The oil cartel gripped the United States in an energy stranglehold in 1973, creating problems for motorists and opportunities for entrepreneurs. Figuring that renewable energy systems would soon be hot items, Jay Carter Sr. and his son, Jay Jr., combined their engineering skills to start Carter Wind Systems Inc., in Burkburnett, Tex. They spent the next several years developing wind turbines. In 1978, Congress passed the first of two hefty tax credits for alternative energy installations, and the company racked up $5 million in sales last year.

Hundreds of makers of energy systems owe their fortunes to the tax credits. But the industry has a dubious future because Uncle Sam isn't smiling anymore. The credits expire in December of 1985, and it is doubtful that they will be renewed. "Energy tax credits are a small part of the general concern over the federal deficit," says Thomas Gray, executive director of the American Wind Energy Association. "But we're swimming against the tide. Congress is trying to raise money, so that works against us."

An aide to Rep. Fortney H. Stark (D-Calif.), one of the industry's fiercest adversaries, says that it is "highly unlikely" that the credits will survive. The Senate and the House agreed at conference to drop the credits during deficit-reduction hearings last June, but Rep. Dan Rostenkowski (D-Ill), chairman of the House Ways and Means Committee, plans to hold hearings on the issue early next year.

There are about 250 U.S. wind and solar equipment makers. In the solar industry alone, sales have grown from $17 million in 1976 to $1 billion in 1983. But without federal tax credits, consumers may find new equipment too costly. That could be the end for dozens of small manufacturers unable to lower prices to affordable levels.