An electrolyte tank in the building that stores the storage battery (source: HEPCO)
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Hokkaido Electric Power Co Inc (HEPCO) and Sumitomo Electric Industries (SEI) Ltd announced Dec 25, 2015, that they have completed a large-scale storage battery system at Minamihayakita Transformer Station in Abira-chou, Hokkaido, and started to test the system.

The two companies installed a redox flow battery manufactured by SEI. It has a rated output of 15MW and a capacity of 60MWh and is one of the world's largest redox flow batteries in operation.

In the verification project, which will last for about three years, HEPCO and SEI will verify the performance of the system as a new system for adjusting the output fluctuation of wind and solar power generation facilities and develop optimal control technologies.

Specifically, they will verify the following items: (1) "measure against short-period fluctuation," which charges and discharges the battery in response to rapid output fluctuations (in units of seconds) of solar and wind power generation facilities in the aim of reducing frequency fluctuation, (2) "measure against long-period fluctuation," which levels supply-demand balance by predicting the output fluctuation of solar and wind power generation facilities by the hour, (3) "measure to ensure the capacity to reduce thermal power generation" in case an output reduction at thermal power plants cannot catch up with a rapid output increase in solar/wind power generation, (4) evaluation of the redox flow battery's performance, (5) evaluation of the large-scale storage battery system's performance, (6) evaluation of the system efficiency, etc.

For the verification project, HEPCO and SEI applied for the "Emergency Verification Project for Large-scale Storage Battery System in 2012," for which Japan's Ministry of Economy, Trade and Industry (METI) called for proposals via New Energy Promotion Council (general incorporated association). And their project was selected as a subsidized project.

In Abira-chou, where Minamihayakita Transformer Station is located, SoftBank Tomatoh Abira Solar Park, which is one of the largest-scale solar power plants in Japan, started operations Dec 6, 2015. The solar panel capacity and grid capacity of the plant are about 111MW and 79MW, respectively.