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While photovoltaic (PV) renewable energy production has surged, concerns remain about whether or not PV power plants induce a “heat island” (PVHI) effect, much like the increase in ambient temperatures relative to wildlands generates an Urban Heat Island effect in cities. Transitions to PV plants alter the way that incoming energy is reflected back to the atmosphere or absorbed, stored, and reradiated because PV plants change the albedo, vegetation, and structure of the terrain. Prior work on the PVHI has been mostly theoretical or based upon simulated models. Furthermore, past empirical work has been limited in scope to a single biome. Because there are still large uncertainties surrounding the potential for a PHVI effect, we examined the PVHI empirically with experiments that spanned three biomes. We found temperatures over a PV plant were regularly 3–4 °C warmer than wildlands at night, which is in direct contrast to other studies based on models that suggested that PV systems should decrease ambient temperatures. Deducing the underlying cause and scale of the PVHI effect and identifying mitigation strategies are key in supporting decision-making regarding PV development, particularly in semiarid landscapes, which are among the most likely for large-scale PV installations.
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Scientific RepoRts | 6:35070 | DOI: 10.1038/srep35070
The Photovoltaic Heat Island
Eect: Larger solar power plants
increase local temperatures
Greg A. Barron-Gaord1,2, Rebecca L. Minor1,2, Nathan A. Allen3, Alex D. Cronin4,
Adria E. Brooks5 & Mitchell A. Pavao-Zuckerman6
While photovoltaic (PV) renewable energy production has surged, concerns remain about whether
or not PV power plants induce a “heat island” (PVHI) eect, much like the increase in ambient
temperatures relative to wildlands generates an Urban Heat Island eect in cities. Transitions to PV
plants alter the way that incoming energy is reected back to the atmosphere or absorbed, stored, and
reradiated because PV plants change the albedo, vegetation, and structure of the terrain. Prior work
on the PVHI has been mostly theoretical or based upon simulated models. Furthermore, past empirical
work has been limited in scope to a single biome. Because there are still large uncertainties surrounding
the potential for a PHVI eect, we examined the PVHI empirically with experiments that spanned
three biomes. We found temperatures over a PV plant were regularly 3–4 °C warmer than wildlands
at night, which is in direct contrast to other studies based on models that suggested that PV systems
should decrease ambient temperatures. Deducing the underlying cause and scale of the PVHI eect and
identifying mitigation strategies are key in supporting decision-making regarding PV development,
particularly in semiarid landscapes, which are among the most likely for large-scale PV installations.
Electricity production from large-scale photovoltaic (PV) installations has increased exponentially in recent dec-
ades1–3. is proliferation in renewable energy portfolios and PV powerplants demonstrate an increase in the
acceptance and cost-eectiveness of this technology4,5. Corresponding with this upsurge in installation has been
an increase in the assessment of the impacts of utility-scale PV4,6–8, including those on the ecacy of PV to oset
energy needs9,10. A growing concern that remains understudied is whether or not PV installations cause a “heat
island” (PVHI) eect that warms surrounding areas, thereby potentially inuencing wildlife habitat, ecosystem
function in wildlands, and human health and even home values in residential areas11. As with the Urban Heat
Island (UHI) eect, large PV power plants induce a landscape change that reduces albedo so that the modied
landscape is darker and, therefore, less reective. Lowering the terrestrial albedo from ~20% in natural deserts12
to ~5% over PV panels13 alters the energy balance of absorption, storage, and release of short- and longwave
radiation14,15. However, several dierences between the UHI and potential PVHI eects confound a simple com-
parison and produce competing hypotheses about whether or not large-scale PV installations will create a heat
island eect. ese include: (i) PV installations shade a portion of the ground and therefore could reduce heat
absorption in surface soils16, (ii) PV panels are thin and have little heat capacity per unit area but PV modules
emit thermal radiation both up and down, and this is particularly signicant during the day when PV modules
are oen 20 °C warmer than ambient temperatures, (iii) vegetation is usually removed from PV power plants,
reducing the amount of cooling due to transpiration14, (iv) electric power removes energy from PV power plants,
and (v) PV panels reect and absorb upwelling longwave radiation, and thus can prevent the soil from cooling as
much as it might under a dark sky at night.
Public concerns over a PVHI eect have, in some cases, led to resistance to large-scale solar development. By
some estimates, nearly half of recently proposed energy projects have been delayed or abandoned due to local
opposition11. Yet, there is a remarkable lack of data as to whether or not the PVHI eect is real or simply an issue
1School of Geography & Development, University of Arizona, Tucson, AZ, USA. 2Oce of Research & Development;
College of Science, Biosphere 2, University of Arizona, Tucson, AZ, USA. 3Nevada Center of Excellence, Desert
Research Institute, Las Vegas, NV, USA. 4Department of Physics, University of Arizona, Tucson, AZ, USA. 5Department
of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, WI, USA. 6Department of
Environmental Science & Technology, University of Maryland, College Park, MD, USA. Correspondence and requests
for materials should be addressed to G.A.B.-G. (email:
Received: 26 May 2016
Accepted: 23 September 2016
Published: 13 October 2016
Scientific RepoRts | 6:35070 | DOI: 10.1038/srep35070
associated with perceptions of environmental change caused by the installations that lead to “not in my back-
yard” (NIMBY) thinking. Some models have suggested that PV systems can actually cause a cooling eect on the
local environment, depending on the eciency and placement of the PV panels17,18. But these studies are limited
in their applicability when evaluating large-scale PV installations because they consider changes in albedo and
energy exchange within an urban environment (rather than a natural ecosystem) or in European locations that
are not representative of semiarid energy dynamics where large-scale PV installations are concentrated10,19. Most
previous research, then, is based on untested theory and numerical modeling. erefore, the potential for a PHVI
eect must be examined with empirical data obtained through rigorous experimental terms.
