Japanese solar building up resiliency against curtailment

Japan's Mitsubishi Corp. and Japanese utility Kyushu Electric Power Co. are teaming up with Tokyo-based battery supplier NTT Anode Energy (NTTAE), a subsidiary of Japanese telecoms group Nippon Telegraph and Telephone Corp. (NTT), to use grid-scale battery storage to reduce the impact of solar curtailment on the island of Kyushu, in southern Japan.

“By spring 2022, solar power curtailment has been carried out in Kyushu region, where solar power spreads even earlier in Japan,” Mitsubishi said in a statement. “Solar power curtailment has been carried out in several regions other than Kyushu, such as Shikoku, Chugoku and Tohoku area in Japan.”

Japan's Ministry of Economy, Trade and Industry (METI) issued its first “Power Crunch Alert” for the Tokyo Region in mid-March, after an earthquake hit the area.

“Under these unstable circumstances, effective utilization of excessive electricity should be one of the essential ways to secure stable power supply,” Mitsubishi explained. “Considering the situation, we have agreed into collaboration to establish a business model to utilize grid-scale battery storage for restriction of solar power curtailment and trading electricity in various electricity markets.”

The three companies plan to use grid-scale battery storage installed by NTTAE, in order to effectively use excess power and stabilize power supplies. The first 4.2 MWh facility will be deployed in Fukuoka and is expected to begin commercial operations in February 2023.

According to Japan's Institute for Sustainable Energy Policies (ISEP), the island of Kyushu had around 10.5 GW of PV and 600 MW of wind capacity installed under the country's feed-in scheme by the end of 2021. The curtailment rate in the region for the entire year was estimated at around 4.4%, up from 3.8% in the preceding year.

“In addition, about 4 GW of nuclear power generation is in operation at any given time, and the VRE output curtailment is also greatly affected by the operation of these nuclear power plants,” said ISEP.

The energy sources are curtailed on the island in the following order of prioritization: thermal, biomass, solar and wind, hydroelectric, nuclear, and geothermal.

“The use of pumped hydro storage and storage batteries is effective, but further promotion and optimization of online control of VRE, review of the minimum output of thermal power generation, demand response and virtual power plants are required,” said ISEP.