Solar panels on roofs and verandas are becoming a more familiar sight in Japan as people acquire the systems with help from subsidies amid government efforts to curb carbon dioxide emissions and combat global warming.

In addition to the subsidies from the national and local governments, the increase in solar-cell systems for household power is being driven by utilities’ purchases of surplus electricity.

Although power systems generated by wind, waste incineration and fuel batteries are also being promoted, relatively easy to install solar panels are “the most diffusive (alternative) power source in Japan,” an official of New Energy Foundation said.

Japan is already the largest producer of solar power in the world. But to expand its use on a wider scale, costs need to be reduced further.

Sharp Corp., which produces nearly half of the solar cells used in such systems, says its production has been increasing rapidly as environmental concerns grow.

The company expects its sales of solar cells in the current business year to soar 55 percent over the previous year to hit 49 billion yen.

Sharp plans to boost the production capacity of its Shinjo plant in Nara Prefecture.

The sun is an inexhaustible energy source and solar cells produce clean power that does not generate carbon dioxide or noise.

Since they have a long life span and require little or no maintenance, solar cells have scores of applications, including powering unmanned lighthouses and communications systems in satellites.

In a recent shift, however, their most prevalent use has been to generate household electricity.

As of the end of March, about 81,000 homes had solar panels, and according to New Energy Foundation the number is expected to rise to more than 100,000 by the end of this fiscal year.

The number increased conspicuously after the Great Hanshin Earthquake of 1995.

“This seems to indicate that people have come to understand the importance of a secure energy source being available in the event of a natural disaster,” the foundation official said.

Last year, household solar cells nationwide generated about 300,000 kw, accounting for more than 40 percent of the power generated by such systems worldwide.

Tokyo Electric Power Co. says the figure is equal to the output of a midsize thermal power plant.

To promote solar power use, the national government is providing subsidies of 100,000 yen per kw this year, and 229 local governments have introduced their own subsidy systems that can be added to the national subsidies.

Household solar cells ran as much as 2 million yen per kw to install in fiscal 1994, when the government subsidy program began. In fiscal 2001, they cost an estimated 768,000 yen.

Sekisui Heim, a home builder affiliated with Sekisui Chemical Co., says it will install a system in a new house for 500,000 yen per kw.

The company says it has reduced costs by bulk buying and simplifying installation work.

The most common solar-sell system that is installed in standard houses has the capacity to produce 3 kw of power.

According to Sekisui Heim, if a 3-kw system was installed at a total cost of 1.2 million yen, reflecting 300,000 yen in subsidies, “the system would pay for itself in 15 to 16 years, as it generates 79,000 yen worth of electricity a year.”

Households that generate more electricity than they consume during daylight hours can sell the surplus to utilities at the same price the electricity is sold to conventional households.

Figures show that on average, as much as 56 percent of the electricity generated by household power systems nationwide is sold to power companies.

Because solar systems generate power only when exposed to sunlight, houses must rely on electricity from the power companies at night.

The government has set a goal of increasing household solar power generation by 16 times to 4.8 million kw by 2010.

However, the cost of such systems still remains high. To expand their use, it is necessary to further reduce production costs and develop new technology.

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