Segways Driven Between Arrays at 16MW Solar Plant in Mie
Maximum power generation, higher O&M efficiency pursued in parallel
The "Matsusaka Yamamuro Mega Solar Power Plant," a mega- (large-scale) solar power plant with a total solar panel capacity of about 16MW and a PV inverter capacity (grid capacity) of 12MW, is located next to the "Matsusaka Core Industrial Park" in Matsusaka City, Mie Prefecture, Japan (Fig. 1).
More than four years have passed since the plant began operation in December 2015. The power producer is Sanko Real Estate Co Ltd (Tsu City), a group company of Mie Kotsu Group Holdings Inc.
Sanko Real Estate has gradually narrowed down the space between arrays at its solar power plants as it accumulates experience. The arrays were spaced either 1.5m or 1.25m from each other at the beginning. The company had initially designed the space to be about 1.1m at the mega-solar plant in Matsusaka Yamamuro, but changed this layout halfway and narrowed the space down to about 1.0m (Fig. 2).
The company considers the minimum space between arrays is 1.0m. According to Sanko Real Estate, if the space is narrowed down any further, construction and maintenance efficiency, among others, will be affected too much.
Solar panels were tilted by 10°, just like at its other solar plants, in order to limit the impact of shadows. If the space is narrowed down this far, however, panels in the bottom row will be shaded for some time in winter. Yet the company cut the space between arrays considering the effect of boosting power generation through installing more panels was more beneficial compared with power generation loss due to the shade.
Even if some panels were shaded, compared with crystal silicon-type panels, power generation would decrease less with CIS chemical compound-type panels that Sanko Real Estate adopts. The company made the best use of this benefit in such a layout.
By joining hands with the same partner companies for construction and facility supply at almost all of its solar power plants, Sank Real Estate has deepened its relationship with those companies. Chiyoda Corp has provided engineering, procurement and construction (EPC) services, while CIS chemical compound-type solar panels of Solar Frontier KK and PV inverters of Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC) have always been adopted at these plants.
According to Sanko Real Estate, its efforts to deepen its relationship with the EPC constructor and power generation facility manufacturers have proven effective when considering mega-solar plant design.
With a view to boosting both the solar panel capacity and the grid capacity to be transmitted to an extra-high-voltage power grid, Sanko Real Estate negotiated with the Ministry of Economy, Trade and Industry and Chubu Electric Power Co Inc. As a result, the grid capacity was raised from about 8.8MW, which was the initial plan, to 10.5MW, while the solar panel capacity was increased from approximately 11.4MW to about 13.5MW.
Even after this revision to the plan, the project site still had more room for panels. Accordingly, the company obtained approval for a new facility and set up another mega-solar plant with an output of about 1.9MW, connecting it with a high-voltage grid near the site's north end.
Consequently, the mega-solar project was transformed into "plant No. 1" with a panel capacity of about 13.6MW and a grid capacity of 10.5MW, where the facility is connected with an extra-high-voltage power grid and generated power is sold at an approved unit price of 40 yen/kWh (excluding tax), and "plant No. 2" with a panel capacity of about 1.9MW and a grid capacity of 1.5MW, where the facility is connected with a high-voltage power grid and generated power is sold at 32 yen/kWh (excluding tax).