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AIP Conference Proceedings 2361, 030002 (2021); https://doi.org/10.1063/5.0054674 2361, 030002
© 2021 Author(s).
Evolution of agrivoltaic farms in Japan
Cite as: AIP Conference Proceedings 2361, 030002 (2021); https://doi.org/10.1063/5.0054674
Published Online: 28 June 2021
Makoto Tajima, and Tetsunari Iida
Evolution of Agrivoltaic Farms in Japan
Makoto Tajimaa) and Tetsunari Iidab)
Institute for Sustainable Energy Policies. iTEX bldgs., 16-16, Yotsuya San-ei-cho, Shinjuku-ku, Tokyo
160-0008 JAPAN
a)Corresponding author: tajima_makoto@isep.or.jp
b)tetsu@isep.or.jp
Abstract. Development of agrivoltaics in Japan started in 2004 in Chiba Prefecture initiated by Akira Nagashima. Today,
1,992 agrivoltaic farms (560 ha) exist throughout Japan except one prefecture out of 47 prefectures. Most agrivoltaics in
Japan is small-scale less than 0.1 ha. It is estimated that total power generated by agrivoltaics is 500,000 to 600,000 MWh
or 0.8% of the total power generated by photovoltaics in Japan in 2019. Farmland must be converted to non-agricultural
use to install photovoltaics, in which agrivoltaics has an advantage over solar parks applicable to all 5 classes of farmland.
Increase of devastated and abandoned farmland is a grave concern for the Japanese agriculture and agrivoltaics is expected
to contribute to solve this issue. Over 120 crops are grown in agrivoltaics in Japan and for 69% of cases, cultivated crop is
changed upon installation of agrivoltaics, which is causing concern that it may disrupt small, fixed markets of those crops.
Shading rate in agrivoltaics ranges from 10 to 100% with its median at 30 to 40%. The choice of shading rate is made
according to light saturation point of the crop, but a high shading rate is often determined first to maximize profit from
electricity sale, because it is much greater than the one from agriculture itself, then suitable crop for that shading rate is
chosen. Agrivoltaic development in Japan took off after the introduction of feed-in tariff (FIT) in 2012. FIT was
significantly effective in policy impact compared to RPS system previously acquired in Japan, increasing renewable energy
supply in Japan by 76% from 2012 to 2019. Photovoltaics has been a driving force increased from 7,600 GWh to 77,000
GWh during the same period. Two directives from the Ministry of Agriculture, Forestry and Fisheries (MAFF), one in
March 2013 and another in May 2018, institutionalized agrivoltaics and promoted its development. The second amendment
of FIT Law in June 2020, which will be enforced in April 2022, further paved the way for agrivoltaics preferentially treating
it. Agrivoltaics is expected play an important role to revitalize the Japanese agriculture including reclamation of devastated
or abandoned farmland, as being included in the above-mentioned policies. If all abandoned farmland were converted to
agrivoltaic farms, 280 GW of electricity could be produced. The potential of agrivoltaics in 8 prefectures in Kanto region
is estimated at least 15 to 39 GW. Emerging innovative agrivoltaics, such as one we see in a high value-added tea
agrivoltaics in Shizuoka prefecture, is an economically and environmentally sound business model, which we may want to
replicate elsewhere.
HISTORY AND CURRENT SITUATION
Origin
Development of agrivoltaic farms in Japan all started from Akira Nagashima’s initiatives. He coined the term
“solar sharing (synonymous to agrivoltaics)” in 2003 and made its patent free for public use in 2005. Narrow-width
24-cell PV module was devised by him to mitigate shading effect and splash erosion to the crops under the PV panels.
The first agrivoltaic farm in Japan was established by him in Chiba prefecture in 2004. The book written by Nagasihma
comprehensively described “solar sharing,” originally published in Japanese1 in 2015 (also available in English2 in
2020), became a bible for the early adopter of agrivoltaics in Japan.
AgriVoltaics2020 Conference
AIP Conf. Proc. 2361, 030002-1–030002-9; https://doi.org/10.1063/5.0054674
Published by AIP Publishing. 978-0-7354-4104-0/$30.00
030002-1
The Number and Scale
As of March 2019, total number of 1,992 agrivoltaic farms (560.0 ha) is registered under the Ministry of
Agriculture, Forestry and Fisheries (MAFF), spreading to 46 prefectures out of 47 throughout Japan, except Toyama
prefecture (Table 1). Chiba Prefecture, the origin of agrivoltaics in Japan, has the largest number of 298 agrivoltaic
farms (Table 1).
