Homeowners considering solar and conservation improvements are entering a "distorted marketplace," solar advocate Denis Hayes charged recently.

Hayes said that the Reagan administration's massive subsidies to nuclear energy and to the oil and gas industry for synthetic fuel projects and the simultaneous cuts in funding for solar research are depriving consumers of energy options.

Hayes, the former head of the federal Solar Energy Research Institute (SERI) in Boulder, Colo., disagreed with the Reagan administration over energy priorities and was ousted last spring. He is now speaking out on energy issues. In a recent interview he questioned the administration's concentration of energy funding on the nuclear industry, while cutting funding for solar energy. Nuclear power can only be built and marketed by monopolies, he said, while solar energy production, in contrast, is "decentralized, composed of small vigorous entrepreneurs, and is no threat to the national security."

The solar industry, he declared, "could survive if the federal government would stay out of the energy business altogether."

Hayes said he was heartened by Congress' recent show of support for solar funding. He referred to the House resolution opposing the administration's suggested repeal or reduction of tax incentives for solar and conservation improvements and to Congress' revival of the Solar Bank.

The House solar incentive resolution was signed by 250 representatives, and a similar resolution in the Senate was signed by more than 50 senators.

"The sentiment in Congress is obviously very strong to keep these incentives," said Barry Piatt, press secretary to Rep. Tom Harkin (D-Iowa), who introduced the resolution in the House along with Rep. James Jefford (R-Vt.).

"The grassroots support for the tax incentive has really been unbelievable," said David Wilson, legislative assistant to Jefford. "The tax incentives are incredibly popular. I think the administration would have a very difficult time getting a repeal through Congress."

A House and Senate conference committee has recommended appropriation of $25 million for the Solar Energy and Energy Conservation Bank, which the Reagan administration had recommended scrapping. The Solar Bank was originally authorized to help low- and moderate-income families finance solar and conservation improvements.

While the House has approved appropriations for the Solar Bank, its actual operation is still "up in the air," said a spokesman for the Department of Housing and Urban Development, which administers the program. He said that the bank exists on paper but has no employes; the Senate must still approve its funding. But the president could ask that it be rescinded or deferred, he added.

The Solar Bank was set up to provide subsidies of up to $5,000.

New active and passive solar homes qualify for subisidies, as as well as solar retro-fitting. A wide range of conservation improvements would also be eligible, including caulking and weatherstripping, storm windows, insulation, and replacement burners, furnaces, and boilers.

Both the solar and the conservation improvements could be made to residential, multi-family, commercial, and agricultural buildings.

For some of the programs a family would have to make 80 percent or less of the median income for their area. For others, a family could make up to 120 percent of the area median income and still be eligible for a subsidy.

In the area of solar research, Hayes said that funds have already been slashed. (The SERI budget was cut from 130 million to 52 million.)

While some funding may be restored by Congress, Hayes said that many talented people have already left. Once a project is stopped he said it is difficult to start up again as the researchers go elsewhere.

Among projects he said were in jeopardy:

* Research into energy-efficient windows (which had been heavily funded by the research institute).

* Educational programs to help homebuilders modify their traditional designs to solar

* Consumer education programs specifying comparative energy use of various appliances and setting energy-efficiency standards

* An international marketing effort for solar technology

"If every window in every home in America were as energy efficient as we now know how to make them we would displace roughly half the energy equivalent of the oil we now import," Hayes said. This could mean a savings of 3 million barrels of oil a day, he added.

Solar-education programs could help revitalize the home-building industry, which has been languishing because of high interest rates, Hayes asserted.

"Builders are scared," he said. "They may have five houses out there that they can't unload. They have never done solar before, and they want someone to reassure them--to tell them that this will work and it will sell."

That's just what a SERI-funded program in Boulder did. The institute offered to pay the design fees for builders who consulted architects for solar modifications to their standard blueprints. The institute also agreed to monitor the houses and give the builders publicity.