HALLOWELL — The Passamaquoddy Tribe can move ahead with a plan to install hundreds of solar panels on homes and administrative buildings in Indian Township, regulators unanimously said Tuesday.

The tribe has said the plan could save residents of Indian Township, where the per-capita income is about a third of the statewide average, more than $7 million over the next 25 years. But a dispute over whether it adheres to Maine’s net energy billing rules put the project on ice for more than a year.

At its core, the fight has revolved around whether the Eastern Maine Electric Cooperative should be required to provide billing credits for households that get rooftop panels installed as part of the project and produce more electricity than they use. That answer relies largely on whether the installations are viewed as one large project, as the co-op has contended, or as hundreds of smaller projects, as the tribe has said.

At the Public Utilities Commission’smeeting Tuesday, commissioners ruled that the project is in line with the original intent of the state’s net energy billing laws, and they said its shared funding source did not make the entire development a single project. The commission will issue a final written order in the coming days, which will also include guidelines for a possible appeal by the co-op, PUC spokesperson Susan Faloon said.

In a written statement issued after the meeting, the Eastern Maine Electric Cooperative said it was “disappointed” by the outcome of the PUC meeting and would review that final order to determine its next steps.

“To be clear, the Co-op is supportive of its members installing solar but is opposed to requiring its members to subsidize large solar projects that do not meet the Net Energy Billing program’s legal requirements,” the co-op said. For months, it has maintained that the project would violate the state’s energy credit rules.

With approval from the commission, the project’s fate is now largely up to the Environmental Protection Agency — and whether it will still allow the tribe to access a $7.4 million grant secured more than 13 months ago.

The commission’s decision comes as the federal government attempts to roll back renewable energy projects, including through the sudden terminations of already-pledged grants. This summer, the EPA clawed back a $62 million grant to install solar panels in low-income communities.

“We will probably — unless we get told otherwise by EPA — start to go ahead with purchasing materials,” said Trevor White, an environmental officer for the tribe who has helped shepherd the proposal since its inception. “The ball is in EPA’s court. They’re the ones who will tell me whether it’s okay to go ahead and draw down on this grant.”

So far, workers at the federal agency have told White that the funding should remain available, but they have not made any promises in writing, he told the Press Herald.

“I’m not sure anyone, frankly, has clarity on what the next move with the federal government and these kinds of funds is,” said Rebecca Schultz, senior advocate for climate and clean energy at the Natural Resources Council of Maine.

This story will be updated.