The most agrivoltaic farms in Japan are small-scale. Out of 755 agrivoltaic farms established by May 2018, 65%
or 490 farms were less than <0.1 ha, followed by 0.1 to 0.3 ha (24% or 178 farms), 0.3 to 0.5 ha (4% or 27 farms),
0.5 to 1 ha (5% or 34 farms), and >1 ha (3% or 26 farms).4 It is natural to see the scale is skewed towards the lower
end, since most farms in Japan are small-scale. Some 623,900 or 52% of farm management entities out of 1,188,800
owns less than 1 ha of agricultural field, followed by 1 to 5 ha (38% or 457,400 farms), 5 to 10 ha (4% or 49,800
farms), 10 to 20 ha (1% or 11,500 farms), and more than 30 ha (2% or 18,800 farms).5
TABLE 1. The number of officially registered agrivoltaic farms in Japan by prefecturea
AABb Prefecture
Agrivoltaic
farms AABb Prefecture
Agrivoltaic
farms AABb Prefecture
Agrivoltaic
farms
Hokkaido Hokkaido 6 Shizuoka 264 Shikoku Oka
y
ama 9
Tohoku Aomori 10 Hokuriku Nii
g
ata 27 Hiroshima 31
Iwate 13 To
y
ama 0 Yama
g
uchi 2
Mi
y
a
g
i 29 Ishikawa 3 Tokushima 131
Akita 12 Fukui 16 Ka
g
awa 45
Yama
g
ata 34 Tokai Gifu 46 Ehime 32
Fukushima 75 Aichi 47 Kochi 6
Kanto Ibaraki 111 Mie 36 Kyushu Fukuoka 15
Tochi
g
i 19 Kinki Shi
g
a 17 Sa
g
a 6
Gunma 196 K
y
oto 17 Na
g
asaki 3
Saitama 100 Osaka 4 Kumamoto 36
Chiba 298 H
y
o
g
o 39 Oita 6
Tok
y
o 4 Nara 30 Mi
y
azaki 10
Kana
g
awa 31 Waka
y
ama 23 Ka
g
oshima 9
Yamanashi 67 Chugoku Tottori 6 Okinawa Okinawa 19
Na
g
ano 34 Shimane 18 Total 1,992
a Reference 3.
b AAB = Agricultural Administration Bureau
We can only infer the installed capacity of agrivoltaics in Japan since there is no official statistics available. A
reasonable estimate would be 500 to 600 MW (or 500,000 to 600,000 MWh) based on the total installed area of
officially registered agrivoltaic farms,6 which is approximately 0.8% of 77,434 GWh, the total power generated by
photovoltaics in 2019.7
Land 8se
To conduct agrivoltaics, a part of farmland area where mounting foundation is constructed must be approved to be
converted to “non-agricultural use” by local Agricultural Commission at municipality level (Table 2). Currently, there
are 1,703 Agricultural Commissions in 1,724 municipalities.8 Solar parks are constructed mainly in the second and
the third class farmland because of ease in obtaining land conversion approval, while agrivoltaics takes place in all
classes since it is meant for agriculture.
There are two grave concerns in the Japanese agriculture: aging population of farmers and increase in abandoned
farmland. Agrivoltaics is expected to contribute to solve the latter issue. The acreage of the abandoned farmland is
423,000 ha from the latest national census in 2015, which is 9.4% of the total farmland area of 4,496,000 ha (Table
3). The conversion of farmland to photovoltaic use started from 2011 after the introduction of feed-in tariff (FIT)
scheme. The cumulative farmland area converted so far to solar parks and agrivoltaics is 9,964 ha and 560 ha,
respectively (Table 3).
Though there is no area-based statistics, 31% of approved cases of farmland conversion to agrivoltaics was in
devastated farmland by 2018 (Table 2). This ratio was down to 15% in 2020 but the number of cases is increasing
except a slight decline in the second and the third class farmland, from 21 to 17 cases and from 7 to 5 cases,
respectively. This decline is most likely attributed to difficulty to continue farming in the low grade, devastated
farmland, or conversion to more profitable land use due to the vicinity of urban area, which may include solar parks.
Some argues that the conversion of farmland, including devastated farmland, to agrivoltaics will accelerate while
the conversion to solar parks will be declining, because convertible farmland to solar parks are saturating.9 There is
030002-2
no statistical evidence to support the “saturation” but it is a likely scenario particularly considering policy guidance in
the renewed FIT scheme to gear towards this change that is discussed later in Policy Framework.