The significance of a PVHI effect depends on energy balance. Incoming solar energy typically is either
reected back to the atmosphere or absorbed, stored, and later re-radiated in the form of latent or sensible heat
(Fig.1)20,21. Within natural ecosystems, vegetation reduces heat gain and storage in soils by creating surface shad-
ing, though the degree of shading varies among plant types22. Energy absorbed by vegetation and surface soils can
be released as latent heat in the transition of liquid water to water vapor to the atmosphere through evapotranspi-
ration – the combined water loss from soils (evaporation) and vegetation (transpiration). is heat-dissipating
latent energy exchange is dramatically reduced in a typical PV installation (Fig.1 transition from A-to-B), poten-
tially leading to greater heat absorption by soils in PV installations. is increased absorption, in turn, could
increase soil temperatures and lead to greater sensible heat eux from the soil in the form of radiation and con-
vection. Additionally, PV panel surfaces absorb more solar insolation due to a decreased albedo13,23,24. PV panels
will re-radiate most of this energy as longwave sensible heat and convert a lesser amount (~20%) of this energy
into usable electricity. PV panels also allow some light energy to pass, which, again, in unvegetated soils will
lead to greater heat absorption. is increased absorption could lead to greater sensible heat eux from the soil
that may be trapped under the PV panels. A PVHI eect would be the result of a detectable increase in sensible
heat ux (atmospheric warming) resulting from an alteration in the balance of incoming and outgoing energy
uxes due to landscape transformation. Developing a full thermal model is challenging17,18,25, and there are large
uncertainties surrounding multiple terms including variations in albedo, cloud cover, seasonality in advection,
and panel eciency, which itself is dynamic and impacted by the local environment. ese uncertainties are
compounded by the lack of empirical data.
We addressed the paucity of direct quantication of a PVHI eect by simultaneously monitoring three sites
that represent a natural desert ecosystem, the traditional built environment (parking lot surrounded by com-
mercial buildings), and a PV power plant. We dene a PVHI eect as the dierence in ambient air temperature
between the PV power plant and the desert landscape. Similarly, UHI is dened as the dierence in temperature
between the built environment and the desert. We reduced confounding eects of variability in local incoming
energy, temperature, and precipitation by utilizing sites contained within a 1 km area.
At each site, we monitored air temperature continuously for over one year using aspirated temperature probes
2.5 m above the soil surface. Average annual temperature was 22.7 + 0.5 °C in the PV installation, while the nearby
desert ecosystem was only 20.3 + 0.5 °C, indicating a PVHI eect. Temperature dierences between areas varied
signicantly depending on time of day and month of the year (Fig.2), but the PV installation was always greater
than or equal in temperature to other sites. As is the case with the UHI eect in dryland regions, the PVHI eect
delayed the cooling of ambient temperatures in the evening, yielding the most signicant dierence in overnight
temperatures across all seasons. Annual average midnight temperatures were 19.3 + 0.6 °C in the PV installation,
while the nearby desert ecosystem was only 15.8 + 0.6 °C. is PVHI eect was more signicant in terms of actual
degrees of warming (+ 3.5 °C) in warm months (Spring and Summer; Fig.3, right).
Figure 1. Illustration of midday energy exchange. Assuming equal rates of incoming energy from the sun, a
transition from (A) a vegetated ecosystem to (B) a photovoltaic (PV) power plant installation will signicantly
alter the energy ux dynamics of the area. Within natural ecosystems, vegetation reduces heat capture and
storage in soils (orange arrows), and inltrated water and vegetation release heat-dissipating latent energy uxes
in the transition of water-to-water vapor to the atmosphere through evapotranspiration (blue arrows). ese
latent heat uxes are dramatically reduced in typical PV installations, leading to greater sensible heat uxes (red
arrows). Energy re-radiation from PV panels (brown arrow) and energy transferred to electricity (purple arrow)
are also shown.
Scientific RepoRts | 6:35070 | DOI: 10.1038/srep35070
In both PVHI and UHI scenarios, the greater amount of exposed ground surfaces compared to natural sys-
tems absorbs a larger proportion of high-energy, shortwave solar radiation during the day. Combined with min-
imal rates of heat-dissipating transpiration from vegetation, a proportionally higher amount of stored energy is
reradiated as longwave radiation during the night in the form of sensible heat (Fig.1)15. Because PV installations
introduce shading with a material that, itself, should not store much incoming radiation, one might hypothesize
that the eect of a PVHI eect would be lesser than that of a UHI. Here, we found that the dierence in evening
ambient air temperature was consistently greater between the PV installation and the desert site than between the
parking lot (UHI) and the desert site (Fig.3). e PVHI eect caused ambient temperature to regularly approach
or be in excess of 4 °C warmer than the natural desert in the evenings, essentially doubling the temperature
increase due to UHI measured here. is more signicant warming under the PVHI than the UHI may be due
to heat trapping of re-radiated sensible heat ux under PV arrays at night. Daytime dierences from the natural
ecosystem were similar between the PV installation and urban parking lot areas, with the exception of the Spring
and Summer months, when the PVHI eect was signicantly greater than UHI in the day. During these warm
seasons, average midnight temperatures were 25.5 + 0.5 °C in the PV installation and 23.2 + 0.5 °C in the parking
lot, while the nearby desert ecosystem was only 21.4 + 0.5 °C.
e results presented here demonstrate that the PVHI eect is real and can signicantly increase temperatures
over PV power plant installations relative to nearby wildlands. More detailed measurements of the underlying
causes of the PVHI eect, potential mitigation strategies, and the relative inuence of PVHI in the context of the
intrinsic carbon osets from the use of this renewable energy are needed. us, we raise several new questions
and highlight critical unknowns requiring future research.
What is the physical basis of land transformations that might cause a PVHI?
