64.6MW Solar Plant to Be Built With 17.5MWh Battery in Hokkaido

Toshiba, TMEIC design entire system

2017/05/09 20:56
Kenji Kaneko, Nikkei BP Intelligence Group, CleanTech Institute
"Softbank Tomatoh Abira Solar Park," which started operations in 2015 (source: Nikkei BP)
A mega solar power plant equipped with a storage battery in Tokunoshima (source: Nikkei BP)
TMEIC's PV inverter was also employed for the plant in Tokunoshima. The plant uses the AC Link to reduce output fluctuation. (source: Nikkei BP)

SB Energy Corp and Mitsubishi UFJ Lease & Finance Co Ltd announced April 28, 2017, that they will build one of the largest-scale solar power plants equipped with a storage battery in Japan.

SB Energy (Minato-ku, Tokyo) is a company that is affiliated with the Softbank group and runs renewable energy-related businesses, etc. The mega (large-scale) solar power plant, "Softbank Tomatoh Abira Solar Park 2," will be built in Abira-cho, Yufutsu-gun, Hokkaido.

The total capacity of solar panels installed at the plant will be 64.6MW, and the total rated output of PV inverters will be 48MW. The capacity of the lithium-ion (Li-ion) rechargeable battery to be installed at the plant is 17.5MWh, and the rated output of power conditioners for the battery is 34MW.

Near the planned construction site, there is "Softbank Tomatoh Abira Solar Park," which started operations in 2015 with total solar panel and PV inverter capacities of 111MW and 79MW, respectively. But it is not equipped with a storage battery (See related article).

Softbank Tomatoh Abira Solar Park 2 uses the "AC Link" method, which conducts DC-AC conversion by using different power conditioners for the solar panels and storage battery, combines power into an AC current and transmits it to a power grid..

The solar panel and PV inverter employed for the plants are products of Toshiba Corp and Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC), respectively. Toshiba and TMEIC are also jointly responsible for the engineering and construction of the entire system including the battery.

SB Energy and Mitsubishi UFJ Lease & Finance plan to start construction of the plant in May 2017, aiming to start operations in fiscal 2020. The plant will be installed on about 900,000m2 (about 90ha) of land owned by Tomatoh (Tomakomai City, Hokkaido).

The plant will be run by Tomatoh Abira Solar Park 2 LLC, a fifty-fifty joint venture between SB Energy and Mitsubishi UFJ Lease & Finance. It is expected to generate about 71,477,000kWh of electricity, which is equivalent to the amount consumed by 19,854 households, per year.

Output fluctuation reduced by '1% per minute'

SB Energy and Mitsubishi UFJ Lease & Finance decided to install the storage battery to comply with the "Technical Requirements Regarding Measures to Reduce Output Fluctuation of Solar Power Generation Facilities," which Hokkaido Electric Power Co Inc (HEPCO) announced in April 2015.

The requirements are targeted at "measures against short-period fluctuation," which reduce the impact of the rapid fluctuation of solar power plants on the frequency of a power grid. After the amount of grid connection applications exceeds 400MW, HEPCO requires 2MW and higher-output solar power plants to comply with those technical requirements and install a storage battery.

Specifically, as an index, HEPCO announced the "fluctuation rate of 1% per minute," which reduces the fluctuation of the rated output of a mega solar plant to less than 1% of the rated output of PV inverters per minute in terms of power adjusted by charging/discharging a storage battery.

Mega solar plants that use a storage battery for measures against short-period fluctuation are operating in Tokunoshima (the Kyushu region of Japan) and Hidaka-cho, Hokkaido (See related article 2). In addition, several projects are underway in Hokkaido to build such power plants.

Among such projects that were announced in the past, a solar power plant in Chitose City with a total PV inverter capacity of 28MW (panel capacity: 39MW) and a battery capacity of 14MWh is the largest. But the scale of Softbank Tomatoh Abira Solar Park 2 will be even larger than that.

Also, the mega solar plant is required to comply with limitless/uncompensated output control (based on the designated power producer system) for grid connection. Under the feed-in tariff (FIT) policy, uncompensated output control can be imposed for up to 30 days (30-day rule).

However, under the designated power producer system, uncompensated output control can be imposed for more than 30 days, potentially affecting terms of financing. It is SB Energy's first project for which a project finance loan has been structured under the designated power producer system.

Output control under the 30-day rule and the designated power producer system is required when there is a possibility that power supply will exceed the power demand of the entire grid due to an increase in the amount of renewable energy-derived electricity, and the output of renewable energy-derived electricity is reduced by the hour. The storage battery for Softbank Tomatoh Abira Solar Park 2 is targeted at dealing with short-period fluctuation and is not expected to be used for output control by the hour.

The Ministry of Economy, Trade and Industry's subsidy for Sustainable open Innovation Initiative (SII) was not used for the introduction of the battery.