TABLE 2. Land conversion policy and approved farmlands for agrivoltaics by farmland classesa
Farmland
classification
Farming conditions, urbanization situation Approval
policy
Survey
year
Total Devastated farmland
(
cases
)
%
(
cases
)
% to total
Farmland
within the
agricultural
district
Agricultural land designated as an agricultural
land area in the Agricultural Promotion Area
Development Plan
Not permitted in
principle
(There are
exceptions
based on the
businesses
subject to the
Agricultural
Land Law and
Land
Acquisition
Law)
2018 537 71.1 161 30.0
2020 1,425 74.5 205 14.4
First grade
farmland
Farmland with particularly good farming
conditions (Agricultural land, etc. that was the
target of land improvement projects in
urbanization control areas within 8
y
ears
)
2018 3 0.4 0 0.0
2020 12 0.6 0 0.0
First class
farmland
Farmland with good farming conditions (A
group of farmlands with a scale of 10 ha or more
/ farmland targeted for land improvement
p
ro
j
ects, etc.
)
2018 119 15.8 45 37.8
2020 333 17.4 59 17.7
Second class
farmland
Farmland that is expected to be in the city
(Small group farmland with low productivity,
such as a railway station within 500 m)
Permitted on
condition
(Cannot be
located in other
areas around
)
2018 79 10.5 21 26.6
2020 110 5.8 17 15.5
Third class
farmland
Farmland in urban areas or areas with a marked
tendency to urbanize (Railway station is within
300 m, etc.
)
Permitted in
principle
2018 17 2.3 7 41.2
2020 33 1.7 5 15.2
Total 2018 755 100.0 234 31.0
2020 1,913 100.0 286 15.0
a Combined reference 4, 10 and 14.
TABLE 3. Total, devastated, abandoned, and converted farmland to photovoltaics in Japana
Farmland Devastated farmland Abandoned farmland Converted farmland
JPY (ha) Restorable
(ha)
Non-restorable
(ha)
Total
(ha)
Ratio to farmland
(%)
Total
(ha)
Ratio to farmland
(%)
to solar parks
(ha)
to agrivoltaics
(ha)
1961 6,086,000
1975 5,572,000 131,000 2.4%
1980 5,461,000 123,000 2.3%
1985 5,379,000 135,000 2.5%
1990 5,243,000 217,000 4.1%
1995 5,038,000 244,000 4.8%
2000 4,830,000 343,000 7.1%
2005 4,692,000 386,000 8.2%
2008 4,628,000 149,000 135,000 284,000 6.1%
2009 4,609,000 151,000 137,000 287,000 6.2%
2010 4,593,000 148,000 144,000 292,000 6.4% 396,000 8.6%
2011 4,561,000 248,000 130,000 278,000 6.1%
0.7
2012 4,549,000 147,000 125,000 272,000 6.0% 264.6
2013 4,537,000 138,000 135,000 273,000 6.0% 1,616.0 19.4
2014 4,518,000 132,000 144,000 276,000 6.1% 3,883.6 79.9
2015 4,496,000 124,000 160,000 284,000 6.3% 423,000 9.4% 5,464.4 151.8
2016 4,471,000 98,000 183,000 281,000 6.3%
7,019.3 331.0
2017 4,444,000 92,000 190,000 283,000 6.4% 8,268.8 413.1
2018 4,420,000 92,000 188,000 280,000 6.3% 9,964.3 560.0
a Compiled from reference 11, 12 and 13. Figures are rounded to the nearest thousand except those in the converted farmland.
Grown Crops
Over 120 kinds of crops have been grown in the Japanese agrivoltaic farms.15 Top ten popular crops includes
mioga ginger (65 farms), Sakaki or Japanese cleyera (41 farms), paddy rice (35 farms), shiitake mushroom (31 farms),
and blueberry (20 farms), fuki or butterbur (18 farms), tea (15 farms), green onions (14 farms), pasture grass (13 farms),
and pumpkin (13 farms) (Table 4). Paddy rice is ranked at the third as a popular crop in agrivoltaics not necessarily
because it agronomically fits to agrivoltaics but mainly because it is a major crop grown in Japan. It is widely debated
whether cultivation of some crops like Janapnese cleyera should be expanded just because it is shade-tolerant fitted to
agrivoltaics. This plant is used in a Shinto ritual so that it has a fixed, small market. It is rational to introduce
agrivoltaics to the existing Janapnese cleyera farms, however, it is worried that new introduction or expansion,
particularly if it is large scale, may disrupt the existing market. The same debate applies to similar crops in religious
plants, ornamental plants, or mushrooms groups.
