The "Tahara Solar Wind Power Plant," a hybrid power plant combining solar and wind power constructed by seven companies including Mitsui Chemicals Inc, started operation Oct 1, 2014 (Fig. 1).
In addition to the mega-solar power plant consisting of 214,560 solar panels (total capacity of 50MW with 35MW PV inverters), three 2MW-output large wind turbines (total capacity of 6MW) were set up on the site (Fig. 2). Capital investment totaled approximately ¥18 billion (approx US$152 million).
Expecting roughly 67,500MWh power generation per year combining solar and wind power, the plant sells the entire amount of generated power to Chubu Electric Power Co Inc. This amount corresponds to the power consumption of 19,000 households, which account for about 90% of all households in Tahara City. This is reportedly the largest hybrid power plant combining solar and wind power in Japan.
TMEIC's PV inverter, Hitachi's wind power generation system, panels by 4 companies
Four kinds of panels were installed. The breakdown is: 26MW of LG Electronics Inc's single crystal silicon type (Fig. 3), 20MW each of Kyocera Corp's (Fig. 4) and Sharp Corp's (Fig. 5) polycrystalline silicon type and 4MW of Solar Frontier KK's CIS compound type. As you walk along the central maintenance road from the entrance toward the sea, you can see these four kinds of panels in order and easily recognize the color and stripe variations in the square cells (power generating elements).
The plant also adopted PV inverters manufactured by Toshiba Mitsubishi-Electric Industrial Systems Corp (TMEIC) (Fig. 7). Seventy units of a 500kW product were set up with two units installed side by side in each area. As for the mounting system and the foundation, proprietary mounting systems made of alloy plating steel board are supported with concrete foundations (Fig. 8). Toshiba Corp provided the overall EPC (engineering, procurement and construction) services for the mega-solar power plant.
Three huge wind turbines with an output of 2MW each are standing along the quay outside the fence surrounding the mega-solar power plant. The height of the towers is 80m, and the three revolving blades are 40m each in length (Fig. 9). At the bottom of the towers are the PV inverters. The three wind power generation facilities are all products of Hitachi Ltd, and Mitsui Engineering & Shipbuilding Co Ltd was responsible for the EPC services for them.
'In winter, power is equally generated by solar and wind'
At the grid station near the power plant's entrance, the power transmitted from the mega-solar and wind power facilities is respectively boosted by voltage inverters and transmitted to Chubu Electric Power's high-voltage cable all together (Fig. 10). The plant set up a small meter for wind power and a large meter for the entire power plant to estimate the amount of power sold.
The amount of wind power uses the value of the small meter, and the amount of solar power is calculated by deducting the small meter's value from that of the large meter. The amount of power sales is calculated by multiplying each of the unit prices by the amount of power generated.
Although the solar power capacity, 35MW, is nearly six times larger than that of the wind power, 6MW, at the "Tahara Solar Wind Power Plant," the ratio of power generation could be smaller, at 3:1. Especially in the waterfront areas of Tahara City, the wind grows stronger, and the amount of sunshine decreases in winter.
"Although the amount of solar power generation outperforms that of wind power in summer, we expect the amounts to be equal in winter," said Shin Fukuda, executive officer and general manager of the Environment & Energy Business Development Division, Mitsui Chemicals.
Regarding the parallel establishment of solar and wind power generation facilities, the company is considering verifying its effects of leveling and lowering loads on the power grid in collaboration with Chubu Electric Power, he said.