area under the PV arrays. In Figure 15a, the color ranging from blue to orange
provides a qualitative assessment of the height effect on the irradiance, and therefore on
the irradiation. A quantitative assessment is more complex (a simple analysis is shown in
Figure 15b) and requires a simulation effort, as the degree of irradiation depends on the
dynamic shading on the ground.
Regarding the connectivity, Figure 16 shows that, given a certain PV pattern, the
connectivity increases along with the increase in the height of the modules from the ground.

Sustainability 2021,13, 6871 24 of 38
Sustainability 2021, 13, 6871 26 of 42
(a) Qualitative assessment. Shaded area decreases with the increase in the height for the
same area (crop area) under the PV system.
20-Jun 12:00 21-Dec 12:00
(b) Simulation for two cases: solar arrays elevated 0.5 m and 4 m above the ground. When
raising the structure, the shadow pattern falls on adjacent areas and does not affect the area
beneath the PV modules where the agricultural activity is hosted.
Figure 15. Irradiation vs. height of the photovoltaic modules on the ground.
Regarding the connectivity, Figure 16 shows that, given a certain PV pattern, the con-
nectivity increases along with the increase in the height of the modules from the ground.
Figure 16. Photovoltaic pattern and connectivity.
Figure 15. Irradiation vs. height of the photovoltaic modules on the ground.
Sustainability 2021, 13, 6871 26 of 42
(a) Qualitative assessment. Shaded area decreases with the increase in the height for the
same area (crop area) under the PV system.
20-Jun 12:00 21-Dec 12:00
(b) Simulation for two cases: solar arrays elevated 0.5 m and 4 m above the ground. When
raising the structure, the shadow pattern falls on adjacent areas and does not affect the area
beneath the PV modules where the agricultural activity is hosted.
Figure 15. Irradiation vs. height of the photovoltaic modules on the ground.
Regarding the connectivity, Figure 16 shows that, given a certain PV pattern, the con-
nectivity increases along with the increase in the height of the modules from the ground.
Figure 16. Photovoltaic pattern and connectivity.
Figure 16. Photovoltaic pattern and connectivity.
Figure 17 shows how, given a certain land area, a porous pattern increases both the
average irradiation on the crops and the connectivity.
Sustainability 2021, 13, 6871 27 of 42
Figure 17 shows how, given a certain land area, a porous pattern increases both the
average irradiation on the crops and the connectivity.
Figure 17. Porous pattern and connectivity.
Based on these considerations, zone types have been defined as high irradiation and
high/medium/low connectivity, medium irradiation and high/medium/low connectivity
and low irradiation and high/medium/low connectivity.
Then, the crop density is considered as the ratio between the crop area and the pore
area (%).
The crop features are plant’s height (uniform; nonuniform, and is uniform: height; if
nonuniform maximum, minimum and average height); seasonality (12, 6 or 3 months).
The energy features are irradiance (classified as high, average, low) and crop yield.
Being aware of the complexity in describing vegetable organisms, we propose this
preliminary classification as a starting point for creating a link between spatial features of
the pore area and crop selection based on low to high irradiance needs of the plants—and
also on additional animal or human activities that can take place in the pore area based
on connectivity degree.
4.2.2. Greenhouses (Envelope Integrated PV + Protected Crops)
The greenhouses (envelope integrated PV + protected crops) are described, keeping
into account the PV systems and the crop (see Figure 18). Technological systems for mi-
croclimate controlling and performance monitoring should be added for giving a complex
account of the greenhouse functioning, but this is out of the scope of this paper.
The envelope is broken down in morphology, material and dimensions.
Morphology refers to the cross section of the greenhouse, and it is therefore broken
down into one pitch, two pitches and curved. Each single pitch is described in terms of
area, height (minimum and maximum, respectively), orientation (azimuth angle, tilt an-
gle) and transparency (opaque, semi-transparent/semi-translucent).
For the envelope material, glass and others (plastic sheets, polycarbonate, etc.) are
considered.
The dimensions are side 1, side 2, area and volume.
Photovoltaics is broken down in PV system and PV modules. For each of them, spa-
tial features, energy features and typology are described.
For the PV system, spatial features are area (m2) and transparency (%). Energy fea-
tures are nominal power (kWp), normalized yearly energy production (kWh/kWp/y) and
density of power (kWp/m2). Typology is broken down into fixed and dynamic (lamellas
and sun-tracking).
For the PV modules, the spatial features are area (m2) and transparency (opaque,
semi-transparent/semi-translucent, transparency degree %). Energy features are nominal
power (kWp) and efficiency (W/m2). Typology is broken down into module technology
(monofacial, bifacial, concentrating; spectral selective) and layers and materials (front
Figure 17. Porous pattern and connectivity.

