To keep the lights on in her residential mental health clinic outside of San Juan, Liomarie Oyola Pérez needs money.

Ms. Oyola Pérez and her staff already go to extraordinary lengths during the blackouts that have become increasingly common in Puerto Rico, juggling three generators or waiting hours in line to get gas to power them. Her facility has solar panels, but she wants to add batteries that would store energy for use when the sun isn’t shining. For that, she needs a loan.

This year, her lender was awarded millions through a federal program that would provide low-interest loans to candidates like Ms. Oyola Pérez.

But the money is frozen, part of $20 billion committed to finance climate and clean energy projects that was abruptly halted at the request of the Trump administration. Several nonprofit groups that were promised funds have sued; a court hearing is scheduled for Monday.

At stake is funding for projects across the United States meant to assist people like Ms. Oyola Pérez and reduce their energy costs while also cutting the pollution that is driving climate change. They range from efforts to add geothermal energy to affordable housing in Iowa to energy efficiency upgrades for a senior housing community in Massachusetts.

Nationwide, the federal program could finance enough new solar arrays to power up to 2.2 million homes by 2031, according to a recent analysis from Energy Innovation, a research organization, and the University of New Hampshire.

For months, the Environmental Protection Agency has been trying to claw back the money, which had been authorized by Congress under the 2022 Inflation Reduction Act during the Biden administration. Since taking office, Lee Zeldin, the agency’s administrator, has repeatedly called the money a “green slush fund” and said it was vulnerable to waste, fraud, and abuse, though the agency has failed to produce evidence backing up those claims, despite a judge’s request. On the ground in Puerto Rico, 38 credit unions are waiting for $147 million committed under the program, which is known as the Greenhouse Gas Reduction Fund. They estimate it would support 88,000 solar, electric-vehicle and energy efficiency projects by 2030.

Contrary to Mr. Zeldin’s claims, these loans are vetted, supplemented by private capital and, for many recipients, are simply about keeping the lights on.

When the electricity flickers off inside a mental health clinic run by Ms. Oyola Pérez, the staff follow a protocol: First, they wait two hours to see if the power comes back. Then, they fire up a gas-powered generator, then a second, then a third. If the outage persists, someone has to go wait in line for more gas, sometimes for hours.

Inside the cheerful single-story building, where 22 residents include her aunt, her 106-year-old grandmother, and a shot-putter who competed in the 2023 Berlin Special Olympics, Ms. Oyola Pérez was clear about her long-term goal for avoiding blackouts.

“The plan is to stay off the grid,” she said. Leaving the island’s notoriously rickety electric grid is the dream for many in Puerto Rico. Two large-scale blackouts have hit the island in the last six months, and the average resident lost power eight times last year. After Hurricane Maria in 2017, many homes were without electricity for months.

Even without the threat of storms, local officials have warned that the power supply will not be sufficient to meet peak demand this summer. At the same time, Puerto Ricans have the fourth-highest electricity costs in the nation. The E.P.A. declined to comment for this article, citing a policy against discussing pending litigation.

But the power outages haven’t stopped.