1.4MW Solar Plant in Toyama Directly Hit by Ferocious Winter Lightning
Annual power sale affected by snow accumulation
The "NiX Yatsuo Solar Power," a mega (large-scale) solar power plant with 1.416MW of output from solar panels and 1.26MW of output for grid connection, is in the mountains of Yatsuo Town in Toyama City, Toyama Prefecture, Japan. About four and a half years have passed since power sale was started Oct 1, 2014 (Fig. 1, See related article).
The mega solar power plant was constructed on a site where soil was collected to restore rice fields polluted by cadmium. The plant was developed by construction consultant NiX Co Ltd of Toyama City, using the former soil collection site owned by Toyama City. The power producer is NiX New Energy Co Ltd, which is a subsidiary of NiX and generates renewable energies.
NiX is engaged in the energy management business with a focus on renewable energy generation, setting the construction consulting business as its core.
3 negative factors including Hokuriku weather overcome
The company had to overcome three negative factors that lower the profitability in developing the mega solar power plant in Yatsuo Town. Two of the three factors were weather conditions unique to solar power plants in the Hokuriku region.
One of the factors is the lower intensity of solar radiation in the region, compared with other regions in Japan, due to the location of Hokuriku. The second factor is that the plant is in a snowy area.
The third factor is the configuration of the site, which consists of small plots of land extending from south to north (Fig. 2). The site is divided into the north block and the south block, and they are on both sides of a road. Moreover, many of the plots were not rectangular in shape. Because of this, it was difficult to arrange the solar panels effectively, and the total length of cables, as well as the total length of fences around the site, increases, resulting in a comparatively higher amount of equipment investment.
The land is leased for 25 yen per square meter. The total investment was approximately 390 million yen (approx US$3.6 million) and the power sale amount per year is estimated at about 44 million yen. The construction cost per equipment capacity was lowered to 275,000 yen/kW, which is equivalent to the construction cost of mega solar power plants on Japan's Pacific side based on the price at the time of construction, aiming to recover the invested amount in about 14 years.
PV inverters considered to be high capacity in those days, featuring 630kW of rated output and supporting 1,000V, were used. Because of the high capacity, the northern side (749.3kW) and the southern side (666.7kW) were respectively covered by one PV inverter. The number of panels per string (a unit of connected solar panels) was increased and the DC circuit from the panels to the PV inverter was designed to support 1,000V to reduce the number of combiner boxes and shorten the total length of cables. Power loss during power transmission was also minimized by this method.
Solar panels manufactured by Next Energy & Resources Co Ltd of Komagane City, Nagano Prefecture, were used. The plant has 4,800 polycrystalline silicon-type (295W/sheet) panels arranged on the site. PV inverters manufactured by Toshiba Mitsubishi Electric Industrial Systems Corp (TMEIC) were incorporated. The plant used PV inverters featuring 630kW of output and supporting 1,000V of DC input for the first time in the Hokuriku region.