A panel of experts says a new national health plan, based on marketplace competition and designed by Stanford University expert Alain Enthoven, would cost less and serve the public better than the comprehensive plans proposed by President Carter and Sen. Edward M. Kennedy (D-Mass.).

The panel, which included Enthoven, a former Pentagon "whiz kid," sets out its conclusions in a book called "New Directions in Public Health Care," published by the nonprofit Institute for Contemporary Studies, a San Francisco think tank.

UCLA professor Cotton Lindsay, who wrote part of the book and edited it, said studies of national health insurance in Canada and Britain and of some government programs in the United States indicate that a comprehensive national program here would mean "truly staggering" cost escalation, waste and increasing government control.

He said there is little evidence that people in Canada and Britain are in better health as a result of national programs than if alternative health systems were in effect -- but the cost is greater and controls and waiting lines for treatment, far greater.

Enthoven said a major reason for cost-escalation here is that health-insurance plans -- usually obtained through an employer -- don't foster competition between hospitals or doctors to hold costs down, and usually the employe hasn't any choice of plans.

He proposed giving everyone in the country a basic government payment, in the form of a refundable tax credit, to buy health insurance. Employers would be required to offer employes a choice of several plans, all meeting at least minimum benefit standards set by the government.

Recipients would tend to use their government payments to buy the plan that offered the most for the least money. The plans would thus have to compete against one another in efficiency.

In the case of a group health association (HMO), its own doctors and hospitals and administrators would be able to control costs, fees and purchases directly in order to hold costs down.

In the case of a plan in which you choose your own doctor and the insurance company pays part of his fees, Enthoven said, the companies would be impelled by the competition to pressure doctors and hospitals to hold costs down -- or even sign them up to work at fixed fees.

The key to the whole scheme, Enthoven said, is giving each person a range of plans, so that he can choose the one that offers the most value. This would foster cost-competition. Universal coverage would be achieved by making everyone eligible for the tax credit.

In addition to paying a large part of the initial costs of an illness, the basic plan would protect the insured against added "catastrophic" costs exceeding perhaps $1,000 a year. (The poor would get extra subsidies to cover this $1,000.)

He gave this illustration: Suppose the government credit is $60 a month. An employer would offer workers Plan A, Which costs perhaps $100 in premiums and contains only the basic protection package; Plan B, with somewhat richer benefits but costing $120; Plan C, even richer but $125. The worker would decide which is the best value for him.

Enthoven said plans like this are already working in Oregon, Hawaii and several other locales. Rep. Al Ullman (D-Ore.), chairman of the House Ways and Means Committee, has introduced a version of it in Congress, but President Carter opted against it when he drew up his own national health proposals.