Sustainability 2021,13, 6871 25 of 38
Based on these considerations, zone types have been defined as high irradiation and
high/medium/low connectivity, medium irradiation and high/medium/low connectivity
and low irradiation and high/medium/low connectivity.
Then, the crop density is considered as the ratio between the crop area and the pore
area (%).
The crop features are plant’s height (uniform; nonuniform, and is uniform: height; if
nonuniform maximum, minimum and average height); seasonality (12, 6 or 3 months).
The energy features are irradiance (classified as high, average, low) and crop yield.
Being aware of the complexity in describing vegetable organisms, we propose this
preliminary classification as a starting point for creating a link between spatial features of
the pore area and crop selection based on low to high irradiance needs of the plants—and
also on additional animal or human activities that can take place in the pore area based on
connectivity degree.
4.2.2. Greenhouses (Envelope Integrated PV + Protected Crops)
The greenhouses (envelope integrated PV + protected crops) are described, keeping
into account the PV systems and the crop (see Figure 18). Technological systems for micro-
climate controlling and performance monitoring should be added for giving a complex
account of the greenhouse functioning, but this is out of the scope of this paper.
Sustainability 2021, 13, 6871 28 of 42
layer, PV layer, back layer, additional layer). The PV layer is further broken into standard
(thin film and crystalline technologies) and spectrum selective.
Figure 18. Cont.

Sustainability 2021,13, 6871 26 of 38
Sustainability 2021, 13, 6871 29 of 42
Figure 18. Cont.

Sustainability 2021,13, 6871 27 of 38
Sustainability 2021, 13, 6871 30 of 42
Figure 18. Cont.

Sustainability 2021,13, 6871 28 of 38
Sustainability 2021, 13, 6871 31 of 42
Figure 18. Comprehensive methodological approach to describe APV systems (envelope integrated PV + protected crops)
from a trans-disciplinary perspective (preliminary qualitative assessment).
4.3. Three-Dimensional Agrivoltaic Patterns and Related Metrics
Starting from the considerations thus far, some first preliminary metrics related to
the three-dimensional agrivoltaic pattern, useful for guiding and assessing the design of
sustainable APV systems, can be advanced (see Table 4). It is worth noting that there is
still room for exploring design possibilities of APV. This translates into a variety of possi-
bilities for the PV greenhouses, both in terms of envelope and technologies; whereas in
the case of the on-ground PV + open-field crops (agrivoltaic patterns), this translates into
the design and assessment of new patterns, which may be characterized by low or high
levels of “randomness”, both in terms of horizontal and vertical patterns of the PV mod-
ules (Figures 19 and 20), and leading, theoretically, to a kind of three-dimensional sparse
mosaic or to the PV modules fading out in space (with possible new ecological signifi-
cance).
Table 4. Three-dimensional APV pattern: definition and metrics.
Three-Dimensional Agrivoltaic Pattern: Main Metrics Involved
The three-dimensional agrivoltaic pattern (normalized “pore space”, be-
ing the pore space the space in between the PV modules and in between
the PV modules and the ground) corresponds to certain spatial configura-
tion of an APV system. It can be defined as a function of the volume of
the pore space given a unitary land area and a unitary modules height
(H).
For instance: 1 ha and 1 m.
The normalized pore space volume would then be: 100∗100∗1 = 10,000 m3
The density of the PV pattern influences the amount of the yearly irradia-
tion, while specific pattern configurations (geometrical arrangement of
the PV modules) influence the homogeneity of the irradiation on ground.
The height of the PV modules from the ground influences the degree of
connectivity (the degree to which the landscape facilitates or impedes
movement among resource patches) of the system.
Figure 18. Comprehensive methodological approach to describe APV systems (envelope integrated PV + protected crops)
from a trans-disciplinary perspective (preliminary qualitative assessment).
The envelope is broken down in morphology, material and dimensions.
Morphology refers to the cross section of the greenhouse, and it is therefore broken
down into one pitch, two pitches and curved. Each single pitch is described in terms of
area, height (minimum and maximum, respectively), orientation (azimuth angle, tilt angle)
and transparency (opaque, semi-transparent/semi-translucent).
For the envelope material, glass and others (plastic sheets, polycarbonate, etc.)
are considered.
The dimensions are side 1, side 2, area and volume.
Photovoltaics is broken down in PV system and PV modules. For each of them, spatial
features, energy features and typology are described.
