This is a story about a Hungarian count and his countess about solar energy, about riches to rags. It is about an arthritic inventor who plays Chopin and desiccates sludge.

The countess is the inventor. She is one of the world's pioneers in solar energy, having designed and obtained nine patents on solar devices. Yet she and her husband, who is an engineer as well as a count, have made virtually nothing on the inventions.

They live and work in a two-story house just north of Princeton, N.J., which is, appropriately, just down the road from a place called the Solar Motel. Inappropriately, the house is shrouded by trees. Because they love their trees too much to cut them down and let in the sun, they can't install one of their inventions, a solar heating panel, to cut down their heating bill.

Stella and Imre Andrassy live on Social Security, and little else. They bought the house in 1959 because it was "small and cheap." They complain bitterly, like many old people, about rising utility, heating and tax bills. Unlike most everybody, they fight back against the utility companies.

The house's small swimming pool, out back in the sun, has been heating panel. The fight against the utility companies - that is to say, the solar research - goes on in the basement laboratory. The lab connot be described, however, because the Andrassys won't let anybody down there. They fear patent theft.

Stella Andrassy's eyeglasses are held together with shiny black electrical tape and nylon fish line. She sat on them recently and she fixed them.

She is a heavy-set woman who walks haltingly and hunched-over, with pain and two canes. She will not say how old she is, but she was 16 when she met her husband - that was just after World War I ended in 1918. She is Swedish-born, speaks seven languages and reads Chinese philosophy (not in Chinese). When she laughs, her face, beneath sivler hair, gleams with mirth.

Imre Andrassy, the count, is older but he doesn't look it. He says he once was a man of immense wealth and influence in Hungary. He raced automobiles, flew planes and claims to have pressured all of Hungary during World War II into mixing alcohol with gasoline to conserve energy.

He wears sneakers nowadays and fell off the roof a while back. He's sprightly and he is mad as hell at Jimmy Carter for not proposing that alcohol be mixed with gasoline to get an immediate 10 per cent energy savings. But more about that later.

Before getting on with the tale of how the Andrassys lost their fortune and have adjusted to penury, it makes sense to explain just how important Stella Andrassy's solar reseach is.

Princeton University architecture professor and solar energy expert Harrison Fraker says of her and her work: "She is a pioneer, an incredibly creative and inventive person. She has based all her work on fundementally sound principles and has tried to promote them in a world that hasn't listened for nearly 30 years."

Fraker, who spent time last fall in sun-drenched Oman working with the government there on solar research, says Stella Andrassy's solar inventions - which include a solar oven, solar water heater, solar water purifier, solar sludge desiccator, solar desalinator and solar fruit dehydrator - represent "very good and workable designs."

Her inventions, Fraker says, constitute the state of the art in what is called "intermediate technology," which is suited so sunny, third-world countries that rely upon simple, inexpensive manufacturing methods.

Stella Andrassy's inventions are not the most highly refined or efficient devices yet invented, says Fraker, who has worked for the federal government as a consultant on similar devices. But she and her work are unique, Fraker says, because they continue to be guided by a deceptive simplicity.

Fraker discovered in Oman that simple ideas are the most workable. "The thing to do is to find not the highest technical solution, but the appropriate technology. If that is genius, than Stella Andrassy is a genius."

The Andrassys have failed, thus far, to make any money off genius because neither is interested in business. "We are scientists," Imre declares, arching his white tufted eyebrows. Fraker says that with proper marketing and promotion the Andrassys definitely could make money.

A company called Princeton Solar Corporation has recently been set up by a Princeton woman to market the Andrassys' inventions. Stella Andrassy, herself, after years of struggling with a fixed income, says, "I am now ready to make money off the sun."

Stella married Imre in Stockholm when she was 17. He was a Hungarian diplomat and highly decorated war hero from World War I. She was the daughter of a wealthy Swedish historian and nuseum curator. Together they went back to Hungary to what they describe as a 30-room mansion with 12 servants plus gardeners on a massive estate that included a private bacteriological laoboratory.

The mansion in Letenya, south of Budapest, was one of the Andrassys' smaller homes. According to Stella, the family owned more than 100,000 acres throughout Hungary, Imre's father was a member of what was then Hungary's Home of Lords. "You see," Imre says, "I was somebody back there."

In Hungary, according to Stella's resume, she did much more than have children and and live extravagantly. She studied piano at the prestigious Franz Liszt Music Academy, introduced to Hungary the Swedish system of fighting tuberculosis, brought a Swedish professor to their private laboratory and worked with him to develop a leprosy serum, organized an antimalaria station, founded a health-care center for infants and was publisher and editor of "Kincess Ujsag," a 200,000-circulation weekly magazine aimed at educating rural Hungary.

Stella Andrassy says Imre bought Hungary's second largest newspaper, which owned the magazine, so she could have a voice. The magazine, she recalls, sold for the same price as one egg. Imre published the newspaper.

This blaze of activity amid landed splendor ended abruptly when the Russians stormed across Hungary in 1945. The Andrassys, their three children and one grandchild fled to Austria, scaling the Alps in early spring riding seven horse-drawn wagons overloaded with funiture and paintings.