The cultivated crops in agrivoltaics is categorized by crop classification by MAFF (Table 5). Future research may
want to access these groups for economic, agronomical, environmental, and social feasibility and impact. Overall crop
030002-3
conversion rate is relatively high at 69%. Notable difference in the crop conversion rate is observed among different
crop groups: (1) over 80% (vegetables, ornamental plants), (2) 50 to 70% (mushroom, flowers, fruit tree), (3) 30 to
50% (tea, pasture), and (4) at 10% level (land use crops) (Table 5). Unique crops (89% crop conversion rate) and
Mioga (86% crop conversion rate) are sub-categorized since MAFF is concerned with its impact to a small, inflexible
existing market as mentioned above. Some of the crop change is likely restricted within variety or cultivar level. Tea
(43% crop conversion rate) is likely in this category, which requires 4 to 5 years of leading time after planting before
the first harvest. Tea farmers may want to utilize an opportunity of installing agrivoltaics to replant a high-yielding or
high value-added tea cultivar (this will be further elaborated later in a case study). The crop conversion rate of land
use crops or cereals is distinctively low at 15%. They are often a major income source for farmers that is unlikely to
be switched to other crops. Besides, in case of paddy rice, it requires certain period to prepare an ideal flooded field
conditions and soil.
TABLE 4. Crops grown in agrivoltaic farms in Japana
Number
of cases Common name (Scientific name) [number of cases]
>10 mioga ginger (Zingiber mioga Rosc.) [65], Japanese cleyera (Cleyera japonica) [41], paddy rice (Oryza sativa) [35], shiitake
mushroom (Lentinula edodes) [31], blueberry (Cyanococcus spp.) [20], fuki / butterbur (Petasites japonicus (Siebold et Zucc.)
Maxim.) [18], tea (Camellia sinensis (L.) O. Kuntze) [15], green onions (Allium fistulosum L.) [14], pasture g rass [13],
p
um
p
kin
(
Cucurbita maxima
)
[
13
]
, sweet
p
otato
(
I
p
omoea batatas
)
[
11
]
,
p
ersimmon
(
Dios
py
ros kaki
)
[
11
]
9 oran
g
e
(
Citrus unshiu
)
8 so
y
bean
(
Gl
y
cine max
)
,
p
otato
(
Solanum tuberosum L.
)
, taro
(
Colocasia esculenta
(
L.
)
Schott
)
7 asparagus (Asparagus officinalis L.), wood ear mushroom (Auricularia auricula-judae), lettuce (Lactuca sativa), peanut
(
Arachis h
yp
o
g
aeaii
)
6 cabba
g
e
(
Brassica oleracea L. var. ca
p
itata.
)
, senr
y
u
(
Sarcandra
g
labra
)
5 bracken fern (Pteridium aquilinum (L.) Kuhn.), Japanese horseradish (Eutrema japonicum (Miq.) Koidz.), carrot (Daucus
carota subsp. sativus), ashitaba (Angelica keiskei (Miq.) Koidz.), onion (Allium cepa), radish (Raphanus sativus var. hortensis),
dwarf mondo grass (Ophiopogon japonicus 'Tamaryu'), tomato (Solanum lycopersicum), Chinese cabbage (Brassica rapa var.
p
ekinensis
)
, Ja
p
anese star anise
(
Illicium reli
g
iosum Siebold & Zucc.
)
,
g
arlic
(
Allium sativum
)
4 Gra
p
e
(
Vitis s
pp
.
)
, Ja
p
anese chestnut
(
Setaria italica
)
,
y
oun
g
so
y
bean
(
Gl
y
cine max
)
, barroom
p
lant
(
As
p
idistra elatior
)
3 buckwheat (Fagopyrum esculentum Moench), wheat (Triticum aestivum), komatsuna (Brassica rapa var. perviridis), citron
(Citrus junos), spinach (Spinacia oleracea), Chinese chives (Allium tuberosum. Rottler ex Spreng.), chameleon plant
(
Houttu
y
nia cordata
)
, lemon
(
Citrus limon
)
, kiwifruit
(
Actinidia chinensis
)
2 fig (Ficus carica), mini tomato (Lycopersicum esculentum), potato (Solanum tuberosum L.), ginger (Zingiber officinale), udo
(Aralia cordata), broccoli (Brassica oleracea var. italica), Japanese pepper tree (Zanthoxylum piperitum), shiso (Japanese
basil) (Perilla frutescens var. crispa), cucumber (Cucumis sativus L.), dekopon (Citrus unshiu x reticulata Siranui), garden peas
(
Pisum sativum L.
