When Iraqi leader Saddam Hussein plowed into Kuwait last week, he may have partially shut off Mideast oil supplies to the United States, but he also pried open the valve on a U.S. constituency that has been in the shadows for the past decade.

Researchers, manufacturers and activists in the renewable energy and energy conservation fields -- with "I-told-you-so's" sliding off their lips -- are eagerly watching the Energy Department to see if it uses the crisis to jump-start the nation's conservation consciousness and to elevate the profile of the official who would lead the charge: J. Michael Davis.

Davis, assistant secretary for conservation and renewable energy since October, is charged with developing and promoting programs to step up the production and use of renewable energies -- solar, biomass, wind, geothermal, alcohol fuels. His job is also to promote energy-saving technologies and measures related to transportation, construction and industrial production, and the funding of programs and research on the state level.

For the most part, Davis, 43, has received high marks from the trade associations, environmentalists, Capitol Hill staff aides and others who witnessed the Reagan administration's raid on the renewable energy and conservation budget. "Cautiously optimistic" is the buzzword among these groups when it comes to Davis's ability to make effective change.

"After eight years of Reagan and people who didn't give a damn about us, I was very enthusiastic," said Scott Sklar, executive director of the Solar Energy Industries Association. "I'm watching him like a hawk."

What may help him, they say, is his military-business background, a rarity among solar-power advocates more often associated with anti-establishment values and back-to-nature lifestyles.

In the days following the gulf crisis, Davis and other top Energy officials have met with the major utility, automobile and vehicle operator businesses in the country to negotiate and discuss what is likely to translate next week into the administration's or the department's appeal to the nation for energy conservation.

An engineer, Davis graduated from the Air Force Academy in 1969 and served in Vietnam, where he first realized, he said, that the development problems of the Third World were related to their dependence on expensive imported energy sources.

When he returned to the United States as an Air Force Academy faculty member, he spun his academic assignment into a research project, developing a solar energy curriculum and building a solar-powered house.

In 1977, Davis joined the Energy Department and three years later worked at the Solar Energy Research Institute, a government-owned, privately operated center in Golden, Colo. The institute is the government's main laboratory for research, testing and development of solar and renewable energy.

Davis left the institute shortly after the Reagan administration took over and "we hit a major policy shift" away from funding and interest in nontraditional energy resources. "I decided there was no sense in arguing with that," he said.

Suncatcher, the Denver solar engineering firm he created after leaving the government, grew to a $1 million-a-month business with 300 employees. When tax credits for solar industry vanished in 1985, the company turned to designing energy-saving systems.

As assistant secretary, Davis put much of his effort in the beginning into restructuring his department along the lines of how energy is used -- the transportation sector, the construction sector, the utilities sector -- to make his office more accessible and relevant to commercial, industrial and private consumers.

"My favorite topics," he said dryly, "are sectors . . . supply and demand and short-term, long-term."

Davis has presided over the first administration budget request in a decade that is actually larger than Congress's request. But watchdogs are not sure whether it was Davis or his boss, Energy Secretary James D. Watkins, who convinced the Office of Management and Budget to ease up on its fiscal club.

This year the administration is asking Congress for $683 million for conservation efforts and renewable fuels programs and research, the first increase in the department's budget request since 1985.

"The guy is not slick, with all the positive and negative connotations that go with that," said a House staff member who believes Davis's is slightly uncomfortable working the Hill. "But he's straightforward. He wants to argue on the merits of things."

Under Davis, the department is also planning a major energy-saving lighting renovation project for government buildings that will cost the department $1 million and the General Services Administration and Pepco up to $10 million each. It will soon launch an energy-saving program with the Housing and Urban Development Department, part of which will include requiring contractors to retrofit homes in the HUD rehabilitation program with energy-saving devices.

Davis is otherwise an understated man whose expression changes little as he speaks. But let him talk about his days making solar energy systems and his whole body leans forward in his chair, and out comes a prolonged smile.

Sounds like fun. "You bet," he replies. "I still have working systems" in place in Colorado, he adds quickly.

Asked about the probability of turn around the legacy he inherited, he replied, "There's no sense complaining about anything. Let's get busy."