For the PV system, spatial features are area (m
2
) and transparency (%). Energy
features are nominal power (kW
p
), normalized yearly energy production (kWh/kW
p
/y)
and density of power (kWp/m
2
). Typology is broken down into fixed and dynamic
(lamellas and sun-tracking).
For the PV modules, the spatial features are area (m
2
) and transparency (opaque,
semi-transparent/semi-translucent, transparency degree %). Energy features are nominal
power (kW
p
) and efficiency (W/m
2
). Typology is broken down into module technology
(monofacial, bifacial, concentrating; spectral selective) and layers and materials (front layer,
PV layer, back layer, additional layer). The PV layer is further broken into standard (thin
film and crystalline technologies) and spectrum selective.
4.3. Three-Dimensional Agrivoltaic Patterns and Related Metrics
Starting from the considerations thus far, some first preliminary metrics related to
the three-dimensional agrivoltaic pattern, useful for guiding and assessing the design of
sustainable APV systems, can be advanced (see Table 4). It is worth noting that there
is still room for exploring design possibilities of APV. This translates into a variety of
possibilities for the PV greenhouses, both in terms of envelope and technologies; whereas
in the case of the on-ground PV + open-field crops (agrivoltaic patterns), this translates into
the design and assessment of new patterns, which may be characterized by low or high
levels of “randomness”, both in terms of horizontal and vertical patterns of the PV modules
(Figures 19 and 20), and leading, theoretically, to a kind of three-dimensional sparse mosaic
or to the PV modules fading out in space (with possible new ecological significance).

Sustainability 2021,13, 6871 29 of 38
Table 4. Three-dimensional APV pattern: definition and metrics.
Three-Dimensional Agrivoltaic Pattern: Main Metrics Involved
The three-dimensional agrivoltaic pattern (normalized “pore space”, being the pore space the space in
between the PV modules and in between the PV modules and the ground) corresponds to certain spatial
configuration of an APV system. It can be defined as a function of the volume of the pore space given a
unitary land area and a unitary modules height (H).
For instance: 1 ha and 1 m.
The normalized pore space volume would then be: 100∗100∗1 = 10,000 m3
The density of the PV pattern influences the amount of the yearly irradiation, while specific pattern
configurations (geometrical arrangement of the PV modules) influence the homogeneity of the irradiation on
ground. The height of the PV modules from the ground influences the degree of connectivity (the degree to
which the landscape facilitates or impedes movement among resource patches) of the system.
Sustainability 2021, 13, 6871 31 of 42
Figure 18. Comprehensive methodological approach to describe APV systems (envelope integrated PV + protected crops)
from a trans-disciplinary perspective (preliminary qualitative assessment).
4.3. Three-Dimensional Agrivoltaic Patterns and Related Metrics
Starting from the considerations thus far, some first preliminary metrics related to
the three-dimensional agrivoltaic pattern, useful for guiding and assessing the design of
sustainable APV systems, can be advanced (see Table 4). It is worth noting that there is
still room for exploring design possibilities of APV. This translates into a variety of possi-
bilities for the PV greenhouses, both in terms of envelope and technologies; whereas in
the case of the on-ground PV + open-field crops (agrivoltaic patterns), this translates into
the design and assessment of new patterns, which may be characterized by low or high
levels of “randomness”, both in terms of horizontal and vertical patterns of the PV mod-
ules (Figures 19 and 20), and leading, theoretically, to a kind of three-dimensional sparse
mosaic or to the PV modules fading out in space (with possible new ecological signifi-
cance).
Table 4. Three-dimensional APV pattern: definition and metrics.
Three-Dimensional Agrivoltaic Pattern: Main Metrics Involved
The three-dimensional agrivoltaic pattern (normalized “pore space”, be-
ing the pore space the space in between the PV modules and in between
the PV modules and the ground) corresponds to certain spatial configura-
tion of an APV system. It can be defined as a function of the volume of
the pore space given a unitary land area and a unitary modules height
(H).
For instance: 1 ha and 1 m.
The normalized pore space volume would then be: 100∗100∗1 = 10,000 m3
The density of the PV pattern influences the amount of the yearly irradia-
tion, while specific pattern configurations (geometrical arrangement of
the PV modules) influence the homogeneity of the irradiation on ground.
The height of the PV modules from the ground influences the degree of
connectivity (the degree to which the landscape facilitates or impedes
movement among resource patches) of the system.