)
, sesame
(
Sesamum indicum
)
, red clover
(
Tri
f
olium
p
ratense L.
)
1 hascup (Lonicera caerulea var. emphyllocalyxi), maitake (hen-of-the-woods) (Grifola frondosa), Jerusalem artichoke
(Herianthus tuberosus L.), garland chrysanthemum (Chrysanthemum coronarium L.), water convolvulus (Ipomoea aquatica
Forsk.), leaf lettuce (Lactuca sativa var. crispa), Blackberry (Rubus fruticosus), sudachi (Citrus sudachi), ostrich fern
(Matteuccia struthiopteris), Hydrangea (Hydrangea macrophylla), pak choi (Brassica rapa var. chinensis), Christmas rose
(Helleborus spp.), turf grass (Zoysia spp.), bulb, black squirrel (Ilex rotunda), yacon (Smallanthus sonchifolius), rakkyo
(Allium chinense G.Don), di chondra (Dichondra spp.), holly nanten (Mahonia japonica (Thunb.) DC.), rape (Brassica
campestris L.), trefoil (Cryptotaenia japonica), fukinoto (Petasites japonicus (Siebold et Zucc.) Maxim.), cauliflower (Brassica
oleracea var. botrytis), mugwort (Artemisia spp.), apple (Malus pumila var. domestica), high moss (Hypnum plumaeforme.
Wilson.), currant (Ribes spp.), flowers, maize (Zea mays), kiboshi (Hosta spp.), strawberry (Fragaria ×ananassaDuchesne ex
Rozier), shimeji (Hypsizygus marmoreus), moss, herbs, eggplant (Solanum melongena), watermelon (Citrullus lanatus), June
berry (Amelanchier canadensis), prickly pear (Anredera cordifolia), Japanese apricot (Prunus mume), jabara (Citrus jabara
hort. ex Y. Tanaka), moss phlox (Phlox subulate), coralberry (Ardisia crenata), plantain (Plantago asiatica), shibuki (Myrica
rubra), turnip (Brassica rapa L.), okra (Abelmoschus esculentus), senna tea (Senna obtusifolia), kiyomi tangor (Citrus unshiu ×
sinensis), cherry (Prunus spp.), giant elephant ear (Colocasia gigantea), Chinese milk vetch (Astragalus sinicus L.), fodder,
hanashiba (Illicium religiosum), mulberry (Morus spp.), hyuganatsu (Citrus tamurana), kumquat / cumquat (Citrus japonica /
Fortunella japonica), Solomon’s seal (Polygonatum spp.), dracaena (Dracaena spp.), coffee (Coffea spp.), bitter gourd
(
Momordica charantia
)
, turmeric
(
Curcuma lon
g
a
)
a Modified reference 15.
TABLE 5. Crops grown in agrivoltaics by classificationa
Classification Major crops Number
of cases
Ratio
(%)
Number of
crop change
casesb
Crop
conversion
rate
(
%
)
Land use crops rice (Oryza sativa), wheat (Triticum aestivum), soybean (Glycine
max
)
, buckwheat
(
Fa
g
o
py
rum esculentum Moench.
)
173 9 26 15%
Vegetables Vegetables: komatsuna (Brassica rapa var. perviridis), Chinese
cabbage (Brassica rapa var. pekinensis), green onions (Allium
f
istulosum L.
)
,
p
um
p
kin
(
Cucurbita maxima
)
, etc.; Root cro
p
s
713 37 592 83%
Unique crops mioga ginger (Zingiber mioga Rosc.), fuki / butterbur (Petasites
japonicus (Siebold et Zucc.) Maxim.), udo (Aralia cordata),
ashitaba (Angelica keiskei (Miq.) Koidz.), bracken fern (Pteridium
aquilinum (L.) Kuhn.), chameleon plant (Houttuynia cordata), red
clover
(
Tri
f
olium
p
ratense L.
)
403 21 358 89%
mio
g
a mio
g
a
g
in
g
er
(
Zin
g
iber mio
g
a Rosc.
)
209 11 180 86%
030002-4
Classification Major crops Number
of cases
Ratio
(%)
Number of
crop change
casesb
Crop
conversion
rate
(
%
)
Fruit tree citrus (Citrus spp.), blueberry (Cyanococcus spp.), persimmon
(
Dios
py
ros kaki
)
,
g
ra
p
e
(
Vitis s
pp
.
