Grid connection requests processed by Japan’s grid operators grew considerably between Q4 2023 and Q4 2024, according to an OCCTO report released on March 14, 2025.
The number of preliminary consultations more than tripled from 5,217 in Q4 2023 to 16,123 in Q4 2024. Formal connection request submissions grew by 132%, from 1,706 to 3,958. While the grid operators responded to 187% more requests, the 3,509 responses in Q4 2024 were not enough to reduce the backlog size. Grid connection contract applications nearly doubled from 381 in Q4 2023 to 743 in Q4 2024.
Grid-scale battery storage made up 68% of the formal applications and, while the breakdown was not disclosed, likely a similar or higher share of preliminary consultations. Solar accounted for 30%, with the remainder split between wind, hydro, biomass, and other technologies.
About a half of the 743 contract applications was for solar power plants. Storage projects made up 40% of the total.
The number of new requests, both in the form of preliminary consultations and formal request submissions, grew across all ten TSO areas. Tokyo saw the most significant growth in preliminary consultations, which increased five-fold from 1,001 in Q4 2023 to 5,121 in Q4 2024. The number of consultations also more than quadrupled in Kyushu, more than tripled in Hokkaido and Chugoku, and at least doubled in Tohoku, Chubu, Shikoku, and Okinawa.
Formal requests more than quadrupled in Kyushu, more than tripled in Chugoku, and more than doubled in Tohoku, Tokyo, Chubu, Hokuriku, and Kansai.
Preliminary consultations dropped from about 23,000 in FY2017 to less than 10,000 in FY2020. They grew every year since, reaching almost 26,000 in FY2023. The rebound is primarily driven by a boom in grid-scale storage and non-FIT solar development.