Three-Dimensional Pattern Spatial Attributes
PV PATTERN Density degree (PV area/ pore area) %
Geometry Continuous/Dispersed/Random
Number of crop zone types (depending on
irradiance) n
MODULES HEIGTH H m
PORE SPACE VOLUME (Pore area—PV area projection on the ground) ∗Hm3
(Site Depending) Solar Potential Parameters
YEARLY IRRADIATION kWh/m2/y
SOLAR POTENTIAL Yearly equivalent sun hours n
(Three-Dimensional Pattern) Depending Solar Potential And Connectivity Parameters
IRRADIANCE HOMOGENEITY DEGREE ON PV
Number ranging from 1 to 0 depending on whether
the orientation of PV is homogeneous or not. No
variation of tilt and azimuth is 1; no variation of
azimuth, variation of tilt or variation of azimuth, no
variation of tilt is 0.5; variation of azimuth and tilt is 0.
n (1; 0.5; 0)
IRRADIANCE HOMOGENEITY DEGREE ON
CROPS
Number ranging from 1 to 0 depending on whether
the geometrical pattern of PV is homogeneous (1),
dispersed (0.5) or random (0).
n (1; 0.5; 0)
CROP TYPE ZONES
The crop selection depends on irradiance. If the
irradiance is homogeneous, there is 1 zone type. If it
is not there, are more. For standard patterns (parallel
stripes with optimized distancing between the
stripes), there are 2 (one underneath the PV modules,
and the other in between the stripes of modules), but
a more porous pattern may allow for a third zone
with no shading.
n (1 or 2 or 3)
PV TYPE ZONES
Depending on how many different orientations of
the PV modules are, the number of PV type zones
can be determined.
n
CONNECTIVITY DEGREE (MATRIX
PERMEABILITY) Volume of the pore area/total area. %
Nominal Power Parameters
MODULES AREA m2
PV NOMINAL POWER Wp
CROP AREA m2
Solar Conversion Efficiency Parameters
MODULES EFFICIENCY %
ENERGY DENSITY PARAMETERS
PV DENSITY OF POWER W/m2
LAND USE ENERGY INTENSITY kWh/m2/y
PLANTS DENSITY OF MASS Kg/m2
Producibility Parameters (should be calculated based on yearly equivalent Sun hours)
NORMALIZED PV PRODUCIBILITY kWh/kWp/y
PV YEARLY YIELD MWh/y
CROPS YEARLY YIELD q/y

Sustainability 2021,13, 6871 30 of 38
Sustainability 2021, 13, 6871 33 of 42
Solar Conversion Efficiency Parameters
MODULES EFFICIENCY %
ENERGY DENSITY PARAMETERS
PV DENSITY OF POWER W/m2
LAND USE ENERGY INTENSITY kWh/m2/y
PLANTS DENSITY OF MASS Kg/m2
Producibility Parameters (should be calculated based on yearly equivalent Sun hours)
NORMALIZED PV PRODUCIBIL-
ITY kWh/kWp/y
PV YEARLY YIELD MWh/y
CROPS YEARLY YIELD q/y
Figure 19. The design and assessment of agrivoltaics open new perspectives if the system is ap-
proached as a three-dimensional pattern characterized by a certain degree of randomness, both in
the horizontal and vertical arrangement of the modules. The limit point is that PV modules fade out
in space, with possible new related ecological performances.
Figure 20. Suggestion for a three-dimensional photovoltaic random pattern. Solar Drifts, designed by Balmori Associates.
University of Buffalo, Buffalo Solar Park, NY, USA. Competition Finalist, 2010 [160].
Figure 19.
The design and assessment of agrivoltaics open new perspectives if the system is ap-
proached as a three-dimensional pattern characterized by a certain degree of randomness, both in the
horizontal and vertical arrangement of the modules. The limit point is that PV modules fade out in
space, with possible new related ecological performances.
Sustainability 2021, 13, 6871 33 of 42
Solar Conversion Efficiency Parameters
MODULES EFFICIENCY %
ENERGY DENSITY PARAMETERS
PV DENSITY OF POWER W/m2
LAND USE ENERGY INTENSITY kWh/m2/y
PLANTS DENSITY OF MASS Kg/m2
Producibility Parameters (should be calculated based on yearly equivalent Sun hours)
NORMALIZED PV PRODUCIBIL-
ITY kWh/kWp/y
PV YEARLY YIELD MWh/y
CROPS YEARLY YIELD q/y
Figure 19. The design and assessment of agrivoltaics open new perspectives if the system is ap-
proached as a three-dimensional pattern characterized by a certain degree of randomness, both in
the horizontal and vertical arrangement of the modules. The limit point is that PV modules fade out
in space, with possible new related ecological performances.