)
211 11 122 58%
Flowers lily (Lilium spp.), pansy (Viola × wittrockiana) 12 1 8 67%
Ornamental
plants
Japanese cleyera (Cleyera japonica), Japanese star anise (Illicium
religiosum Siebold & Zucc.), senryo (Sarcandra glabra), dwarf
mondo
g
rass
(
O
p
hio
p
o
g
on
j
a
p
onicus 'Tamar
y
u'
)
, etc.
553 29 447 81%
Others - 252 13 129 51%
Pasture Italian ryegrass (Lolium multiflorum), sorghum (Sorghum
bicolor
)
, Chinese milk vetch
(
Colocasia
g
i
g
antea
)
68 4 24 35%
Mushrooms shiitake mushroom (Lentinula edodes), wood ear mushroom
(
Auricularia auricula-
j
udae
)
98 5 68 69%
Tea tea (Camellia sinensis (L.) O. Kuntze) 65 3 28 43%
TOTAL 1,914 100 1,324 69%
a Modified reference 14.
b The number of cases where cultivated crops were changed upon introduction of agrivoltaics.
Shading Rate
Shade tolerance of a crop or shading rate is one of the major factors to determine agrivoltaic system.
According to MAFF’s report in 2018, 4 the shading rate in agrivoltaic farms in Japan is widely distributed from
less than 10% to 100%, with its median in 30 to 40% range (Figure 1). Approximately 20% of agrivoltaics has less
than 30% of shading rate, 40% has less than 40% shading rate, 20% has more than 70% shading rate, and 10% has
more than 80% shading rate. Unfortunately, this survey lacks associated crops to a particular shading rate.
FIGURE 1. Shading rate distribution in agrivoltaic farms in Japan. Plotted from “Current status of agrivoltaic facilities.”4 n=732
out of 755 agrivoltaic farms granted the land conversion permit, for which a defined shading rate, (PV panel area/filed area), is
known. Some 240 farms (32%) has more than 1,000 m2 of cropping field.
FIGURE 2. Average shading rate by crop classification. Plotted from reference 15. n=1,174 out of 1,465 (80.1% response rate).
100% shading rate for shiitake mushroom (Lentinula edodes), ginseng (Panax ginseng), and bracken fern (Pteridium aquilinum
(L.) Kuhn.) and some shiitake mushroom farm with photovoltaic panel installed at 60 cm above ground reported.
Actually used shading rate in agrivoltaic systems were surveyed by another study (Figure 2).
Average shading rate ranges from 31.1% for rice to 100% for mushroom, ginseng, and bracken fern. The choice
of the shading rate is often made using light saturation point as a benchmark, which was suggested by Nagashima.1, 2
0-10 20-10 20-30 30-40 40-50 50-60 60-70 70-80 80-90 90-100
No. of cases 5 31 108 176 110 91 76 61 25 49
Ratio 0.7% 4% 15% 24% 15% 12% 10% 8% 3% 7%
0
50
100
150
200
No. of cases
35.1
35.9
36.7
38.7
41
41
41.3
42.8
43.1 49.6 60.2 65.9 73.4
0 1020304050607080
Cereal
Beans
Root crop
Fruit tree
Gourds / Eggplants
Mioga
Mushroom
Average shading rate (%)
030002-5
However, choice of the shading rate comes first rather than crops in many cases, since farmers or investors to
agrivoltaics seek a way to maximize their income from electricity sale under FIT scheme, which is much higher than
their agricultural income, then choose a suitable crop for that shading rate. This explains why the crop conversion rate
is particularly high for mostly shade tolerant crops in the unique crops and the ornamental plants category (Table 5)
and they are ranked in the upper tier of popular agrivoltaic crops (Table 4).
POLICY FRAMEWORK
A number of governmental policies have been instrumental in promoting agrivoltaics in Japan (Table 6).
In 2011, FIT scheme was finally institutionalized in Japan, which final legislation process coincided with the Great
East Japan Earthquake in March 2011 that caused Fukushima Daiichi Nuclear Power Plant disaster. FIT was originally
proposed in 2000 by bipartisan parties but Japan acquired Renewables Portfolio Standard (RPS) system instead in
2003. RPS was marginally effective only doubling the renewable energy supply under RSP scheme from 4,000 GWh
in 2003 to 8,000 GWh in 2009,17 which did not result in overall increase in the national renewable energy supply
during the same period, that was 117,000 GWh to 105,000 GWh.7 Japan had to wait to see significant increase in
renewable energy supply until the enforcement of FIT scheme in 2012. It increased by 76% from 2012 to 2019, from
110,000 GWh to 195,000 GWh, respectively.7 Photovoltaics has been a key driving force in this increase to see ten
times increase in this period from 7,600 GWh to 77,000 GWh.
