It isn't easy going green, and it may also prove costly.

Dozens of District residents who installed solar panels on their homes under a government grant program promoting renewable energy have been told they will not be reimbursed thousands of dollars as promised because the funds were diverted to help close a citywide budget gap.

In all, the city has reneged on a commitment of about $700,000 to 51 residents, according to the D.C. Department of the Environment. The agency has pledged to try to find money in next year's budget, its director, Christophe Tulou, said.

"It just doesn't seem fair to go through a process with them and have them make investments in solar panels under the assumption they would be reimbursed," Tulou acknowledged. "It's really sad we are having these economic woes when we are."

The abrupt suspension of the city's Renewable Energy Incentive Plan, an annual $2 million fund that was supposed to last through fiscal 2012, threatens to dampen budding enthusiasm for clean energy among homeowners. The program has helped 315 people install solar panels, with another 417 on a waiting list that has been closed by city officials.

D.C. Council member Mary M. Cheh (D-Ward 3), who is leading the push for a sustainable energy utility to encourage green energy in the District, said officials are scouring the environment agency's budget in hopes of finding reimbursement money for the 51 homeowners this year.

But, she said, "I would think people would take a cautious approach" to future installations.

The District established its incentive program in 2009, joining a growing renewable energy movement among states and the federal government. The D.C. program is funded by a dedicated tax on city residents' and businesses' gas and electric bills. The fund reimburses participants about a third, and sometimes more, of the cost of their solar energy systems.

As budget deficits have soared, however, states have been scaling back their incentives or eliminating them entirely. In December, the D.C. Council voted to approve an emergency funding bill that closed a projected $188 million citywide budget gap by cutting social services and furloughing some city workers for four days. The $700,000 from the renewable energy fund was reallocated to other needs, officials said.

That came as a shock to Brian Levy, 35, who received a letter from Tulou on Jan. 25 informing him that the city would be unable to pay him the $12,200 it had promised last September. In October, Levy had hired a contractor, Green Brilliance, to install a $27,500 solar energy system on the roof of his row house on Florida Avenue in Northwest. The work was completed in December.

"I'm not ready to throw a Molotov cocktail at the D.C. government, but I'm very disappointed," Levy said. That money "is my backup fund I use in case of sickness, my safety fund."

Solar energy proponents banded together to create a network called DCSun, whose e-mail listserv has included missives from frustrated members.