A storage battery installed for a mega solar plant in Shiriuchi-cho, Hokkaido (source: Nikkei BP)
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SB Energy Corp (Minato-ku, Tokyo) and Mitsubishi UFJ Lease & Finance Co Ltd (Chiyoda-ku, Tokyo) announced Nov 1, 2017, that they will build a mega (large-scale) solar power plant with a storage battery in Yakumo-cho, Futami-gun, Hokkaido, Japan.

SB Energy is a company that is affiliated with the Softbank group and runs renewable energy-related businesses, etc.

The solar power plant, "Softbank Yakumo Solar Park," will be run by Hokkaido Yakumo Solar Park LLC, a fifty-fifty joint venture between SB Energy and Mitsubishi UFJ Lease & Finance. The construction of the plant will start in April 2018 with an aim to start operations within fiscal 2020. The plant will be built on a former pasture land (area: about 132ha) owned by Taiheiyo Kisen Kaisha Ltd (Chiyoda-ku, Tokyo) and Taiheiyo Nojo Co Inc (Futami-gun, Hokkaido).

The total capacity of solar panels to be installed at the plant is about 102.3MW. The plant is expected to generate about 100,682,000kWh of electricity, which is equivalent to the amount consumed by 27,967 households, per year. The FIT tariff set for the plant is ¥36/kWh.

A joint venture (JV) between Toshiba Corp and Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC) provides EPC (engineering, procurement and construction) and O&M (operation and maintenance) services for the plant. The solar panel and PV inverter employed for the plant are products of Toshiba and TMEIC, respectively.

Based on the "technical requirements concerning measures against the output fluctuation of solar power generation facilities," which Hokkaido Electric Power Co Inc (HEPCO) announced in April 2015, a storage battery will be set up at the plant as a measure against the short-period fluctuation of the output of the mega solar plant.

An lithium-ion (Li-ion) battery with a capacity of about 27MWh will be installed. The rated output of the power conditioner for the battery is 52.5MW. And the plant is one of the largest-scale solar power plants equipped with a storage battery in Japan.

Also, the grid connection of the plant was applied for after the "output control limit of 30 days, etc" in the service area of HEPCO was exceeded, requiring "limitless/uncompensated output restriction" for grid connection. This time, a project financing loan was successfully structured even under such conditions.

In Hokkaido, there is an increasing number of mega solar projects using a large-size storage battery as a measure against the short-period fluctuation of power grid frequency.