In the course of a year, the energy needed to power every vehicle, machine and factory on earth, as well as heat every building, is equal to about 50 trillion kilowatt-hours.

Or about 40 minutes worth of sunlight.

Here in Orange County, the energy released by the sun in the form of light and heat can total five million kilowatts on the brightest days.

That is more than double the generating capacity of San Onofre's twin nuclear reactors.

Abundant, cheap and clean energy. The promise of power in perpetuity. The solar age. Welcome to the late 1970s.

More than a decade later, the remnants of that age can be seen on rooftops across Orange County. Low black boxes called solar collectors are reminders of another energy crisis and the resulting scramble for alternative fuels. Homeowners did their part for energy conservation by installing solar hot water systems, while at the same time collecting hefty tax credits awarded by a grateful nation. The tax credits ended in 1985, and the home solar industry nearly did too.

"Everybody and their brother was manufacturing or installing solar equipment," recalled Mike Gallant, owner of Generic Electric in Orange. "After tax credits ended, it was a matter of months and the entire industry had been shaken out."

Gallant is a survivor of the solar massacre of 1985. Dozens of companies failed, big marketing firms washed their hands of the solar industry, and a once enthusiastic public ran back into the welcoming arms of the Southern California Gas Co. for its home heating needs. It seemed that the great solar experiment had gone into eclipse.

But a surprising thing happened on the way to oblivion. When Iraqi dictator Saddam Hussein stormed into tiny, oil-rich Kuwait, he may have also ridden inadvertently to the rescue of the solar home market in this country.

As the bully of Baghdad threatens to ignite the world's first energy war, the call for development of alternative energy sources and conservation of existing fuel supplies has sounded across the nation. Solar energy is suddenly fashionable again. Small wonder that a solar industry association in Florida recently indulged in some black humor when it nominated Saddam Hussein as its Solar Man of the Year.

Les Nelson, president of the California Solar Energy Industries Assn., says he believes the Middle East crisis will "probably lead to renewed interest in residential solar uses. Not that people are suddenly going to run out and put solar in their homes, but there should be some action (on solar energy) on a government level."