We hypothesize that the PVHI eect results from the eective transition in how energy moves in and out of a PV
installation versus a natural ecosystem. However, measuring the individual components of an energy ux model
remains a necessary task. ese measurements are dicult and expensive but, nevertheless, are indispensable
in identifying the relative inuence of multiple potential drivers of the PVHI eect found here. Environmental
Figure 2. Average monthly ambient temperatures throughout a 24-hour period provide evidence of a
photovoltaic heat island (PVHI) eect.
Scientific RepoRts | 6:35070 | DOI: 10.1038/srep35070
conditions that determine patterns of ecosystem carbon, energy, and water dynamics are driven by the means
through which incoming energy is reected or absorbed. Because we lack fundamental knowledge of the changes
in surface energy uxes and microclimates of ecosystems undergoing this land use change, we have little ability to
predict the implications in terms of carbon or water cycling4,8.
What are the physical implications of a PVHI, and how do they vary by region?
e size of an UHI is determined by properties of the city, including total population26–28, spatial extent, and the
geographic location of that city29–31. We should, similarly, consider the spatial scale and geographic position of
a PV installation when considering the presence and importance of the PVHI eect. Remote sensing could be
coupled with ground-based measurements to determine the lateral and vertical extent of the PVHI eect. We
could then determine if the size of the PVHI eect scales with some measure of the power plant (for example,
panel density or spatial footprint) and whether or not a PVHI eect reaches surrounding areas like wildlands and
neighborhoods. Given that dierent regions around the globe each have distinct background levels of vegetative
ground cover and thermodynamic patterns of latent and sensible heat exchange, it is possible that a transition
from a natural wildland to a typical PV power plant will have dierent outcomes than demonstrated here. e
paucity in data on the physical eects of this important and growing land use and land cover change warrants
more studies from representative ecosystems.
What are the human implications of a PVHI, and how might we mitigate these
With the growing popularity of renewable energy production, the boundaries between residential areas and
larger-scale PV installations are decreasing. In fact, closer proximity with residential areas is leading to increased
calls for zoning and city planning codes for larger PV installations32,33, and PVHI-based concerns over potential
reductions in real estate value or health issues tied to Human ermal Comfort (HTC)34. Mitigation of a PVHI
eect through targeted revegetation could have synergistic eects in easing ecosystem degradation associated
with development of a utility scale PV site and increasing the collective ecosystem services associated with an
area4. But what are the best mitigation measures? What tradeos exist in terms of various means of revegetating
degraded PV installations? Can other albedo modications be used to moderate the severity of the PVHI?
Figure 3. (Le) Average monthly levels of Photovoltaic Heat Islanding (ambient temperature dierence
between PV installation and desert) and Urban Heat Islanding (ambient temperature dierence between
the urban parking lot and the desert). (Right) Average night and day temperatures for four seasonal periods,
illustrating a signicant PVHI eect across all seasons, with the greatest inuence on ambient temperatures at
Scientific RepoRts | 6:35070 | DOI: 10.1038/srep35070
To fully contextualize these ndings in terms of global warming, one needs to consider the relative signi-
cance of the (globally averaged) decrease in albedo due to PV power plants and their associated warming from the
PVHI against the carbon dioxide emission reductions associated with PV power plants. e data presented here
represents the rst experimental and empirical examination of the presence of a heat island eect associated with
PV power plants. An integrated approach to the physical and social dimensions of the PVHI is key in supporting
decision-making regarding PV development.
Site Description. We simultaneously monitored a suite of sites that represent the traditional built urban
environment (a parking lot) and the transformation from a natural system (undeveloped desert) to a 1 MW
PV power plant (Fig.4; Map data: Google). To minimize confounding eects of variability in local incoming
energy, temperature, and precipitation, we identied sites within a 1 km area. All sites were within the boundaries
of the University of Arizona Science and Technology Park Solar Zone (32.092150°N, 110.808764°W; elevation:
888 m ASL). Within a 200 m diameter of the semiarid desert site’s environmental monitoring station, the area is
composed of a sparse mix of semiarid grasses (Sporobolus wrightii, Eragrostis lehmanniana, and Muhlenbergia
porteri), cacti (Opuntia spp. and Ferocactus spp.), and occasional woody shrubs including creosote bush (Larrea
tridentata), whitethorn acacia (Acacia constricta), and velvet mesquite (Prosopis velutina). e remaining area is
bare soil. ese species commonly co-occur on low elevation desert bajadas, creosote bush ats, and semiarid
grasslands. e photovoltaic installation was put in place in early 2011, three full years prior when we initiated
monitoring at the site. We maintained the measurement installations for one full year to capture seasonal var-
iation due to sun angle and extremes associated with hot and cold periods. Panels rest on a single-axis tracker
system that pivot east-to-west throughout the day. A parking lot with associated building served as our “urban
site and is of comparable spatial scale as our PV site.
Monitoring Equipment & Variables Monitored. Ambient air temperature (°C) was measured with a
shaded, aspirated temperature probe 2.5 m above the soil surface (Vaisala HMP60, Vaisala, Helsinki, Finland in
the desert and Microdaq U23, Onset, Bourne, MA in the parking lot). Temperature probes were cross-validated
for precision (closeness of temperature readings across all probes) at the onset of the experiment. Measurements
of temperature were recorded at 30-minute intervals throughout a 24-hour day. Data were recorded on a
data-logger (CR1000, Campbell Scientic, Logan, Utah or Microstation, Onset, Bourne, MA). Data from this
Figure 4. Experimental sites. Monitoring a (1) natural semiarid desert ecosystem, (2) solar (PV)
photovoltaic installation, and (3) an “urban” parking lot – the typical source of urban heat islanding –
within a 1 km2 area enabled relative control for the incoming solar energy, allowing us to quantify variation
in the localized temperature of these three environments over a year-long time period. e Google Earth
image shows the University of Arizona’s Science and Technology Park’s Solar Zone.
Scientific RepoRts | 6:35070 | DOI: 10.1038/srep35070
instrument array is shown for a yearlong period from April 2014 through March 2015. Data from the parking lot
was lost for September 2014 because of power supply issues with the datalogger.
