Japanese Farmers Producing Crops and Solar Energy Simultaneously
Revitalizing the farming sector for the next-generation
and could provide more than enough electricity for the entire countryDr Mae-Wan Ho
Restriction to solar PV installation on farmlands removed
Farmers in Japan are taking advantage of new opportunities
to generate electricity while growing crops. In April 2013, the Ministry of Agriculture,
Forestry and Fisheries (MAFF) approved the installation of solar PV system on
crop-producing farms, which was previously prohibited under the Agricultural
Land Act, regardless of whether the land is productive or idle .
The practice of food and energy double-generation,
known as “solar sharing” in Japan, was originally developed by Akira Nagashima
in 2004. Nagashima, a retired agricultural machinery engineer, studied biology
and learned of the light saturation point at which increase in the level of
sunlight does not cause any further increase in the rate of photosynthesis. (Actually,
only a small fraction of the incident sunlight is needed for plants to reach
maximum rate of photosynthesis; too much light can be damaging, and plants have
evolved mechanisms to protect themselves from being ‘sunburnt’; see  Harvesting Energy
from Sunlight with Artificial Photosynthesis, SiS 43).
Nagashima came up with the idea of combining
PV with farming. He devised and originally patented a special structure like a
garden pergola, which was tested in fields with different crops and shading
rates. The structures are made of pipes and rows of PV panels mounted above
ground, and arranged at certain intervals to allow enough sunlight for
photosynthesis. There is no concrete footing so the structures can be easily
dismantled; the system is designed to allow adequate sunlight for crops and
space for agricultural machinery to be used, as stipulated by MAFF guidelines.
According to Nagashima, the MAFF guidelines
are to ensure that farmers remain farmers, and not to fully convert productive
farmland into solar facilities. Based on his tests in the Chiba Prefecture, he
recommends about 32 % shading rate. Farmers are required to report their annual
crop cultivation, and if the amount cultivated on the solar-shared farmland
falls below 80 %, they will be required to dismantle the PV system.
Makoto Takazawa, owner of the 34.4 kW Kazusatsurumai Solar
Sharing Project in Chiba Prefecture said solar sharing can re-activate the
declining farming sector. Farmers in Japan are suffering reduced farm revenues
and lack of successors. Many small farmers are forced to take on a second job
to make ends meet. Takazawa installed 348 PV panels on a small 750 square metre
farm, mounted on pipes 3 metres from the ground. Under the solar panels,
Takasawa’s father has cultivated peanuts, yams, eggplants, cucumber, tomatoes
and taros, and cabbages during the winter. The vegetables are sold at a nearby
street market and consumed by his neighbours.
The PV system produces 35 000 kWh a year and
cost Takazawa about 12.6 m yen ($126 000) to install. He secured the first
available FIT (feed-in-tariff) rate of 42 yen/kWh for 20 years, earning 1.6
million yen (~$16 ooo) annually, while making only 100 000 yen (~$1 000) from
farming. “I hope this will attract young people to come back to the
countryside” Takazawa said.
Solar sharing at Chiba on Takazawa’s farm (renewable
The practice has since spread to
other prefectures such as Aichi, Mie and Ibaraki .
In Aichi Prefecture, Tsuboi has designed and
self-installed a 50 kW system over the growing citrus trees . About 600 PV
panels are installed in the 7.7 acres farm mounted on 5 metres high steel
pipes. The citrus grown is a hybrid of mandarin and orange. Tsuboi has a second
job; this year, he expects the PV system to bring 2.5 million yen (~$25 000) in
Is the structure stable and durable?
Nagashima said that his systems even withstood strong winds and earthquakes
during the Fukushima tsunami disaster of 2011. The systems are lightweight and
the panels spaced out, allowing air to flow through, thereby reducing wind
load. He suggested solar-shared farming for ranches in the United States. The
solar panels would be especially suitable over grass pasture to provide shade
for cattle or sheep, and also reduce irrigation as more moisture is retained.
Solar-shared faming may be appropriate for
other regions such in Africa and Latin America, and the Middle East, where
incident sunlight is intense, and water scarce.
Helping Fukushima farmers through the nuclear crisis
Farmers in Fukushima Prefectureare also turning to
solar- sharing. They are hoping to sell the power to help cover the losses from
the nuclear crisis at Tokyo Electric Power Company’s Daiichi nuclear power
plant. Solar panels are set up on the farmland, and farmers can use the money
from the sale of the electricity generated to improve the farmland or to cover
losses in come caused by the fear of radiation .
In Minami-Soma, the prefectural government
has begun a model project. A 2 000 square metre farmland in the city’s Odaka
district is designated for solar sharing. It is a “zone being prepared for
residents’ return” where the level of radiation exposure is 20 millsieverts or
less a year. A total of 500 solar panels have been installed 1.9 metres above
ground. Under the panels, eggplants, chili pepper and other produce are grown
on an sexperimental basis.
Solar sharing in Fukushima
Farmer Ichiro Hirata, 62, who owns the land
said that his crops will not sell for the time being due to “groundless rumours
of contamination.” But until prices recover, he can cover the loss by selling
An increasing number of Fukushima
farmers are taking up the scheme. In addition to the model project in
Minami-soma, Eko Ene Minami-soma Kenkyu Kiko, an incorporated foundation, plans
a solar-sharing project on about 600 square metres of farmland, and expects
about 1 million yen of annual revenue from the sale of electricity generated.
The town government of Aizubange in Fukushima
Prefecture is also considering introducing the scheme as are some farmers in
Sendai of Iwate Prefecture; an official in the government’s agriculture
promotion division has received enquiries from farmers and from local agricultural
More than enough farmland to provide all of Japan’s
Japan requires about 2.5 million acres of land to supply the
entire country’s electricity with PV . Under the solar-share scheme, it will
take about 7 million acres of farmland to supply the same amount of
electricity. Japan currently has more than 11.3 million acres of available
Solar sharing could well be a readily
available alternative to artificial photosynthesis  in harvesting sunlight,
as batteries for energy storage improve and come down in price  (Renewable
Ousting Fossil Energy, SiS 60).
Before the industrial revolution, farmers provided
both crops and energy in the form of firewood and charcoal to society,
Nagashima said , solar-share farming will do the same again and revitalize
the farming sector.
Todd Millions Comment left 29th October 2013 08:08:49 I would be interested in any guttered measurements of dew condensing from these arrays,at given low tempture points and humidity levels.The 35% shading is similar to test sections done in US in 1970's at similar latitudes.The arrays shown don't seem to me suitable for cattle-fighting and rubbing.Testing with goats,sheep,llamas-alpacas ect may be a good first step.Do range(Berkshire)pigs-dig enough to cause concern?
Abhi Roy Comment left 2nd December 2013 10:10:25 Solar power is a good resource in renewable energy area. Especially for farmers, solar panel and solar module mounting structure product is a great aid for them.
kishor Comment left 16th October 2015 07:07:26 Can the facility of both farming and solar farming in india?