While battery projects in Japan typically have durations of three to four hours, longer-duration projects are becoming more common, partly because the most recent long-term decarbonization auction was open only to assets with durations of six hours or more. Extending duration from four to six hours increased captured spreads by a relatively consistent 27% to 33% across the nine mainland TSO areas during the 365 days ended May 30, 2026. The absolute gain varied more significantly, however, ranging from about ¥9,000/MW per day in Shikoku to nearly ¥14,000/MW per day in Hokkaido.

Agrisolar projects are gaining interest both as land available for traditional development becomes increasingly limited and because of the technology’s potential to provide additional income for farmers. With the number of agricultural land conversion permits on the rise and nearly a quarter of operational projects experiencing some form of farming disruption, the Ministry of Agriculture, Forestry, and Fisheries is discussing what constitutes “desirable agrisolar” and what measures should be implemented to prevent unsuitable development.

With relatively low demand, inflexible baseload generation, and limited interconnection capacity with other areas, Shikoku is structurally prone to power oversupply that can push off-peak prices down. May 15, 2026, was an extreme example: day-ahead prices cleared at or near the floor for most of the day. Yet the day’s average price of 0.49 yen/kWh was only the fourth-lowest for the region on record, following three March 2025 days affected by an interconnector outage.