On March 31, 2013, official directive was issued by the director of Rural Development Bureau, MAFF to the head
of Regional Agricultural Administration Offices nationwide stipulating the procedure and conditions to permit
farmland conversion for agrivoltaic use (Table 6), which applies to “Farmland within the agricultural district,” “First
grade farmland,” and “First class farmland.” Once it is approved, the applicant can perform agrivoltaics in the applied
lot of farmland for maximum of 3 years. The application is to be filed through local Agricultural Commission. The
major conditions are as follows: (1) mounting structure is only temporary and easily removed, (2) elected photovoltaic
panel should not hinder growth of crops so as to secure enough sunlight penetration for plant growth and enough at
least 2 m of above ground height of the panel for agricultural machinery operation, (3) the installment should not
hinder agricultural practice in surrounding areas including agricultural drainage system nor adversely affect the
implementation of “Agriculture Promotion Area Maintenance Plan,” and (4) annual yield must be reported and yield
reduction should not exceed 20% of the one before agrivoltaic installation.
On May 15, 2018, a revised directive was issued (Table 6), which included a major policy update: the permit is to
be granted for 10 years, instead of 3 years, if (1) a farmer can demonstrate his competence in agricultural practices
and management, (2) agrivoltaics takes place in “Devastated farmland,” or (3) agrivoltaics takes place in “Second
class farmland” or “Third class farmland.” Applications which do not apply to any of these conditions are treated as
before with the maximum permit period of 3 years.
On June 12, 2020, the second amendment of FIT Law was promulgated which will be enforced on April 1, 2022
(Table 10). It contains several key changes in policy including (1) introduction of feed-in premium (FIP) scheme, (2)
requirement for a large-scale solar parks to make an external reserve for costs for dismantling photovoltaic equipment,
and (3) requirement for a small-scale (10 to 50 kW) photovoltaic facilities to fulfill “regional use requirements” to
obtain a FIT certificate.
The last requirement applies to most agrivoltaic farms and the law provides added preferential treatment to
agrivoltaics to encourage its further development. There are three “regional use requirements:” (1) self-consumption
rate must be at least 30%, (2) there must be a way to confirm the actual self-consumption, and (3) generated electricity
must be usable during disaster (a PCS or inverter with at least 10 kW operational capacity should be self-operatable
without external power supply to provide at least 1.5 kW output during disaster). For agrivoltaics, however, the first
requirement of compulsory self-consumption is waived if all the following three conditions are fulfilled: (1) its
capacity is within 10 to 50 kW, (2) it already obtained a farmland conversion permit for 10 years, and (3) it is
agrivoltaics.
TABLE 6. Key policy guidance to stimulate development of agrivoltaic farms in Japan
Time Law / Policy
August 2011
(Enforced in
July 2012)
Japanese government introduced a renewable energy feed-in tariff (FIT) scheme, which made it mandatory for electric
power companies to buy electricity from renewable sources at fixed prices for 10 to 20 years (“Act on Special Measures
Concerning Procurement of Electricity from Renewable Energy Sources by Electricity Utilities”).
March 2013 Temporary conversion of farmland for agrivoltaic use for the maximum of 3 years is officially permitted for the first time
by MAFF Notification No. 24 Noushin Article 2657.17
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Time Law / Policy
Nov. 2014 “Act on the Promotion of Renewable Energy Electric Power Generation Harmonized with Sound Development of
Agriculture, Forestry and Fisheries” is enforced.18
April 2017 “Act on Special Measures Concerning Procurement of Electricity from Renewable Energy Sources by Electricity Utilities
(FIT Law)” was revised, enacted in March 2016 and enforced on April 1, 2017.
May 2018 The temporary conversion period will be extended to ten years from three years, if a farmer proves his competence in
farming or uses devastated farmland (MAFF Notification No. 30 Noushin Article 78).19
June 2019 Cabinet council recognized agrivoltaics as means to build a powerful agriculture structure and to develop human resources
despite a declining population, stipulating “Farming-photovoltaics, where photovoltaics equipment is installed above
farmland, will be expanded nationwide.” in “Follow-up on the Growth Strategy.”20
June 2020 Enacted revised FIT Law renamed as “Act on Special Measures Concerning Promotion of Use of Renewable Energy
Electricity,” which will be enforced on April 1, 2022.21
FURTHER POTENTIAL AND BEST PRACTICE
Revitalizing the use of abandoned farmland is a prime interest in the agricultural policy in Japan.
