HOKUTO, Yamanashi — A city that is home to a large-scale photovoltaic power generation system is gaining attention in the wake of the accident at the Fukushima No. 1 Nuclear Power Plant.
The Hokuto Site, a solar power facility in the Yamanashi Prefecture city of Hokuto, “provides electricity to some 1,000 households in our city,” according to Hiroo Uematsu, an official with the Hokuto Municipal Government’s environment division.
A two-hour drive from central Tokyo, Hokuto is known as a resort city surrounded by Mount Yatsugatake and Mount Kaikomagatake, where annual daylight hours reach roughly 2,300 — the nation’s longest. Because of the locational advantage, a private company is planning to build another photovoltaic power generation system adjacent to the Hokuto Site.
The Hokuto Site was originally a demonstration experiment facility run by the New Energy and Industrial Technology Development Organization (NEDO), an independent administrative agency. After a five-year experiment, the facility was handed over to the city for free in April this year.
At the approximately six-hectare site lie some 12,000 solar battery panels of 27 varieties from Japan and eight other countries overseas, generating 2.2 million kilowatt hours of electricity per year.
The city sells the electricity to a major trading company for 15 yen per kilowatt hour and expects to generate 33 million yen in revenue this fiscal year.
“After deducting the land lease and other expenses, some 14 million yen in profit will be directed to expanding the subsidies for installing solar panels to housing units,” said Uematsu. The city aims to become a leading municipality in the promotion of renewable energy by introducing solar power into many households, elementary and junior high schools and other public facilities.
Running the facility, however, is not easy. Solar power generation’s electricity conversion efficiency is low at up to 15 percent, while the power generation cost is some 40 yen per kilowatt hour — more than that of wind power generation (slightly over 10 yen) and other renewable energy resources.
The Hokuto Site has so far been profitable simply because the city took over the facility free of charge and did not have to cover the construction cost of nearly 1 billion yen.
“The facility could fall into the red after about 10 years, when we’ll need to fork out expenses to replace panels and other renovation costs,” said Uematsu.
Solar power generation is also susceptible to the weather, with its output plummeting on cloudy or rainy days. At the nation’s largest photovoltaic power plant in Sakai, Osaka Prefecture, its operator Kansai Electric Power Co. (KEPCO) has introduced an energy storage facility accommodating 48 nickel hydride batteries near KEPCO’s substation in order to “overcome the shortcomings” of solar energy generation, according to a KEPCO official.
At the 20-hectare plant in Sakai with some 70,000 solar panels, up to 10,000 kilowatts of electricity is generated during the current trial run ahead of the full operation starting in October. On cloudy and rainy days, however, the output drops to around 5,000 kilowatts and 2,000 kilowatts, respectively. To make up for the gap and achieve stable supply, KEPCO plans to release electricity accumulated in the energy storage facility on sunny days.
Since the utility did not adopt highly-efficient lithium-ion batteries at the energy storage facility for financial reasons, there is a limit to the amount of electricity it can cover on bad weather days. Despite being the nation’s largest photovoltaic power plant, its output is roughly one-hundredth of that of a nuclear reactor. “Considering the vast premises it requires, its output is low,” one KEPCO official says.
In anticipation of the Diet passage of a bill to oblige utilities to buy electricity generated by renewable energy sources such as solar and wind power, SoftBank Corp. President Masayoshi Son has announced a plan to construct large-scale photovoltaic power generation plants at more than 10 locations across the country. Son has demanded the price for which utilities buy electricity generated by renewable energy sources be set high, saying in a recent interview with the Mainichi, “If a price somewhere in the lower half of the 30-40 yen (per kilowatt-hour) level was set, all solar power projects would falter.”
It is feared, however, that the price rise would be passed over to consumers in their energy bills.