Statistical analysis. Monthly averages of hourly (on-the-hour) data were used to compare across the nat-
ural semiarid desert, urban, and PV sites. A Photovoltaic Heat Island (PVHI) eect was calculated as dierences
in these hourly averages between the PV site and the natural desert site, and estimates of Urban Heat Island
(UHI) eect was calculated as dierences in hourly averages between the urban parking lot site and the natural
desert site. We used midnight and noon values to examine maximum and minimum, respectively, dierences
in temperatures among the three measurement sites and to test for signicance of heat islanding at these times.
Comparisons among the sites were made using Tukey’s honestly signicant dierence (HSD) test35. Standard
errors to calculate HSD were made using pooled midnight and noon values across seasonal periods of winter
(January-March), spring (April-June), summer (July-September), and fall (October-December). Seasonal anal-
yses allowed us to identify variation throughout a yearlong period and relate patterns of PVHI or UHI eects
with seasons of high or low average temperature to examine correlations between background environmental
parameters and localized heat islanding.
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e authors thank Ken Marcus for access to the University of Arizona Solar Zone and the Science and Technology
Park and to Tucson Electric Power for access to their PV installation. This research was supported by the
University of Arizona Institute of the Environment and the Oce of Research & Development through the TRIF-
funded Water, Environmental and Energy Solutions initiative.
Author Contributions
G.A.B.-G., R.L.M. and N.A.A. established research sites and installed monitoring equipment. G.A.B.-G. directed
research and R.L.M. conducted most site maintenance. G.A.B.-G., N.A.A., A.D.C. and M.A.P.-Z. led eorts to
secure funding for the research. All authors discussed the results and contributed to the manuscript.
Additional Information
Competing nancial interests: e authors declare no competing nancial interests.
How to cite this article: Barron-Gaord, G. A. et al. e Photovoltaic Heat Island Eect: Larger solar power
plants increase local temperatures. Sci. Rep. 6, 35070; doi: 10.1038/srep35070 (2016).
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... Solar photovoltaic (PV) is the most potential renewable energy (Choi et al. 2020;Pogson et al. 2013). In recent years, the number of large-scale PV installations has shown an exponential growth trend (Barron-Gafford et al. 2016), which is likely to continue (Armstrong et al. 2016). During the period from 2009 to 2035, the predicted demand for the world's major energies will increase by 40%, while the contribution of wind and solar energy will reach 600% (Armstrong et al. 2014). ...
... However, some studies have also shown that PV infrastructure is conducive to maintaining soil moisture and improving the water use efficiency of biomass and plants ( Barron-Gafford et al. 2019;Hassanpour Adeh et al. 2018;Marrou et al. 2013). In addition, there is an increase in the air temperature above the PV array compared to the surrounding natural area due to the change in land-use type, vegetation coverage, and albedo (Barron-Gafford et al. 2016). Barron-Gafford et al.'s (2016) study showed that large-scale PV power plants could cause the heat island effect, and the temperature over the solar PV array increased by 3-4 °C compared with the wildland at night. ...
... On the daily scale, the temperature difference between inside and outside PV increased with the amplification of solar radiation, and the temperature difference in September was as high as 0.49 °C. Studies have also shown that onshore PV power plants have a significant heating effect on ambient air at an elevation of 2 m during the day (Barron-Gafford et al. 2016, Broadbent et al. 2019, Chang et al. 2018, Yang et al. 2015. However, Liu et al. (2018) studied eight different floating PV plans in Singapore's Tengeh Reservoir in which the water surface temperature was 1-3 °C lower than onshore, which may be related to the tilt of PV panels, water area, and PV power plant. ...
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Photovoltaic (PV) power plants have shown rapid development in the renewable sector, but the research areas have mainly included land installations, and the study of fishery complementary photovoltaic (FPV) power plants has been comparatively less. Moreover, the mechanism of local microclimate changes caused by FPV panels has not been reported. This work revealed this mechanism using a physical model to illustrate the impact of FPV power plants in a lake on the environment. The results indicated that the lake becomes a heat sink after deploying the PV panel on water. The comprehensive albedo (0.082) decreased by 18.8% relative to the free water surface (0.101). The water energy change was dominated by the water–air vapor pressure deficit. In addition, the FPV panels had a heating effect on the ambient environment; however, the range of this effect was related to the water depth. The installation had an obvious heating effect on surface water.
... Solar energy is one of the most promising renewable energy sources because of its ubiquity and sustainability [2e6]. The capacity of utility-scale solar photovoltaic (PV) installations has exponentially increased [7]. Solar energy is expected to compose the majority of renewable energy production worldwide [8], and fulfill 20%e29% (32,700e133,000 GW) of global electricity demand by 2100 [9,10]. ...
... The magnitude of the heating effect varied from 0.05 C to 2.39 C during the study period, and the heating effect increased with an increase in the inside and outside FPV temperature. Barron-Gafford et al. [7] studied the effect of the PV heat island effect on local temperatures, and their results are consistent with those of this study. However, the heating effect was only explained by 26% (r 2 ¼ 0.26) through the daily maximum air temperature. ...
... Our results still show a heating effect at 10 m is not obvious. However, the heating effect in the daytime is inconsistent with the findings of Jiang et al. [37], Barron-Gafforf et al. [7], Chang et al. [39], Yang et al. [40], and Broadbent et al. [38]. However, the PV array on ambient effect depend on ambient air differs, and the condition of underlying surface. ...
