The “Niigata Tobu Solar Power Plant”

The “Niigata Tobu Solar Power Plant” is a mega- (large-scale) solar power plant with a total output of about 22.65MW (grid connection: 17MW) located in Niigata Tobu Industrial Complex. Niigata Prefecture Bureau of Public Enterprise is the power producer of all the units in the plant.

The Unit No. 1 solar power generation system is characterized by its operation, which sets the solar panels at a different angle in summer and winter (Fig. 2). This is enabled by a movable mounting system.

Mega-solar power plants in snowy areas such as Agano City face two major challenges in an effort to secure a certain amount of power generation. One is the decrease in power generation caused by snow covering the solar panels during the snowy season. The other is that the amount of power generation tends to fall due to numerous cloudy days even during the sunny seasons from spring to fall, compared with areas on the Pacific Ocean side.

A movable mounting system was the solution to both of these two challenges. The angle of solar panels can be manually changed to 20 and 40°.

The solar panels are tilted to 40° during winter so any snow on the panels can easily fall off while they are tilted to 20° from spring to fall when the culmination altitude gets higher so a greater amount of power generation can be secured.

Along with this 1MW-output solar power generation system, 9kW-output automatic tracking-type power generation systems were installed. One 4.5kW-output single-axis type and another 4.5kW-output dual-axis type were set up (Fig. 3).

A special joint venture (JV) formed by Mitsubishi Electric Plant Engineering Corp and Ryodensya Corp provided the engineering, procurement and construction (EPC) services to Unit No. 1. Mitsubishi Electric Corp’s polycrystalline silicon panel and GS Yuasa Corp’s PV inverter were adopted.

From Unit No. 2 onward, all solar panels have been tilted to 30° all the time (Fig. 4) and set up 180cm from the ground. The base of the panels was set at 180cm, assuming that snow that slips off the panels could accumulate to 50cm over the maximum annual snow cover of 130cm in Agano City.

Toshiba Corp provided the ECP services to Unit No. 2. Single-crystal silicon solar panels manufactured by LG Electronics Inc of Korea and Toshiba Mitsubishi-Electric Industrial Systems Corp’s (TMEIC) PV inverters (500kW-output product x 2) were adopted.

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