In Connecticut, residential electric rates rose up to 27 percent last year to an average of $128 a month, and are expected to go up as much as 50 percent more in January.

In New Jersey, rates rose up to 13 percent this year, and are poised to go much higher.

New York residential customers, by contrast, paid an inflation-adjusted average of 16 percent less in 2004 than in 1996, a state report said. It is not known how much of that is attributable to government-ordered rate cuts, but the state benefited from huge increases in power generated by its nuclear plants and by buying power from New England plants that, starting next year, may have less electricity to sell to New York.

The Federal Energy Regulatory Commission and five other agencies, in the draft of the report to Congress, are unable to specify any overall savings. “It has been difficult,” the report states, “to determine whether retail prices” in the states that opened to competition “are higher or lower than they otherwise would have been” under the old system.

Joseph T. Kelliher, the commission chairman, said Friday that eventually “market discipline will deliver the best prices” and noted that every administration and Congress since 1978 had pushed the industry toward competition. He added that the commission recognized a need for “constant reform of the rules.”

Under the old system, regulated utilities generated electricity and distributed it to customers. Under the new system, many regulated utilities only deliver power, which they buy from competing producers whose prices are not regulated. For example, Consolidated Edison, which serves the New York City area, once produced almost all the power it delivered; now it must buy virtually all its electricity from companies that bought its power plants and from other independent generators.

The goal is for producers to compete to offer electricity at the lowest price, savings customers money.

Independent power producers, free-market economists and the Clinton Administration cheered in 1996 when the federal government allowed states to adopt the new system. The new rules “will benefit the industry and consumers to the tune of billions of dollars every year,” Elizabeth A. Moler, then chairwoman of FERC, said at the time. She said the new rules would “accelerate competition and bring lower prices and more choices to energy customers.”