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Solar energy plays an essential role in achieving carbon goals and mitigating climate change. Therefore, solar power plants are rapidly developing in the renewable energy sector. However, many reports of solar power plants are on land, and extremely limited observational research has been conducted on the impacts of fishery complementary photovoltaic power plants (FPVs) on near-surface meteorology and surface energy. This study selected two adjacent eddy covariance observational towers at the fishery complementary photovoltaic power plant (FPV) in Yangzhong, Jiangsu Province, China, to explore this topic. The results indicated that the percent frequency of east wind (<4 m s⁻¹) at 2 m decreased by 25.3% in the FPV site compared with the reference site. The FPV array has not an obvious heating effect on the ambient environment. The average air temperature difference in the two sites at 2 m and 10 m was 0.3 K and 0.1 K, respectively, during the heating period. The net radiation increased by 47.8 W m⁻² in the two sites. The sensible heat increased by 7.9 W m⁻² due to the heating effect. The latent heat in the two sites is contrary to the sensible heat (−13.0 W m⁻²). The difference in the water storage heat is 32.18 W m⁻², which implies that the water absorbs higher heat in the FPV site than in the reference site. This work illustrated the importance of observational experiments to animate process-based understanding combined with FPV systems and provides a scientific basis for establishing FPV energy balance models based on observations that may be used to reveal the impact of utility-scale FPV deployment on climatic effects.
... Recently, the solar photovoltaic (PV) plant areas have been increasing globally, as they are seen as a valid source of renewable energy production [1][2][3][4][5][6]. These PV panels contain directly produced energy from the incoming solar radiation [7][8][9]. The PV will be influenced and attributed on the amount of solar radiation on the existing local climate system [7,9,10]. ...
... These PV panels contain directly produced energy from the incoming solar radiation [7][8][9]. The PV will be influenced and attributed on the amount of solar radiation on the existing local climate system [7,9,10]. This solar radiation also a crucial part of reference evapotranspiration (ETo). ...
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Large-scale photovoltaic (PV) power plants may affect the hydrological cycle in all its components. Among the various components, evapotranspiration is one of the most important. As a preliminary step for assessing the impacts of PV plants on evapotranspiration, in this study, we performed an evaluation study of methods for estimating reference evapotranspiration (ETo). FAO and ASCE recommend the Penman–Monteith (PM) method for the estimation of ETo when the data for all involved variables are available. However, this is often not the case, and different empirical methods to estimate ETo, requiring mainly temperature data, need to be used. This study aimed at assessing the performance of different temperature- and radiation-based empirical ETo estimation methods against the standardized PM ETo method in an experimental photovoltaic power plant in Piazza Armerina, Sicily, Italy, where a meteorological station and a set of sensors for soil moisture were installed. The meteorological data were obtained from the Lab from July 2019 to end of January 2022. By taking the ETo estimations from the PM method as a benchmark, the study assessed the performance of various empirical methods. In particular, the following methods were considered: Hargreaves and Samani (HS), Baier and Robertson (BR), Priestley and Taylor (PT), Makkink (MKK), Turc (TUR), Thornthwaite (THN), Blaney and Criddle (BG), Ritchie (RT), and Jensen and Haise (JH) methods, using several performance metrics. The result showed that the PT is the best method, with a Nash–Sutcliffe efficiency (NSE) of 0.91. The second method in order of performance is HS, which, however, performs significantly worse than PT (NSE = 0.51); nevertheless, this is the best among methods using only temperature data. BG, TUR, and THN underestimate ETo, while MKK, BG, RT, and JH showed overestimation of ETo against the PM ETo estimation method. The PT and HS methods are thus the most reliable in the studied site.
... APV systems were pioneered in the 1980s (Goetzberger and Zastrow [19]) and have steadily grown as photovoltaic systems have become more robust and inexpensive. We refer the reader to [1][2][3]6,8,9,12,[14][15][16]19,22,26,34,36,[38][39][40][41]47,52,55,56,58] for a broad survey of such systems. 2 Regardless of the exact type of blended system, there is a necessity to optimize these complex heterogeneous systems so that they operate smoothly. ...
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Energy Management Systems (EMS) refer to frameworks that control the energy generation, transmission and storage for multiple devices which are coupled together. These can range from nationwide grids, utility-scale systems, microgrids, data-centers to electric vehicles and can consist of renewable energy sources, fossil-fuel energy, transmission lines, batteries, generators, ultracapacitors and transformers, to name a few. The goals of such systems are typically to balance the load, guarantee the power supply for each device, maximize overall efficiency and to minimize overall losses. Remarkable increases in desktop computing have opened up the possibility for researchers and practitioners to construct and tailor simulation paradigms for their own specific system’s needs. Accordingly, the objective of this work is to develop a flexible and rapidly computable framework that researchers can easily alter and manipulate for their specific system. The approach taken in this work is to study a model problem, consisting of an energy supplier and a large number of strongly coupled devices with specific needs. The framework computes an energy balance for each device in the system and ascertains what the energy supplier must deliver or extract from the device to allow it to meet a specific target state while accounting for transmission losses. A digital-twin is created of such a system that is capable of running at extremely high speeds and which is coupled to a genetic-based machine-learning algorithm in order to optimize the operation of the supplier. Numerical examples are provided to illustrate the approach.
... The most significant increase in humidity was 5.00% and 4.76% (respectively) in winter for reference and transition areas. It was found that diurnal air temperature and humidity values inside the PV power plant were higher than outside the PW power plant.Fan and Huang[28] investigated the impact of PVPP installation increases on surface spectral reflectance for Qinghai province, China, using the satellite-based Moderate module shading have been noted (increase of food production; decrease of plant drought and PV module heat stresses).Again, Barron-Gafford et al.[8] contributed to the studies in the literature that previously examined the UHI-like PVHIE mostly with theoretical or simulation methods by utilizing a field study they conducted experimentally at the University of Arizona, USA. The authors recorded higher temperatures of 3-4°C at a PVPP site than the neighboring wildlands at night.Fthenakis and Yu[30] examined the impacts of large-scale PVPPs on the local microclimate using computational fluid dynamics. ...