The journey, with Russian bombs falling around them and fleeing Germans looting their wagons, was hellish. Some days in the Alps, they moved just a mile with Imre hitching all the horses to one wagon at a time for steep grades.

All seven of their dogs starved to death; nine horses either starved or pulled until they dropped dead.

The Andrassys made it to Sweden where Stella spent the next two years writing a book about Hungary and their flight. It became a European best-seller, seven editions, translated into three languages. The money from the book was their only income.

In 1948, Stella came to New York City. Imre took off for nine years to South America to prospect for gold and coal. He made little money prospecting. In New York, meanwhile, she was asked to write a book about solar energy.

Dr. Maria Telkes, a solar researcher at New York University, had read Stella's book about the Hungarian flight. She wanted a simple-language explanation of solar energy devices. Stella Andrassy joined Dr. Telkes to begin research on the book and stayed on with her for eight years as a senior research aide. They worked, in particular, on solar distillation and solar ovens.

In 1959, the Solar Energy Laboratory at NYU was bought by Curtiss-Wright and moved to Princeton, Stella made the move too, and was joined by Imre, back from his unsuccessful South American Prospecting.

For Curtiss-Wright, Stella Andrassy helped perfect an oven that cooked meat so that it lost less than 10 per cent of its water weight. She was sent to Virginia to test it, cooking turkeys for a company called Dinner Ready. In one day, she recalls, she cooked 1,400 turkeys. "I was knee-deep in turkey fat."

The solar lab in Princeton closed in 1960. The Andrassys had nowhere to go, little money. They scaled down their lives, cut out the theater, along with most other outside entertainment and started their own research in their basement. They incorporated as Solar-Electric Laboratories. Imre is president; Stella, director of research.

Financing the research from Social Security and some savings, Stella Andrassy tinkered with and simplified solar devices she had worked on in New York. For example, the solar oven developed at NYU required the removal of 270 screws to replace a broken glass plate. She thought this ridiculous. She modified the oven - four screws must now be removed to change the glass.

With the financial assistance of Denys Reid, a Princeton woman who heads the borough's environmental commission (the same woman who has started the company to market the solar devices), Stella Andrassy developed a sludge desiccator. The device dries and pasteurizes sewage sludge with sunlight, while extracting and purifying water.

A model has been tested with sludge from Princeton's sewage treatment plant. It works well. Princeton University's Fraker says the sludge desiccator, which works on the simple distillation principle, is cost-effective and efficient.

"I have a hunch," Fraker says, "that it would stack up very well against any similar device."

Reid, a long-time friend of the Andrassy family, says of the inventor: "If she didn't have to bother with other things, she would be inventing night and day." Fraker says it is sad that the Andrassys haven't made money off the solar devices. He adds that now, with industry's rush to cornor the solar energy market, the Andrassys haven't much of a chance to "make money from the sun."

The press of finances and the loss of opportunity, howver, do not sadden the Andrassys.

Sitting in his living room on 200-year-old and increasingly thread-nare Swedish furniture, Imre explains: "Two-thirds of our lives we have had everything money could buy. Now we can be happy on nothing."

As an inventor who failed to mesh with American industry, Stell Andrassy says, "I was a quater of a century too early. The country didn't need my inventions before. Time has to ripen. Young people will pick up where I leave off."

Her inventions thrill her, even if they don't make her rich. The sludge desiccator delighted her: "When I first saw pure water come from that awful, smelly sludge, I nearly cried with joy."

She is not yet ready to leave her work to younger researchers. In the basement banned to visitors, she and Imre are working on a solar steam-creating device that is to be coupled with an electric generator.

The Andrassys are working to create devices for small houses to free poor people from the grip of utilty companies and rising prices. "It is immoral, almost criminal to charge old people so much for oil and electricity," Stella says. "But we cannot appeal the increases. They would just come and disconnect our service."

To pay the bills and to support research, she has sold the jewelry and some of the paintings she managed to haul out of Hungary.

Some artifacts of past wealth remain, including giant oil portraits of Hungarian royalty and a drawing of Imre's mother by renowned turn-of-the-century artist Philip Laszlo, who also dis portraits of Theodore Roosevelt, Benito Mussolini and Kaiser Wilhelm II.

The artifacts arouse curiosity, provoking questions that Imre refuses to answer. He refuses, also, to be photographed. He says he is afraid of Communist. In the late 1940s, Stella gave virulent anti-Communist testimony before congressional committees.

Imre says the past is gone. What he wants to talk about is gasoline and alcohol.

Imre, in 1974, ran his 1966 Dodge on a mixture of 10 per cent methanol and 90 per cent regular gasoline without any engine adjustements. He says the car ran well in the year-lon experiment, which was supervised by Stella, and produced a clean exhuast.

The Andrassys have devised a plan whereby each state can use its agricultural waste (Nebraska using spoiled grain; Washington, bad apples) to make distilled alcohol to be mixed with gasoline.

Neither Andrassy can understand why Carter and his energy people aren't interested. They prefer arguing about conservation to any talk of the past, of poverty or of marketing solar devices.

"You see," Imre says once again, plaining everything, "we are scientists."