Japan's solar-sharing tech faces crossroads as MAFF tightens rules ahead of 2027

“Solar sharing,” a technology that enables simultaneous power generation and farming under solar panels, is now at a crossroads. This innovation, born in Japan, faces a critical juncture. Under a new regulatory framework set to take effect in April 2027, stricter rules are expected, prompting concerns among industry stakeholders that the measures could hinder the technology’s widespread adoption. [Photo] Scenes from solar sharing sites, including the installation of vertical solar panels and cattle grazing. We spoke with Kei Kondo, co-representative director of the Solar Sharing Promotion Alliance (a general incorporated association) and president of Nihonmatsu Agricultural Solar, who operates a farm in Fukushima Prefecture. (By Kohei Koizumi, writer and editor)

“Shading rate of 30% or less”: A gap between the standard and on-the-ground realities

On October 9, a new regulatory framework concerning agricultural solar power generation was promulgated. Amendments to the ministerial ordinances and basic policies related to the Renewable Energy Act for Agricultural, Forestry, and Fishing Communities (hereinafter referred to as the Agricultural, Forestry, and Fishing Communities Renewable Energy Act) have effectively strengthened regulations on agricultural solar power generation.

Prior to this, the Solar Sharing Promotion Alliance, an industry association, had expressed concerns about the strengthened regulations through submissions to the "Study Group on Desirable Agricultural Solar Power Generation" established by the Ministry of Agriculture, Forestry and Fisheries, as well as through public comment processes. Keiko Kondo, the co-representative director of the alliance, stated:

"Originally, the review should have focused on strategies to increase 'desirable agricultural solar power generation' while reducing the number of inappropriate operators. Many farmers practicing solar sharing had called for the simplification of overly complex review procedures. Instead, the barriers to entry have been raised. We intend to continue advocating for improvements to the system."

One of the issues highlighted by the Promotion Alliance in the new framework is the newly introduced criterion that the shading rate of solar panels installed on farmland must be less than 30%.

Generally, a lower shading rate allows more sunlight to reach the crops, and in many cases, this correlates with better crop growth. However, looking at the track record of agricultural solar power generation projects nationwide, there are numerous instances where crops have grown properly despite high shading rates. For example, potatoes have been cultivated with a shading rate of 68.5%, and soybeans with a rate of 33%. Additionally, some crops, such as tencha (powdered green tea) and coffee, inherently require high shading rates.

"No clear justification has been provided for why 30% was chosen as the threshold. In fact, five out of the seven success cases of agricultural solar power generation featured on the Ministry of Agriculture, Forestry and Fisheries' website have shading rates of 30% or higher. The targets for enforcement should be the few operators who merely sell electricity while neglecting farming. It is nonsensical to set an extremely high threshold that excludes even those seriously engaged in agriculture."

However, exceptions to this standard have been established. Under the "Basic Plan" that municipalities are required to formulate based on the Agricultural, Forestry, and Fishing Communities Renewable Energy Act, it is stated that "special measures can be established" in accordance with local policies and characteristics.

While shading rates above 30% should theoretically be possible, municipalities must provide scientific evidence, such as "multi-year trial cultivation by public institutions," to establish such "special measures." Kondo questions whether this practice will actually expand in the future, even if it is permissible under the rules.

"For municipalities that are positive about agricultural solar power generation, this could be a positive factor. However, I am concerned that many municipalities lack sufficient manpower and will be unable to create the 'Basic Plan.' A municipal official I spoke with expressed reluctance about the new responsibilities imposed on the local government. It is likely that some municipalities will deliberately set high barriers to block new entrants."