Solar Air Conditioners: Brownout Insurance For Japan?

As the mercury climbs in Japan this summer, electric pow er companies may be in a cold sweat. Even in a good year, Japanese power supplies barely outstrip demand as families in crowded cities such as Tokyo and Osaka reach for the air-conditioner switch. This year, with a half-dozen nuclear power plants shuttered because of accidents or inspections, industry officials are predicting brownouts.

Figuring the situation can only get worse, Kansai Electric Power Co. and Sharp Corp. are now testing an experimental, solar-powered air conditioner-cum-heater. The system will incorporate a unique interface circuit that efficiently mixes solar power with conventional electricity. Under sunny skies, a roof-mounted solar panel will supply enough power to cool a two-story house in summer or heat it in winter. When the clouds roll in, the circuit will automatically supplement the battery power with juice from the wall socket. One problem is that generating enough energy to cool an average home will require a solar panel of more than 200 square feet. Kansai Electric is now working on reducing this size, which is unwieldy for small Japanese rooftops.

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