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.

Ivan Frishberg, an environmental advocate and a member of Capitol Hill’s Advisory Neighborhood Commission, installed a $34,000 solar system on his home, only to be told that the city would not be able to reimburse him the $11,000 it had promised.

He said officials promised he would be on the list of those considered first for any new funding that becomes available next year.

“That’s not really a commitment,” Frishberg said. “Now they’re writing a second check they can’t keep.”

Solar installation companies also have been caught in the bind. Astrum Solar, an Annapolis-based firm, has installed more than 50 systems in the District and is working with another 50 people on the waiting list for D.C. funds. Most residents are reluctant to move forward, said Joshua Goldberg, Astrum’s vice president for policy and business development.

“We’d like to move away from grants, which are subject to budgets and legislation year to year,” Goldberg said.

To that end, the council is considering legislation designed to increase demand by requiring companies to use more renewable energy. They also want to make the energy credits obtained by homeowners who install systems more valuable by limiting the ability of companies to comply with renewable energy regulations by purchasing credits outside the city.

In the meantime, recognizing the likelihood of ongoing budget woes, Tulou and Cheh are considering a proposal that would slash in half the amount of grant money awarded in the solar energy incentive program next year. A public hearing on that proposal is scheduled for March 16 at 1200 First Street NE.

For Levy, the experience has made him think twice about trying to convince friends to purchase solar panels.

“It’s hard to make the pitch to anyone now,” he said. “I had lots of e-mails from friends about it, but now I’ve had to say, ‘Hold everything, I can’t recommend doing this anymore.’ ”