Last May President Jimmy Carter stood in the rain in Golden, Colo., celebrating Sun Day and said the nation "could meet as much as one-fourth of our energy demands from solar sources by the end of this century."

In the next few weeks, Carter will be asked to decide whether the government should spend tens of billions of dollars to develop solar energy aggressively, should move toward that goal slowly, or should adopt a low-cost and largely symbol-laden policy.

Carter's decision will cap a domestic policy review undertaken last May that will not only shape the future of solar energy programs, but could become a prickly political issue during Carter's 1980 bid for reelection.

The president's decision may settle a Cabinet-level debate over how high a priority to assign solar energy, how much to spend, and whether to create such institutions as a Solar Bank to provide low-cost financing for solar installations.

The options the president has to choose from are laid out in a 45-page policy memorandum completed last month, which said that solar energy could provide 20 percent or more of the nation's energy by the year 2000. The options include:

Continuing existing programs, and increasing spending only $160 million by 1985. It also assumes that solar would provide 10 percent of the nation's energy needs by the end of the century.

Roughly doubling federal spending to $2.5 billion by 1985, establishing a Solar Bank, and offering 30 percent investment tax credits for industry. This option assumes that solar could provide about 13 percent of the nation's energy by 2000.

Dramatically increasing spending from about half a billion dollars this year to $10 billion in 1981, with a total increase of $44 billion by 1985. This option assumes that the nation could get from 20 to 25 percent of its energy from the sun by the year 2000 and, among other things, would mandate that 20 percent of the nation's gasoline come from gasohol by the end of the century.

So far Treasury Secretary W. Michael Blumenthal and the Office of Management and Budget have vigorously opposed greatly increased spending on solar energy, or creation of the Solar Bank.

Blumenthal, in a Jan. 19 memo to the president obtained by The Washington Post, said that all the options "violate sound fiscal, tax and financial policy." The proposals to boost solar energy "are inconsistent with other policy determinations you have made," he told Carter.

OMB, in addition, has argued for better management of existing solar programs, saying that the administration's commitment to solar energy already is substantial.

The budget Carter has just sent Congress proposes an increase for solar programs in the Energy Department from $528 million to $597 million, in addition to sizable tax credits for solar installations. In 1974, the government spent only $14.8 million on solar energy.

While Energy Secretary James R. Schlesinger has yet to send a formal recommendation to President Carter or Stuart Eizenstat, Carter's chief domestic adviser, DOE officials say he is expected to support some variation of the second option -- gradual development. Within DOE, however, major divisions exist over support for specific programs, such as mandatory installation of solar collectors on new buildings.

Schlesinger will be joined by the head of the Council on Environmental Quality, Charles Warren, in opposing Blumenthal arguments against any stepped-up spending.CEQ member Gus Speth, one of the most vocal solar advocates, has pressed DOE and the White House to adopt a firm commitment to a 20 percent solar goal by the year 2000.

Some White House officials say that Carter is predisposed to select some variation of the middle option for political reasons alone. California Gov. Jerry Brown, Carter's expected challenger for the Democratic nomination in 1980, has consistently charged Carter with not doing enough about solar energy. The administration has also drawn similar fire from a growing number of congressmen and senators.

"The White House is growing very sensitive about solar energy politics," says a Energy Department official.

Herb Epstein, a member of the Solar Lobby, is quick to point out that in recent years the solar outlays enacted into law have been shaped by Congress and not by the president.

"Right now there are a lot of conflicting signals on solar within the administration. DOE, CEQ, and possibly EPA are pressing for an accelerated program. Treasury and OMB are pushing for the status quo. It is up to the president to make the right choice," Epstein says.

Epstein says the major fight is likely to be over appropriating hundreds of millions of dollars for the Solar Bank, and that decision will be the "litmus test of Carter's commitment" to solar energy.

Next week a coalition of pro-solar and environmental groups will unveil an alternative plan to the one the administration is expected to choose.

White House officials say the president's decision will be announced in either a message to Congress or a major speech. The forum the president chooses, they say, will depend on the size of the administration's commitment.