by Yutaka Shimizu, Senior Executive Researcher

 

(The original article in Japanese was posted in February 2023)

 

Expansion of Solar Sharing

The trend toward decarbonization has been growing globally. Renewable energy sources such as solar power, wind power, geothermal power, small and medium hydropower, and biomass power are promising, diverse, important, and low-carbon domestic energy sources that can contribute to energy security since these sources do not emit greenhouse gases and can be generated within Japan.

Under such global circumstances, there has been a strong focus on activities to share sunlight between the fields of agricultural production and power generation by installing solar power generation equipment on poles to stand in the upper space of cropland (called “agrivoltaics” or “solar sharing”). Solar sharing has been attracting attention not only from the perspective of environment, namely, decarbonization, but also as a method for the agriculture industry, where the workers find it difficult to earn the income stably, to improve the agricultural management through the continuous income produced from the sales of electricity and in-house use of power generated, in addition to the income from the sales of crops.

The key to achieve success in solar sharing is to realize a good balance between continuing agricultural business properly and generating electricity in the upper space of cropland. Installation of power generation facilities needs permission for temporary conversion of cropland to the space for solar power generation according to the Agricultural Land Law. Since how to handle solar power generation was clarified in 2013 with the permission system of cropland conversion, the cumulative number of permitted cases of the conversion for installation of solar sharing systems has reached 3,474, amounting to 872.7 hectares for the eight years until FY2020. According to the survey conducted by the Ministry of Agriculture, Forestry and Fisheries (MAFF), crops grown under solar panels are varied, and 3,313 cases whose cropland still exists at the end of FY2020 include 299 (9%) for grain crops such as rice, wheat, and soybeans; 1,163 (35%) for vegetables such as Chinese cabbages, Japanese mustard spinach (komatsuna), welsh onions, Japanese ginger (myoga), and potatoes; 461 (14%) for fruit trees such as citrus fruits, blueberries, and grapes; 994 (30%) for garden plants such as Japanese cleyera (sakaki), Japanese star anise (shikimi), and bone-knitted lotus (senryo); and 396 (12%) for other crops such as tea, feed crops, and flowers. Vegetables or the like account for the largest share of cultivation (35%), followed by garden plants (30%). Japanese ginger (myoga) has the largest percentage among vegetables or the like. The reason why garden plants are grown increasingly under solar panels is that they can be grown under relatively dark conditions, which enables high light shielding efficiency and therefore increases the number of solar panels used per unit area.

 

Challenges in Solar Sharing

Although solar sharing has been increasingly popular, there are still many challenges in their installation. One of the particular challenges is the difficulty in the use of cropland for the purpose of solar power generation. The views of the agricultural committees established in municipalities nationwide on solar sharing vary in each region. Those regions where solar sharing has already been introduced have favorable views on the conversion. On the other hand, it is sometimes not easy to gain the permission from the agricultural committees in some regions. Another issue is that it is difficult to receive long-term loans for investment in power generation facilities even though the initially established rule for handling of solar power generation under the permission system of conversion can be renewed by reapplying for new permission, because the rule specifies that the period of permission for temporary conversion must not exceed three years. Many other problems have also been pointed out including the fact that at least 80% of the standard yield of the neighboring areas is required when growing crops in the cropland under solar panels.

In response to such concerns from those in the agriculture industry, the system of permission for using cropland as the space for solar power generation was revised in 2018, and the period of permission for temporary conversion extended from three years to ten years in cases where certified farmers or the like operate the farms or in cases where devastated cropland is utilized. Furthermore, another revision was made at the end of FY2020 that the requirement to secure the 80% or more of the standard yield will no longer be imposed, and the permission will be given based on whether or not the cropland is used appropriately and efficiently.

However, even though handling of solar power generation under the permission system of cropland conversion has been revised gradually, it would take around 10 to 15 years to have a return on investment due to the decrease in the price under the system of feed-in tariff (FIT) of solar power generation. Therefore, even if the conditions such as “Certified farmers or the like shall operate the farms.,” “Devastated cropland, including those within areas of agricultural land, shall be utilized.,” and “Type two cropland or type three cropland other than areas of agricultural land shall be used.” are met, and conversion of cropland to the space for solar power generation for 10 years was permitted, it is still not easy to access loans beyond the period. Moreover, as for other above-mentioned condition, “At least 80% of the standard yield of the neighboring areas shall be required when growing crops in the cropland under solar panels.,” some pointed out that, although conditions have been eased in cases of reutilizing devastated cropland, there is no standard to define the “100%” yield (yield per hectare) in the first place when cultivating crops that are not grown in the surrounding areas, and the ground for determining whether or not agricultural business is appropriately and continuously operated is not clear.

In addition, there are some cases where light shielding efficiency being around 30%, which is sufficient in general for many crops to grow, may lead to poor growth when devastated cropland is utilized. In such cases, sufficient soil improvement is necessary.

 

Future Prospects of Solar Sharing

As described above, solar sharing has many problems to be solved and points to be improved by future system improvement, flexible operation and support, etc., but it also has many advantages that general outdoor solar panels do not have. For example, panels in solar sharing are installed on the height of two meters or higher, which prevents any shadows over the panels. Also, it is easy to control weed since crops are grown under the panels and are managed by farmers.

As of the end of FY2020, the systems of “agriphotovoltaics” are mainly installed by power generators, which accounts for 63%, followed by farmers or cropland owners for 37%. Even if power generators install the system, part of the income from sales of electricity is given back to the farmers or cropland owners in some cases, thereby benefiting both the solar power providers and agricultural workers or cropland owners.

The key point of solar sharing in the future is to encourage the introduction of models that work harmoniously with local communities and agricultural areas, beyond the framework of solar power producers and farmers. In the models, the power generation systems will be incorporated into regional microgrids by taking the locational advantage of installing solar power generation systems in the upper part of cropland that is widely distributed throughout the country, including agricultural areas and suburban areas, and by utilizing renewable energy, privately owned electricity transmission lines, and electricity distributed lines in the region. These models as one of the diversified power sources by various power generation entities will include those enabling the use of power generated in the lower part of cropland; agricultural, forestry, and fishery facilities; and public facilities. In order to spread solar sharing in the future, it will be essential to promote the utilization in the models of approaches to supply energy stably and improve resilience in large-scale disasters and states of emergencies occurring in many places.