A letter from Chestertown, Md., makes reference to my comments about Vepco's new office building in Richmond, which operates during daylight hours on electricity made from the sun's rays. The letter says:

"Hey, Bill, didn't you see the TV program about a week ago telling of the big hospital just completed in New Mexico? By adding $2 million to the construction cost, they installed solar power and estimated they'd save enough in four or five years to get back the extra $2 million. Now the hospital administrator estimates the $2 million will be saved in only two years."

The letter adds, "Don't use my name, I'm no expert on this stuff, but how do you like what they have accomplished -- no thanks to the "Seven Sisters' who control the oil industry or to the Department of Energy. You know, Big Oil put off solar energy as long as possible because they hope nobody else will utilize it until they figure out a way to grab a monopoly on it."

I, too, am not an expert on Big Oil, but I have formed a somewhat different impression of the situation.

I agree that we have been too slow in solar research and in utilizing what we already know.

It is true that Big Oil has not been eager to see solar power replace oil, but this does not surprise me. When we begin transforming solar energy into vast amounts of cheap electricity, far fewer gold-plated Cadillacs will be bought by OPEC producers or by the American investors who have been refining and distributing their oil. One does not expect a businessman to favor a switch to a competitor's product.

As for the Department of Energy, it has indeed made some mistakes, but DOE has not been entirely without merit. It has finally begun to get its act together, and there is hope for the future, especially if President Carter and the Congress insist on better performance.

Before most of you were born, I saw a Broadway musical (I think it was called "Good News") that featured a song for lovers. The song's lyrics proclaimed that "the moon belongs to everyone; the best things in life are free." It could have made the same statement about the sun.

Nobody owns the sun or can get a monopoly it. However, the company that is first to develop an efficient technology for harnessing the sun's power may reap richer rewards than all the Seven Sisters combined. One company might even have a monopoly for a while. My guess is that several good techniques will emerge at approximately the same time, and therefore there will be no monopoly.

The problem is that somebody will have to risk billions of dollars to develop the new technology to its fullest, but sources of this kind of risk capital are extremely limited. The government can speed the development of solar power in several ways -- for example, through loans, tax credits, joint ventures and a favorable legislative climate. But so far our government has done little.

While we're criticizing the Seven Sisters for not putting all their profits into solar research, let's keep in mind that our government hasn't moved very fast, either. SWIFT COURIERS

At times, the Postal Service can make even DOE look good. Consider this report from Jerry Silver of Adelphi:

"I have received a card from Newsweek advising me that the Postal Service has returned several subscription copies as 'undeliverable.'

"I have lived at the same address for two years, and previously received Newsweek and other magazines regularly. The card that the USPS did deliver to tell me about the delivery problem was addressed exactly as my subscription address reads. Why did the USPS decide that the magazine is not a deliverable item?"

Perhaps it was because Newsweek reported what's been happening to the cost of living. Some people consider big percentage increases "obscene." THESE MODERN TIMES

I'm reminded of an observation in the current issue of Changing Times: "Some experts say higher prices will cut gasoline consumption, thereby easing some of our problems. Meanwhile, food prices may go high enough to end all our problems." HELP WANTED

Attention business executives: If your firm is giving out 1980 calendars, please divert a few to D. C. Village, Washington's home for the aged. William J. Jackson, chief of community activities there, tells me he has 200 requests for calendars from residents at the facility. You can reach Jackson by calling 767-7851. Thank you. ADD SIGNS

Buck Goings reports that a sign in the Super Garden Market in Arlington cautions: "Taste Makes Waist."