RICHARD Hibbert built his own Fairfax Station, Va., solar house in 15 months with help from his wife and children. When it got too dark to work, he went home and built a Heathkit television set. Hibbert got in practice to build the house by making all the furniture.

The biggest bonus is their utility bill. The all-electric/solar house costs $40 to run in the summer and a maximum of $150 for the two coldest months. Their utility bill for everything last year was less than $750. The house has 4,200 square feet of space - three bedrooms plus two big studio rooms under the eaves, a greenhouse, a two-level living room and dining area and a two-car garage. The house is an active solar house - the heat is collected by mechanical means. It is not a passive solar house because it has few windows to collect the sun. The house is rather dark, but cool in the summer.

The two-acre site cost them $22,000. The materials for the house, including all the solar equipment, was another $81,000. The Hibberts think it would sell for $200,000 (Though nobody intends to sell). They figure they got the house for half cost - and 15 months hard labor.

In Hibbert's job as an architect for the Navy (he's not the chief of its family housing), they lived in 18 different houses - including six years in Japan - during their 23 years of marriage. Finally, one day, after years of talking about building a house (with nobody paying much attention), Hibbert said, "This is it. Let's build it." And the rest of the family, with some trepidation, agreed. The Hibberts are pleasant, comfortable people, in their mid-40s.

Hibbert didn't do it on his own. Jennie Hibbert and their daughter Kerry, 16, dipped in stain every one of the cedar boards that surface the house. Their sons, Mike, 21, (now in the Navy), Chris (now at MIT) and Steve, 18, (working in a summer construction job) worked along with their father.

All survived, but two barely, because of icy ground. Hibbert's ladder slipped on an icy patch and he fell off the roof, 15 feet or so. He spent a week and a half in bed with a whiplash injury, thinking he got off lightly. Steve slipped twice on the ice while carrying loads, and broke both arms, one each time. They figured they put in about 70 hours a week on the house.

"I took my vacation leave by the house," said Hibbert, the other day, as he and his wife and daughter showed off their home while enthusiastically taking turns telling the family stories.

"I'd leave my office about 3 p.m., and work on the house until dark," he said.During the weekend, I'd start at 5 a.m. and work til sunset." They did hire the plumbing done and the sheetrock walls laid.

There was no water on the site, so Kerrie and her mother hauled it in in plastic milk jugs. When they weren't needed to help hoist panels or stain siding, they made the garden. The garden was laid out using a hose to make the pattern of rock and flower beds.

For about five or six years, Hibbert had been working with Navy housing on the possibility of solar heated houses. "I had this idea that solar houses didn't have to look strange and mechanical. I thought the solar panels could be handled in such a way that they'd work in with the design. And that's what I set out to do."

The house has a pleasant woodsy look to it. The solar collectors look almost slate colored so they actually blend in well with the exterior of the house. They cover almost all of the steeply slanting roof, which comes down quite far, only leaving room for the front door and garage doors. The rest of the facade is covered with panels made of real slate cast in concrete.

The Hibberts made those themselves as well. The fireplace wall in the living room's conversation pit is made the same way, as is another panel in the living room.

You come into the house through a low vestibule. To the right is the family entrance from the garage and the storeroom. To the left is the greenhouse, and a place for Hibbert's darkroom. The other day, when the Hibberts were showing two guests around, an uninvited guest was already visiting the greenhouse - a fierce looking black snake.

From the entrance hall (eventually there will be a second inside door to help conserve heat), you go up the stairs to the main floor. While in no way a Japanese house, it does have evidences of the Hibberts' six-year tour in Japan - the contrast of dark and light woods, the slate panels, and of course the dolls, the ceramic pots, the Japanese screens and other reminders of their stay.

The living room has acres of cabinets - many with tambours, built by Hibbert. A few steps down is the conversation pit, with built-in seating, the wide fireplace wall with log storage, and another cabinet with the Heathkit television set.

Up four steps is the dining room, separated from the kitchen by a ceramic tile counter. A deck is off the west side - a heat trip in early spring and late fall, shaded by tree cover in the summer.

To the east are the bedrooms and compartmented baths. Kerrie has the medium size bedroom, Steve the small one and the parents the big one with the bed headboard built like a Japanese gate. In their bath is a deep Japanese soaking tub.

The third floor has one section that's a balcony overlooking the living room and kitchen. Jennie Hibbert makes her macrame here - one especially nice macrame work screens a window in the living room. Hibbert has a corner with his drafting board built in here. After hours from the Navy, he designs houses for individuals. He's working now on an underground house and he prefers to specialize in solar and energy efficient designs.

The other end of the third floor is a big room used as a dormitory (with Japanese style pillow beds) when the boys come home, or whenever anyone would like a bit of seclusion.There's a bath up here as well.

The 750 square feet of solar panels cover almost all of the south side of the house. The steep (56 degree angle) roof comes down quite low, just leaving room for a front door and a garage door. Hibbert assembled the collectors himself, setting them into the frame of the roof.

The bottom part is Rollbond aluminum panels from Olin Brass. The top is tempered, textured, translucent high transmission glass made for solar collectors by American St. Globin. The edge is trimmed in redwood.

Oil (which doesn't freeze) runs through the panels and then through heat transfer equipment to four water tanks. The 4,000-gallon storage tank, a heat sink, is burried six feet below the house. A 1,500-gallon tank holds the day's collection. A 120-gallon tank is connected to the day tank. The smaller tank is for normal domestic hot water use. An electric coil boosts the heat in winter when the day tank water is used for space heating. A 40-gallon tank with another electric coil is a backup booster for heat on dark days in January and February. The hot water, so collected, serves as the heat source for the two water-to-air heat pumps.

In the summer, the heat exhausted by the cooling, is stored in the 4,000-gallon storage tank. Some of the heat leaks out into the earth in which it's buried, so the Hibberts start off their cooling season in November with a tank full of 115-degree hot water.

Hibbert used other devices to save energy. The north facing roof is built like an old ice house roof, hollow and so angled that the sun's heat will make a chimney effect in hot weather to drawy hot air up and out. In the winter, the hollow makes a heat pocket to help insulate the house.

Now that it's almost finished (except for the kitchen cabinet doors and a bit of trim here and there), the Hibberts think it was worth it. Though nobody would care to do it again. CAPTION: Pictures 1 through 3, The Hibberts' do-it-yourself home has solar panels on the roof (above left), Japanese art work (above right), and a conversation pit (left) where they can discuss future projects. By Douglas Chevalier - The Washington Post.; Picture 4, Jennie Hibbert in the kitchen, which has wood cabinets and ceramic counters. By Douglas Chevalier - The Washington Post