Even though it will ultimately have to spend two and a half times as much as it will save, Virginia Electric and Power Co. has decided to delay a major construction project to "save money."

Vepco announced yesterday it is stalling for a year completion of its billion-dollar Bath County hydroelectric power storage project.

About 300 of the 3,500 workers on the Southern Virginia project will be laid off and the completion date will be moved back from 1982 to 1983, said Vepco vice president S. C. Brown, Jr., who is in charge of power plant construction.

In an announcement, Brown said Vepco was "forced" to delay the project because of a series of financial problems "have severely reduced the money we have available for construction."

Slowing down work on the Bath County project will save Vepco $40 million in construction costs this year, said spokesman Thomas E. Stenzel.

But the delay will end up costing Vepco -- and the Virginia consumers who get their electricity from Vepco -- an additional $100 million, Stenzel said.

The $100 million includes the interest cost on the nearly $900 million Vepco has tied up in the project and the effect of a year's inflation on the final construction bill.

"You're trimming something out of the budget and it will come back to haunt you," commented Stenzel.

The extra $100 million will be passed on to consumers in 1983 when the plant is completed and generating power.

Vepco officials said the delay also will cost consumers additional money in 1982. Electric generating costs are expected to go down when the Bath County project is completed, but now those benefits will not come as soon as expected.

The precise impact of the delay on utility bills could not be calculated yesterday. On New Year's Day, an 11.8 percent hike in the amount Vepco charges its customers for fuel went into effect. That increase is expected to boost the average monthly bill for 1,000 kilowatts of power from the $55.89 to $62.43.

Even though the Bath County delays will cost consumers money, Vepco's decision was endorsed by Randy Phillips, research director of the Consumer Congress of Virginia.

"In spite of the extra $100 million, the delay will be good for consumers," he said. "It will help solve the company's cash flow problem," which Vepco officials claim makes it necessary to raise rates.

Vepco has had cash problems for many months because all three of its nuclear power plants are temporarily shut down. The company has been forced to use less efficient oil and coal burning plants to generate power and to pay soaring prices for oil.

The Bath County project that is being delayed consists of a pair of large lakes, one several hundred feet higher than the other.

When Vepco needs electricity -- mostly during the daytime -- water will flow from the upper lake to the lower lake through a turbine that generates power.

At times when Vepco has power to spare from its other generating plants -- usually after dark -- that power will be used to pump water from the lower lake back to the upper lake, so it can be used to make electricity again the following day.

The advantage of the pumped storage project is that it gives Vepco additional generating capacity during peak periods of electrical demand.

Vepco officials said the chief reason for delaying the project was finances, but admitted the company will probably not need the extra power generating capacity in 1982 anyway.

The spokesmen said the delays will not effect Vepco's negotiations over selling part of the Bath County project to some other utilities.