Figure 20. Suggestion for a three-dimensional photovoltaic random pattern. Solar Drifts, designed by Balmori Associates.
University of Buffalo, Buffalo Solar Park, NY, USA. Competition Finalist, 2010 [160].
Figure 20.
Suggestion for a three-dimensional photovoltaic random pattern. Solar Drifts, designed by Balmori Associates.
University of Buffalo, Buffalo Solar Park, NY, USA. Competition Finalist, 2010 [160].
5. Conclusions
The energy and engineering design optimization, the development of new technolo-
gies and the correct selection of plant species adapted to the PV system are the areas
where the current research is actively focusing in APV systems. Along with the continuous
research progress, the success of several international experiences through pilot projects
which implement new design solutions and use different PV technologies (showing the
technical potential in real working conditions) has triggered APV, and it has been met with
great acceptance from the industry and interest from governments. It is in fact a significant
potential contribution to meet climate challenges touching on food, energy, agriculture
and rural policies [
161
,
162
]. Moreover, it is understood—i.e., by energy developers—as
a possible driver for the implementation of large-scale PV installations and building-
integrated agriculture [
163
], which without the APV function, would not be successful in
the authorization process due to land use concerns.
A sharp increase is expected in terms of number of installations and capacity in the
near future. Along this trend, new concerns regarding landscape and urban transforma-
tion issues are emerging as the implementation of APV might be mainly focused on the
efficiency of the PV system (more profitable than agriculture), with insufficient attention
on the correct synergy between energy and food production.
The landscape, as intended by the European Landscape Convention [
164
], is the correct
dimension where issues can be faced in view of an improved ecological performance of the
systems. The mere technical perspective must be overcome in favor of a more inclusive,
sustainable one that considers new approaches for conceiving APV patterns. These may
include, for instance, new community-oriented functions (e.g., educational or recreational)
that can empower the use of APV as solar-sharing solutions (energy, agri, community).
The proposed framework, which describes the APV systems as three-dimensional
landscape patterns, seeks to characterize them from a new inclusive design vision enabling

Sustainability 2021,13, 6871 31 of 38
understanding of the tight connection between energy and space and making some room
for other new considerations (i.e., landscape related). A set of parameters classified by
category to define an APV system as a part of the landscape (pattern, patch, pore) including
different disciplinary contents (photovoltaic technology, agronomy, engineering) has been
formalized, guiding and assessing the design of agrivoltaic systems in view of desired
quality objectives. Under this perspective, the need for new APV-related research emerges.
The study of ecosystem service trade-offs in the spatial planning and design for energy
transition, to identify potential synergies and minimize trade-offs between renewable
energy and other ecosystem services, has been already acknowledged as a key issue for
avoiding conflicts between global and local perspectives [165].
Further specific actions towards the formalization of an appropriate cognitive frame-
work for APV are a multidimensional performance matrix including heterogeneous perfor-
mance indicators for assessing the overall ecosystem performance of the systems and the
experimentation with new innovative patterns able to include community functions.
The development of new innovative systems (PV system technology) and components
(photovoltaic devices technology) can enhance the energy performance of selected design
options for APV greenhouse typology.
None of these perspectives can overlook a truly inter-disciplinary and even trans-
disciplinary approach.
Author Contributions:
Conceptualization by A.S. and C.T.; State of Art by C.T.; relevant design
parameters and performance metrics by A.S. and C.T.; trans-disciplinary cognitive framework for the
design and assessment of agrivoltaics by A.S.; conclusions by A.S. and C.T. All authors have written
and reviewed the paper. All authors have read and agreed to the published version
of the manuscript
.
Funding:
This work was supported by the Italian Ministry of Economic Development in the frame-
work of the Operating Agreement with ENEA for Research on the Electric System.
Institutional Review Board Statement: Not applicable.
Informed Consent Statement: Not applicable.
Acknowledgments:
Carlos Toledo is grateful for postdoctoral fellowship 21227/PD/19. Fundación
Séneca. Región de Murcia (Spain).
Conflicts of Interest: The authors declare no conflict of interest.
Nomenclature
APV Agrivoltaics
BIPV Building integrated photovoltaics
CPV Concentrated photovoltaics
DSSC Dye-sensitized solar cell
KPI Key performance indicator
LAOR Land area occupation ratio
LCA Life cycle assessment
LER Land equivalent ratio
LSC Luminescent solar concentrator
NIR Near infrared radiation
OPV Organic photovoltaics
PAR Photosynthetically active radiation
PCE Power conversion efficiency
PV Photovoltaics
PVG Photovoltaics greenhouses
WUE Water usage efficiency
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