Giant Food Inc. reported yesterday that profits for the year ended Feb. 24 increased nearly 18 percent-a gain substantially higher than had been forecast in recent weeks.

Chessie Systems Inc., a large regional railroad holding company, said that its first-quarter operations produced earnings of $8.3 million compared with a steep loss in the 1978 period, when business fell sharply because of a coal strike and severe winter weather.

Giant, one of the two major food chains operating in metropolitan Washington, said unaudited results for the recent year show profits of17 million ($5.09 a share) compared with $13.6 million ($4.14) a year earlier.

Sales of the retail firm rose 15 1/2 percent to $1.08 billion. Both the sales and earnings figures are records for the Landover-based company, which recently embarked on a program of converting all of its non-automated checkout stands to the electronic scanning systems, at a rate of two stores per week through August.

Chairman Israel Cohen said full details on Giant's Fiscal year will be released in about 10 days.

Chessie System, owner of the Baltimore & Ohio, Chesapeake & Ohio and Western Maryland railroads, listed first-quarter earnings of $8.3 million (42 cents a share) compared with a loss in the 1978 period of $67 million Revenues rose to $400 million from $255 million.

"The first-quarter improvement was achieved despite seasonably low production levels, weather-related problems which affected railroad operations and a slack demand for coal in January and February," Chessie Chairman Hays Watkins said.

Revenues rose to "healthy levels" by the end of the quarter and "we look for a continuation of the good traffic levels" during the current quarter, he added. Revenues and profits should show "substantial improvements over the 1978 period, when May and June set earnings records," the Chessie chief stated.

Baltimore Gas & Electric Co. reported earnings of $21.5 million (69 cents a share) for the first two months of 1979, down from $23.5 million (77 cents) in the same period last year.

Implementation of a two-tier rate structure in January, which will result in somewhat lower winter revenues and higher revenues during the summer, was a major factor in the lower earnings. On an annual basis, earnings and sales should not be affected, the Baltimore utility stated.

in another accounting change ordered by the Maryland Public Service Commission, BG&E will file revised electric rates this week that will reduce revenues by $12.5 million. An average residential customer using 580 kilowatt-hours a month will have monthly bills cut by 57 cents.

The lower rates are the result of a PSC decision requiring the company to begin capitalizing its allowance for funds used during construction of an Anne Arundel County power plant at a 100 percent level compared with 50 percent used previously.

Solon Automated Services, a Washington supplier of laundry equipment services and owner of the Sugarbush skiing center in Vermont, reported higher earnings for the first fiscal quarter ended Dec. 31. Profits rose to $1.35 million (43 cents a share) from $1.2 million (39 cents) as sales increased to $15.9 million from $13.5 million. CAPTION: Graph, The Washington Post