Bright sunlight was shining down on Mayor David C. Crawford's head here this morning and Crawford, as befits a man whose city has just been chosen as the nation's new solar energy capital, was beaming right back.

"This thing," said the 57-year-old mayor of Golden and proprietor of the Golden Mercantile Mart, "is going to put our little town right in the middle of the map."

After some unusually heavy political infighting involving 16 states and 19 of the nation's leading private research institutes, the Energy Research and Development Administration announced Thursday - after a year-long search - that Golden will be the home of the Solar Energy Research Institute.

While the institute's initial $4 million to $6 million and 75 jobs are modest by most federal standards, officials involved in the project estimate the long-term benefits from it will be immense as national involvement with solar power picks up steam.

In addition to becoming the center for the government's study of converting sunlight into electricity, the institute will handle federal contracts on solar heating and cooling, thermal power generation, and wind and ocean power generation, according to ERDA.

The federal project is also a planner's delight, promising substantial future growth, the possibility of thousands of new jobs, long-term federal payrolls and spinoffs of much sought-after "clean industry" such as architecture and other planning connected with the project.

"I don't think anyone can really say what it will mean but solar is going to play a key part in the nation's future energy solution," said James Schefter, a spokesman for the Midwest Research Institute, a Kansas City research group that put together Colorado's winning bid.

"It could make the area around Golden what Houston is now to manned space flights," he said.

With that in mind, some of the country's biggest political names lobbied intensely for the solar research institutes for their states. Among those who ERDA officials said made strong, personal arguments to the Carter administration for the project were Sen. Edward M. Kennedy (D-Mass.) and Herbert Humphrey (D-Minn.) and California Gov. Edmund G. Brown Jr.

A measure of the project's political sensitivity was that the administration last week hastily threw together a secondary plan for three or four regional solar projects in order to ease the pain for the losers. Under the plan, one regional project will go to the Boston area, one to the Southeast and one in the upper Midwest.

"The jockeying was very intense," said a federal energy official. "Some very high administration people were talking to the losers this week."

There was speculation today from some state officials here that one of the reasons Colorado won the solar sweepstakes was to compensate the state for the federal projects it may loose under recommendations by the Carter administration. Five of the 30 water projects under review by the administration are in Colorado.

However, Raymond H. Fields, head of the five-member ERDA site selection committee for the solar project, said that the decision was made on a rating system bases on each applicant's management plan, key personnel and manpower reserves. ERDA also required the state it select to provide 300 acres for the institute.

Fields said his committee met for two days with individual applicants around the country. Neither the amount of available sunlight not political pressure was a relevant factor in the committee's recommendations, he said.

The committee met with ERDA acting director Robert Fri last week and spent three hours unanimously recommending the Colorado site. Fri made the decision, which was announced Thursday.

The decision caught some applicants off guards. Arizona officials unhappily confessed after the announcement that they had thought their only competition was from New Mexico, while Georgia Gov, George D. Busbee complained that his state has been rejected in order not to show favor to the President's home state.

The institute will be built here on South Table Mountain, a mesa towering high [WORDS ILLEGIBLE] 800 people [WORDS ILLEGIBLE] the foothills [WORDS ILLEGIBLE]

Golden already [WORDS ILLEGIBLE] measure of [WORDS ILLEGIBLE] home of the [WORDS ILLEGIBLE] Coors employs nearly [WORDS ILLEGIBLE] as a result the [WORDS ILLEGIBLE] high unemployment or [WORDS ILLEGIBLE] to expand as rapidly [WORDS ILLEGIBLE] other Denver suburbs.

The reaction here to the federal solar institute has been low-key enthusiasm.

"They came to us last year and asked if they could get the site up there on the mountain would we be interested," said Crawford as several of his customers leafed through a local newspaper that headlined the community's selection.

"We said sure," said Crawford. But no one is too excited. At least not yet." CAPTION: Picture 1, Major Crawford, proprietor of the Mercantile Mart, stands on main street of Golden, selected as site of the nation's Solar Energy Research Institute.; Picture 2, The community of 14,800 also includes a Coors brewery [WORDS ILLEGIBLE]