The $40,000 ballpark price for the Bergey Windpower Co.'s 10-kilowatt generator, including a power inverter and installation, is a big enough bite to discourage anyone, especially those who may not know how long they plan to live in the same place. [ Note: Mr. Sansome received a rebate of ~ $20,000 from the California Energy Commission. ]

Sansome has figured that his windmill will pay for itself in six to eight years. The life of the gadget is estimated to be 25 to 30 years, which equals a lot of free energy over a long period of time.

Southern California Edison representative Laura Rudison estimated more conservatively the span of time before the average homeowner would break even.

"When you really run the numbers, it may be 12 or 15 years," she said. [ if you ignore the CEC rebate ]

Rudison is the project manager for Edison's Net Metering Program, which does business with customers who generate their own electricity.

Because neither the wind nor the sun provide continuous sources of power, most of those who generate power from them also rely on Edison to provide power at night or on a calm day.

By using an electric meter that runs both backward and forward, the Net Metering Program allows small, private generators to barter the power they use for the power they generate on a one-to-one basis.