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Today, solar energy conversion technologies, which are among the methods of obtaining renewable, sustainable, and clean energy, show rapid development. One of the most common technologies is Photovoltaic Solar Power Plant (PVPP), which provides electricity by direct conversion of the energy carried by the sunlight (or daylight). These power plants are socially accepted in environmentally-friendly and economical energy production. However, there are some debates about the environmental impacts of these power plants. One of the issues at the focus of these debates is whether dark-colored photovoltaic solar module (panel) arrays in large numbers used to build these power plants alter the natural ground reflectivity (albedo) of the land where they are installed. For this reason, they may also affect the local air temperature cycles of the region where they are located. This environmental problem, referred to as the Photovoltaic Heat Island Effect (PVHIE) in the literature, arises from the optical and thermal properties of photovoltaic modules interacting with their close environment. A three-year field project and study was carried out to observe this effect in a PVPP constructed in the Sekbandemirli rural area in the Tavşanlı district of the Kütahya province in Turkey. The relevant weather data collected by the meteorological stations installed on specific locations inside and outside Sekbandemirli PVPP were analyzed using statistical (ANOVA and Tukey’s HSD), correlational (Pearson and Spearman), graphical (percentage column distribution, daily and monthly line charts, and representative illustrations) and simulation-based (the microclimate simulation software ENVI-met) methods. Accordingly, the heat island formations, which can be expressed as "transient", whose frequency of occurrence changes daily and seasonally, have been found at the Sekbandemirli PVPP field center. The air temperatures recorded at the field center show the differences between “(-3) – 6°C” compared to those recorded at the reference location outside the field. The higher daytime ambient air temperatures up to 6°C difference at the field center significantly indicate the evident (and positive) PVHI formations, although a less effective (up to -3°C) cooling effect (negative PVHIE) prevails mostly at nighttimes. This thesis is the first study on PVHIE in Turkey and the world, in line with the methods used within its content.
Based on the meteorological observation data of air temperature, surface temperature and albedo data retrieved from remote sensing images inside and outside the photovoltaic station, as well as the measured soil moisture content and bulk density at different locations of the photovoltaic power station in 2019, the impact of large-scale desert photovoltaic power plants on climate and environment was studied. The results show that air temperature, surface temperature and albedo inside the photovoltaic power station are lower than those outside the station, which are obvious in winter and not obvious in summer. Therefore, the photovoltaic power station is a cold source and an energy sink. The soil moisture content under and between the photovoltaic modules is larger than other sampling points, and the soil bulk density gradually decreases with the distance from the center of the photovoltaic power station. Therefore, future plans for desert photovoltaic power station construction should take into account the impacts on local climate and environment.
Purpose Bahrain has set a national target of achieving carbon neutrality by 2060, with an interim goal of a 30% reduction in CO 2 e emissions by 2035. The aim of this policy brief is to provide insights on how carbon neutrality in Bahrain can be achieved. Design/methodology/approach A review of literature related to climate change mitigation in general, and that related to Bahrain in particular, was carried out. Findings Given that the carbon intensity of Bahrain's economy is relatively high, achieving carbon neutrality requires not only technologies for reducing CO 2 e emissions at the source and enhanced carbon sinks, but it also requires the introduction of a circular economy culture and efforts to foster pro-environmental behavior within the population. The involvement of different stakeholders in the journey toward carbon neutrality is critical, along with the formulation of requisite policies regulating the roles of technology, behavior and research. Originality/value Pathways to achieve carbon neutrality in Bahrain were explored, and areas for policy focus were recommended.
Many cities are facing urban heat problems, the combined effect of heatwaves under global climate change, and local warming associated with urbanization, resulting in severe environmental, economic, social, and health impacts. It is urgent to address urban heat problems. Existing studies indicate buildings are an important cause of urban heat, while buildings are favorable spaces to address urban heat problems through built environment decarbonization and the implementation of urban cooling strategies. Green building (GB) which has been recognized as an innovative philosophy and practice in the building sector, is proposed to address urban heat challenges. However, existing studies have offered a limited understanding of GB-based urban heat mitigation and adaptation. Therefore, this study aims to examine how the GBs contribute to urban heat mitigation and adaptation. In particular, this study analyses the contribution of buildings to urban heat problems in aspects of carbon emissions and the extensive urban modifications towards artificial landscapes and discusses the possible impacts caused by urban heat problems. Afterward, this study develops the framework of GB’s responses to urban heat problems in global warming mitigation, local warming mitigation, and urban heat adaptation. Based on this, such responses are analyzed in aspects of site planning, outdoor environments, transportation, building design, energy efficiency, water efficiency, material efficiency, indoor environmental quality, operation management, construction, and maintenance following the whole life cycle perspective. This paper helps understand how GB techniques contribute to urban heat mitigation and adaptation and provides a reference to the revision of the GB assessment system for addressing urban heat problems.
Agrivoltaic systems have the potential to maximize the usefulness of spaces in building rooftops. Urban farming systems improve the microclimatic conditions, which are beneficial to solar photovoltaic (PV) systems, as they lower the operating temperatures, resulting in a higher operating efficiency. Microclimate simulations by means of ENVI-met simulation showed that between 0800 h and 1800 h, PV temperatures in the plot that has crops below the PV system were on average lower by 2.83 °C and 0.71 °C as compared without crops on a typical sunny and cloudy day, respectively. Hence, we may see PV efficiency performance improvement of 1.13–1.42% and 0.28–0.35% on a sunny day and cloudy day, respectively. Data collected from a physical prototype of an agrivoltaic system suggested that evaporative cooling was responsible for the reduction in ambient temperatures. The presence of crops growing underneath the PV canopy resulted in the agrivoltaic prototype generating between 3.05 and 3.2% more energy over the day as compared to a control system with no crops underneath.
