Georgetown University plans to build on a campus hillside what is believed to be the world's largest solar-electric building.

The $27-million intercultural center, with its 600-foot long roof steeply pitched to catch the sun's rays, is expected to provide nearly all the power to heat and light the six-story building and a 400-seat cultural theater to be built beside it.

The solar building, which will be invisible from nearby Georgetown because of its hillside setting, will be the third major campus structure designed to make the university largely self-sufficient in energy. Half the funds for the solar building are expected to come from the U.S. Department of Energy as a demonstration of advanced use of solar energy in large buildings.

Georgetown is now completing construction of two other energy-saving buildings and is considering putting new solar roofs on many existing campus buildings under the university's unique energy master plan.

This spring, Georgetown expects to dedicate.a $7.4-million underground sports center, which will need no air conditioning and little heating since the earth around it maintains a constant, year-round temperature of 61 degrees, and a new $14-million university heating plant.

The steam heating plant will be the nation's largest commercial test of a new, low-temperature coal firing process. The plant can be adapted to produce electricity. It will burn high-sulfur coal without visible coal piles, smoke stacks or air pollution, college officials said.

The historic hilltop campus, founded in 1789 as the nation's first Catholic university, now has more than $70 million in building projects underway.

Much of the recent construction, including residential townhouse "villages" for students, garages and a new campus road system, will make Georgetown more of a residential university and reduce the impact of its students and their cars on nearby Georgetown, said university planners.

Only 2,800 of its 10,000 students now live on the 100-acre campus. But an $8.4-million village under construction beside the school library soon will bring 504 additional students on campus. Another village for about 360 students is planned directly across from the main gate at 37th and O streets NW. Under proposed university traffic plans, the gate would be closed to most auto traffic and the main entrance transferred to Canal Road, a plan now under study by a consultant.

The major goal of all new construction, since 1973 and the Arab oil boycott, has been to reduce Georgetown's skyrocketing fuel bills. The university paid $700,000 in 1970 for heat and electricity, and more than $3.9 million last year, according to university architect Dean Price.

The new solar building project, which the last Congress authorized for federal funding, was officially submitted to the Department of Energy this week. The university hopes that when the building is completed in 1981 it will produce 480 to 600 kilowatts of electricity, or possibly more, since the efficiency of solar photovoltaic technology is improving rapidly, Price said. A product of the space program, the photovoltaic method translates sunlight directly into electricity.

The building will connect into the university's electrical system, with the blessing of the Potomac Electric Power Co., and ultimately -- when other campus buildings also are producing electricity -- could provide electricity to surrounding Georgetown in the event of an areawide power failure Price told the D.C. Fine Arts Commission last month. Although the building will not be seen from Georgetown streets, the federal commission is concerned about its visibility from across the Potomac on the George Washington Memorial Parkway. Price said last week the red brick building and its slate gray solar "shingles" will be visible from the parkway but should be less noticeable than any of the new campus buldings.

"It is not just the largest solar building of its kind but is an aesthetic and architectural solution... a handsome building in an historic district," Price said. Most existing large solar electric buildings are ugly, he said, "like the barracks at Fort Hood, Tex., which has acres of reflectors and concentrators."

The new intercultural building will have mostly glass and balconies on its north side and will resemble the Dulles International Airport, except that its roof will not be curved. It will be the main academic building for the Georgetown's 60-year-old School of Foreign Service as well as its School of Languages and Linguistics.

The U.S. Department of Energy will spend $118 million this year on solar electric projects and research, including design work on a 500-kilowatt photovoltaic project at Phoenix Airport in Arizona, according to Paul Maycock, director of the photovoltaics branch. Presently, the largest solar electric building is at a community college in Blytheville, Ark., which produces 250 kilowatts.

The Georgetown building will be designed to be an all-electric building but also will be connected to the campus steam-heating system and plugged into the general electrical grid. Under the energy master plan, the campus may well become all-electric in the longrun, perhaps with most of its buildings refitted with solar electric roofs. The coal-burning heating plant, which replaces the present natural gas and fuel oil plant, will someday itself become only a back-up system, Price said.

The coal plant is a "co-generation" plant since it can produce steam for heating as well as for conversion to electricity. It is the largest of five federally funded industrial projects designed to demonstrate the reliability of the "fluidized bed" method of burning high-sulfur coal, which has been tested successfully since 1967 at a small model power plant on Alexandria's waterfront. High sulfur coal normally would be considered unusable in an urban area because of sulfur and nitrogen pollutants.

In the process, compressed air is forced through thin layers of limestone and coal, which is burned at low temperatures, producing fewer pollutants than high-temperature combustion, according to Energy Department officials. The air then passes through a giant vacuum cleaner bag and comes out well within the District's strict air pollution standards, energy officials said.

While the Georgetown coal plant will be America's largest commercial-industrial test of the process, several small plants are being built at federal installations -- such as the Great Lakes Naval Research Station -- and a large facility already is using the process at a power plant in Reesville, W. Va.

For a small urban campus, however, both the heating plant and the solar electric building will be unique, and perhaps the heating wave of the future. Georgetown envisions a day, possibly even within the next decade, when it will be self-sufficient in energy, a sort of campus space capsule on Georgetown's hill. CAPTION: Picture 1, Model of the proposed $27-million intercultural center.; Picture 2, Site of the proposed solar building on Georgetown's campus. In the background, behind the trees, is Copely Hall. By Craig Herndon -- The Washington Post