The total area of abandoned farmland in Japan reported in the latest agricultural census is 423,064 ha as of 2015
(Table 3).22 Converting all this area to agrivoltaic farms, we can potentially produce 280 GW of electricity. The
maximum potential of agrivoltaic farms to be established in Kanto Region (8 prefectures) alone is estimated at 65.1
GW (69,188 GWh yearí1)23 or more modestly 15.2 to 32.6 GW,24 both of which estimates use a standard unit capacity
of agrivoltaics, 0.05 kWh mí2.
Tea is proven to be one of the most suitable crops for agrivoltaics. It is the 7th popular agrivoltaic crop cultivated
in at least 65 farms (Table 4). Agrivoltaic tea farming provides numerous solutions to the problems that farmers faced
in the conventional tea farming, while offering added economic and environmental values. A case study from an
agrivoltaic tea farm in Shizuoka Prefecture gives us insight suggesting the future direction of agrivoltaics.
Almost one tea cultivar, Yabukita (Chanorin no. 6) is dominant in mecca of the Japanese tea farming, Shizuoka
prefecture, but some tea farmers converted it to more profitable, high value-added tea cultivar like Okumidori
(Chanorin no. 32) upon electing agrivoltaics as we see in Ryutsu Service Co., Ltd. case.25
Matcha is the one of the highest quality Japanese green tea, which is made by griding tencha into powder.
Okumidori is a suitable cultivar to produce tencha. Ballpark figure of wholesale price of matcha made of Okumidori
is ten times more than that of ordinally Yabukita tea. Producing tencha, however, requires special cares of tea tree,
where agrivoltaics can play a significant role.26 Only fresh young shoots are picked and used for tencha. To produce
tender, mild, sweet taste, tea plants must be grown under the darkness at 90% shading rate from the 1 to 1.5 leaf stage
for about 20 to 30 days during the growing period to suppress catechin formation, which causes bitter taste. The
cheapest way to achieve this is to cover the tea plant manually with the dark shading net, i.e., direct netting, but the
net readily damages young shoots because it directly contacts with tea plant and it also create a hot and humid
environment, which is an ideal condition for plant disease propagation. A netting frame can be constructed to
overcome these drawbacks, but it costs you 15 to 20 million Japanese yen haí1. Introducing agrivoltaics can solve all
these problems. Mounting frame of agrivoltaics can substitute the netting frame. Photovoltaic panels also provide a
milder growing conditions to the tea plant grown underneath, mitigating harsh direct sunlight during the hottest season
and preventing frost formation during the coldest season, which negate the cost of frost protection fan normally used
in the conventional tea farming.
It is said that 97% of tea tree in Shizuoka prefecture is Yabukita and they are around 50 years old, which should
be replanted to maintain its quality and productivity. However, many farmers are reluctant to do so because of its cost
and aging farming population. You need to wait 4 to 5 years after planting tea tree to see the first harvest and income
for which income from electricity sale of agrivoltaics can compensate.
Agrivoltaic tea farming also had a positive impact on marketing. Matcha itself is already high value-added product
but agrivoltaics enhanced the value further. It started attracting environmentally conscious international buyers from
overseas. Organic, renewable energy, healthiness, all sounds very attractive to the buyers. Ryutsu Service Co., Ltd.26
now has constant sales to buyers in New York, London, and other international destinations.
In sum, agrivoltaic tea farming has a potential to revitalize aging tea farming industry in Shizuoka prefecture,
which may enlighten other farming systems elsewhere.
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ACKNOWLEDGMENTS
The completion of this review could not have been possible without valuable studies and surveys to collect and
compile primary data and information by researchers and governmental institutions whose name may not all be
enumerated. Their contributions are deeply appreciated and gratefully acknowledged.
We would like to express our deep appreciation and indebtedness particularly to the followings:
Ms Ayako Kikuchi and the Ministry of Agriculture, Forestry and Fisheries for their advice and provision of
agrivoltaic survey results. Dr. Hideshi Kurasaka and Dr. Joji Magami for their comprehensive survey on agrivoltaic
farms in Japan. Mr. Yoshiaki Hattori for pioneering an innovative approach to tea agrivoltaics and its detailed
elaboration to us. Dr. Hironao Matsubara, our colleague, for decades of his work to compile renewable energy statics
in Japan and provision of raw data.
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