The Washington Gas Light Co. has installed solar heating systems in two houses in this area as an experiment in supplementing gas heating.

"Solar energy can extend the life of depletable resources, like gas, and contribute to more efficient use of all fossil fuels," said WGL Vice President J.K. Hughitt.

One General Electric Co. solar unit has been installed in the College Park home of a gas company employe. The other has been placed in a new town house in Annandale. Both systems are expected to supplement conventional gas space heating and domestic water heaters.

"Our objective is to experiment with new and existing structures that are found in the metropolitan area," said Hughitt. "Additional units, including commercial applications, will be put into operation later this year."

He said that because the GE system is a package unit, it should minimize engineering and labor costs in installations made when the system is available commercially.

Hughitt said the 4-by-4-foot solar collector panels have 10 tubes that are modified versions of conventional GE fluorescent lamp tubes. Each tube consists of two glass cylinders. Sun energy enters the outer cylinder and is absorbed by the inner tube, which passes the energy to a sheet of copper.

Then the energy is transferred via a solution of anti-freeze and distilled water and circulated in copper pipes to provide heat in tanks for domestic hot water heating and another for storage of energy provide to a hydronic coil in a conventional hot air furnace.