1st Project Finance for Agricultural Mega Solar Plant Revitalizes Idle Farmland (1)
3 former prime ministers gather at mecca of solar sharing
Kaihata District in Sosa City, Chiba Prefecture, is becoming one of Japan's major concentrations of solar sharing projects (agricultural solar power generation plants). The gently sloping district is covered with a vast range of fields. However, about a quarter of the fields are abandoned, partially due to the lack of successors. Some of the fields are covered with weeds or illegally dumped waste, which are serious problems.
Soybeans grown under panels
People began to take action to revitalize the wasted land by solar sharing. When I drove through Kaihata District, solar power plants with long and narrow strips of solar panels installed on mounting systems slightly higher than normal, which looked like wisteria trellises, were seen in some places, and crops including soybeans were being grown under the panels.
"Sosa Mega Solar Sharing No. 1 Power Plant," an agricultural mega solar plant, which was completed in April of this year, is one of the largest among the plants in this solar sharing mecca. The power generation facility was constructed on a 3.2ha site consisting of abandoned fields and features 1.2MW of solar panel capacity and 1MW of output to the grid (Fig. 1 & 2).
Completion ceremony attended by three former prime ministers
The farmland on which the mounting systems were built was temporarily converted by utilizing the system to operate solar power generation businesses on farmland. A local agricultural production corporation plans to grow high-value-added organic crops such as soybeans and wheat on the farmland under the panels. The power plant is estimated to generate approximately 1,424MWh of power per year.
The power producer is Sosa Solar Sharing GK, a special purpose company. The SPC was established by Shimin Energy Chiba (Sosa City), which promotes solar sharing in Sosa City and other areas, and is also financed by en (Shibuya-ku, Tokyo) and Chiba Ecological Energy Inc (Chiba City). The plant incorporated solar panels (115W/sheet) manufactured by WWB Corp (Shinagawa-ku, Tokyo) and PV inverters manufactured by SMA Solar Technology AG of Germany.
Experts who promote renewable energy and other people concerned were invited to the completion ceremony on April 3, 2017. Three former prime ministers, Junichiro Koizumi, Naoto Kan and Morihiro Hosokawa, also attended the ceremony. Mr. Koizumi said, "This is a historic step. We can live with solar power alone. I have the feeling that excess power will be generated," expressing his expectation for solar sharing (Fig. 3 & 4).
Shimin Energy Chiba has actually constructed and operated solar sharing-type solar power plants connected to low-voltage transmission lines by raising funds from citizens and others. As for the Sosa Mega Solar Sharing No. 1 Power Plant, which is large in scale, the funds were raised by obtaining project financing from the Johnan Shinkin Bank and underwriting of the bonds by SBI Energy (Minato-ku, Tokyo).
Crops grow with no problem if shading rate is 30%
It was reportedly the first project financing intended for an agricultural mega solar plant in Japan. The project cost was about 300 million yen (approx US$2.68 million). Shimin Energy Chiba invested 20 million yen, the Johnan Shinkin Bank provided 220 million yen through project financing and SBI Energy provided 40 million yen through underwriting of the bonds.
"We have grown crops including soybeans under the panels of the solar sharing power plants that we operate and that are connected to low-voltage transmission lines, and the panels have not affected the crop yields," said Mitsuhiro Higashi, who represents Shimin Energy Chiba. "Crops sometimes grow even better in shade."
Each crop has a "light saturation point," and the amount of photosynthesis does not increase further even if the crops are subjected to sunlight exceeding a certain level. It is known that crops of any kind grow without a problem if the shading rate is 34% or less, Higashi said.
Solar sharing projects under the temporary cropland conversion system are renewed every three years if the decline in the crop yield ratio due to shade generated by panels is within 20%. There are some solar sharing projects whose shading rate is much higher than 30% due to the policy to place priority on the power generation business. The agricultural mega solar plant in Sosa City places priority on farming, and the shading rate is reduced to 30%. Therefore, it is estimated that the plant will easily satisfy the criteria.
When I visited Sosa City in mid-September 2017, soybean seedlings were growing steadily under the panels and the pods were beginning to increase in size (Fig. 5, 6 & 7).
"The soybeans are not at all inferior to soybeans in fields without panels," said Shigeo Tsubaki, who represents Sosa Solar Sharing GK and is also an executive member of Shimin Energy Chiba. "There is no problem in the productivity of the agricultural work either, when compared to general fields."
He explained that tractors can be used with almost no problems if the height of the mounting systems is set at 2.5 to 3m and the distance between supporting posts is set at 4 to 5m.