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Objetivo: identificar de qué manera los megaproyectos de energía eólica y fotovoltaica contribuyen a la fragmentación social en las zonas rurales, para reconocerlos como iniciativas que forman parte de las problemáticas actuales de la Nueva Ruralidad. Metodología: es un estudio de alcance exploratorio que articula un análisis documental con la experiencia profesional sobre el sector energético para realizar un análisis socioespacial sobre 12 parques eólicos y 11 fotovoltaicos identificados en el estado de Yucatán. Este trabajo se fortaleció con una matriz derivada del análisis documental de 24 evaluaciones socioambientales de dichos megaproyectos. Resultados: los 23 megaproyectos presentes en Yucatán afectan 260 parcelas, correspondientes a 16 núcleos agrarios, mismos que aglutinan a 5,851 ejidatarios. La distribución de sus beneficios económicos así como su impacto socioterritorial generarán problemáticas que incrementan la diferenciación social entre la población rural agrícola y la no agrícola. Limitaciones: es necesario que futuras investigaciones puedan ampliar y fortalecer las propuestas conceptuales de desagrarización y fragmentación social. Conclusiones: los megaproyectos de energía eólica y fotovoltaica representan una tecnología innovadora basada en la explotación de los recursos naturales. Su instalación y operación supone el alquiler de terrenos que antes tenían fines agropecuarios, lo cual implica no solo un drástico cambio en las actividades económicas rurales, sino la transformación de la clásica noción de campesino y agricultor en un productor pluriactivo donde el arrendamiento de tierras para desarrollar actividades no agrícolas cambia profundamente la composición del ingreso familiar. Esta transformación pone en tensión las estructuras agrarias sustentadas en la propiedad social sobre la tierra.
Conference Paper
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The promise for harnessing solar energy being hampered by cost, triggered efforts to reduce them. As a consequence low-efficiency, low-cost photovoltaics (PV) panels prevail. Conversely, in the traditional energy sector efficiency is extremely important due to the direct costs associated to fuels. This also affects solar energy due to the radiative forcing caused by the dark solar panels. In this paper we extend the concept of energy payback time by including the effect of albedo change, which gives a better assessment of the system sustainability. We present an analysis on the short and medium term climate forcing effects of different solar collectors in Riyadh, Saudi Arabia and demonstrate that efficiency is important to reduce the collector area and cost. This also influences the embodied energy and the global warming potential. We show that a placement of a high concentration photovoltaic thermal solar power station outside of the city using a district cooling system has a double beneficial effect since it improves the solar conversion efficiency and reduces the energy demand for cooling in the city. We also explain the mechanisms of the current economic development of solar technologies and anticipate changes.
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The production of solar energy in cities is clearly a way to diminish our dependency to fossil fuels, and is a good way to mitigate global warming by lowering the emission of greenhouse gases. However, what are the impacts of solar panels locally? To evaluate their influence on urban weather, it is necessary to parameterize their effects within the surface schemes that are coupled to atmospheric models. The present paper presents a way to implement solar panels in the Town Energy Balance scheme, taking account of the energy production (for thermal and photovoltaic panels), the impact on the building below and feedback toward the urban micro-climate through radiative and convective fluxes. A scenario of large but realistic deployment of solar panels on the Paris metropolitan area is then simulated. It is shown that solar panels, by shading the roofs, slightly increases the need for domestic heating (3%). In summer, however, the solar panels reduce the energy needed for air-conditioning (by 12%) and also the Urban Heat Island (UHI): 0.2 K by day and up to 0.3 K at night. These impacts are larger than those found in previous works, because of the use of thermal panels (that are more efficient than photovoltaic panels) and the geographical position of Paris, which is relatively far from the sea. This means that it is not influenced by sea breezes, and hence that its UHI is stronger than for a coastal city of the same size. But this also means that local adaptation strategies aiming to decrease the UHI will have more potent effects. In summary, the deployment of solar panels is good both globally, to produce renewable energy (and hence to limit the warming of the climate) and locally, to decrease the UHI, especially in summer, when it can constitute a health threat.
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The deployment of renewable energy systems, such as solar energy, to achieve universal access to electricity, heat and transportation, and to mitigate climate change is arguably the most exigent challenge facing humans today(1-4). However, the goal of rapidly developing solar energy systems is complicated by land and environmental constraints, increasing uncertainty about the future of the global energy landscape(5-7). Here, we test the hypothesis that land, energy and environmental compatibility can be achieved with small-and utility-scale solar energy within existing developed areas in the state of California (USA), a global solar energy hotspot. We found that the quantity of accessible energy potentially produced from photovoltaic (PV) and concentrating solar power (CSP) within the built environment ('compatible') exceeds current statewide demand. We identify additional sites beyond the built environment ('potentially compatible') that further augment this potential. Areas for small-and utility-scale solar energy development within the built environment comprise 11,000-15,000 and 6,000 TWh yr(-1) of PV and CSP generation-based potential, respectively, and could meet the state of California's energy consumptive demand three to five times over. Solar energy within the built environment may be an overlooked opportunity for meeting sustainable energy needs in places with land and environmental constraints.
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As utility-scale solar energy (USSE) systems increase in size and numbers globally, there is a growing interest in understanding environmental interactions between solar energy development and land-use decisions. Maximizing the efficient use of land for USSE is one of the major challenges in realizing the full potential of solar energy, however, the land-use efficiency (LUE; Wm-2) of USSE remains ambiguous. We quantified the capacity-based LUE of 183 USSE installations (> 20 MW; planned, under construction, and operating) using California as a case study. In California, USSE installations are concentrated in the Central Valley and interior regions of southern California and have a LUE of 35.0 Wm-2. The installations occupy approximately 86,000 hectares and more land is allocated for photovoltaic schemes (72,294 ha) than for concentrating solar power (13,604 ha). Photovoltaic installations are greater in abundance (93%) than concentrating solar power, but technology type and nameplate capacity has no impact on capacity-based LUE. More USSE installations are on private land (80%) and have a significantly greater LUE (35.8 Wm-2) than installations on public land (25.4 Wm-2). Our findings can be used to better understand and improve the LUE of USSE, thereby maximizing economic, energetic, and environmental returns on investments.
This Intergovernmental Panel on Climate Change Special Report (IPCC-SRREN) assesses the potential role of renewable energy in the mitigation of climate change. It covers the six most important renewable energy sources - bioenergy, solar, geothermal, hydropower, ocean and wind energy - as well as their integration into present and future energy systems. It considers the environmental and social consequences associated with the deployment of these technologies, and presents strategies to overcome technical as well as non-technical obstacles to their application and diffusion. SRREN brings a broad spectrum of technology-specific experts together with scientists studying energy systems as a whole. Prepared following strict IPCC procedures, it presents an impartial assessment of the current state of knowledge: it is policy relevant but not policy prescriptive. SRREN is an invaluable assessment of the potential role of renewable energy for the mitigation of climate change for policymakers, the private sector, and academic researchers.
Urban heat island is the more documented phenomenon of climate change. Information on the magnitude and the characteristics of the canopy layer urban heat island measured in 101 cities and regions of Asia and Australia and collected through 88 scientific articles, are compiled, evaluated and presented. Data are classified in several clusters according to the experimental protocol used and the type of statistical information reported regarding the magnitude of the urban heat island. Results and detailed analysis are given for each defined cluster. Very significant differences on the UHI intensity are found between the clusters and analyzed in detail. The detailed impact of the main weather parameters and conditions on the magnitude of the UHI is also investigated. The specific influence of anthropogenic thermal fluxes as well as of the urban morphological and construction characteristics to UHI is thoroughly examined. The relation between the UHI intensity and the city size is assessed and global relationships of UHI as a function of the urban population are proposed. The seasonal and diurnal variability of the UHI is analyzed and discussed while specific features and conditions like the urban heat island characteristics in coastal cities and the existence of daytime cool islands are explored. Finally, the impact of the selected reference station and its characteristics is considered. Copyright © 2015 Elsevier B.V. All rights reserved.
Among the many benefits of solar photovoltaic (PV) systems, the direct effects are those of providing local power and the indirect ones include avoided generation from fossil-fuel power plants. The latter translate into reduced emissions of greenhouse gas (thus reduced radiative forcing) and other pollutants, such as ozone precursors (thus improved air quality). Because large-scale PV deployments can alter the radiative balance at the surface-atmosphere interface, they can exert certain impacts on the temperature and flow fields.In this analysis, meteorological modeling was performed for the Los Angeles region as a case study to evaluate the potential atmospheric effects of solar PV deployment. The simulations show no adverse impacts on air temperature and urban heat islands from large-scale PV deployment. For the range of solar conversion efficiencies currently available or expected to become attainable in the near future, the deployment of solar PV can cool the urban environment. The cooling can reach up to 0.2 C in the Los Angeles region. Under hypothetical future-year scenarios of cool cities (urban areas with extensive implementations of highly-reflective roofs and pavements) and high-density deployments of urban solar PV arrays, some adverse impacts (0.1 C or less in warming) might occur. However, such extreme high-density deployments of cool surfaces are not expected and thus the warming effects are unlikely to result.
Conference Paper
Large-scale solar power plants are being built at a rapid rate, and are setting up to use hundreds of thousands of acres of land surface. The thermal energy flows to the environment related to the operation of such facilities have not, so far, been addressed comprehensively. We are developing rigorous computational fluid dynamics (CFD) simulation capabilities for modeling the air velocity, turbulence, and energy flow fields induced by large solar PV farms to answer questions pertaining to potential impacts of solar farms on local microclimate. Using the CFD codes Ansys CFX and Fluent, we conducted detailed 3-D simulations of a 1 MW section of a solar farm in North America and compared the results with recorded wind and temperature field data from the whole solar farm. Both the field data and the simulations show that the annual average of air temperatures in the center of PV field can reach up to 1.9°C above the ambient temperature, and that this thermal energy completely dissipates to the environment at heights of 5 to 18 m The data also show a prompt dissipation of thermal energy with distance from the solar farm, with the air temperatures approaching (within 0.3°C) the ambient at about 300 m away of the perimeter of the solar farm. Analysis of 18 months of detailed data showed that in most days, the solar array was completely cooled at night, and, thus, it is unlikely that a heat island effect could occur. Work is in progress to approximate the flow fields in the solar farm with 2-D simulations and detail the temperature and wind profiles of the whole utility scale PV plant and the surrounding region. The results from these simulations can be extrapolated to assess potential local impacts from a number of solar farms reflecting various scenarios of large PV penetration into regional and global grids.
This paper briefly considers the recent dramatic reductions in the underlying costs and market prices of solar photovoltaic (PV) systems, and their implications for decision-makers. In many cases, current PV costs and the associated market and technological shifts witnessed in the industry have not been fully noted by decision-makers. The perception persists that PV is prohibitively expensive, and still has not reached 'competitiveness'. The authors find that the commonly used analytical comparators for PV vis a vis other power generation options may add further confusion. In order to help dispel existing misconceptions, some level of transparency is provided on the assumptions, inputs and parameters in calculations relating to the economics of PV. The paper is aimed at informing policy makers, utility decision-makers, investors and advisory services, in particular in high-growth developing countries, as they weigh the suite of power generation options available to them.
We used 1954–1983 surface temperature from 42 Chinese urban (average population 1.7*106) and rural (average population 1.5*105) station pairs to study the urban heat island effects. Despite the fact that the rural stations are not true rural stations, the magnitude of the heat islands was calculated to average 0.23 °C over the thirty-year period with a minimum value during the 1964–1973 decade and maximum during the most recent decade. The urban heat islands were found to have seasonal dependence which varied considerably across the country. The urban heat islands also had a strong regional dependence with the Northern Plains dominating the magnitude of the heat islands. The changes in heat island intensity over three decades studied suggest a general increase in heat island intensity of about 0.1°C, but this has not been constant in time. These results suggest that caution must be exercised when attributing causes to observed trends when stations are located in the vicinity of metropolitan areas.