The future of solar power in Maine is once again up for grabs in the state Legislature. And powerful interests from Maine and around the country are trying to shape the outcome.

Fortunat Mueller is not a fan of a decision on solar energy that the Maine Public Utilities Commission made earlier this year. “It’s expensive, it’s largely unworkable and it’s probably illegal.”

Mueller, one of the founding partners of the Maine-based solar company ReVision energy, is referring to the PUC’s decision to phase out credits given to residential customers who sell solar-generated electricity back to the power grid.

The commission devised a new system it said would free consumers who do not have solar power from subsidizing those who do, but would still help homeowners recoup upfront investments in solar arrays, which are getting cheaper every year.

Critics, including Mueller, want lawmakers to nullify the regulators’ plan, before it goes into effect next year. “So it’ll be challenged in court even it does survive. So what we’re asking the Legislature to do is not let this rule go into effect.”

Mueller’s company started in a garage 15 years ago and now employs 170 people in three states. He’s supporting a measure that would keep the credit system that’s fostered that growth – called “net metering” or “net energy billing” – until at least 2021.

He says ending net metering without a more forward-looking and data-driven replacement would be a costly gift to the state’s utilities, which are prospering from new construction of bulk transmission systems paid for by consumers. Those infrastructure investments grow less necessary, he says, as more and more “distributed generation” sources, such as local solar arrays, take pressure off the grid.

“If your first goal is to protect utility profits, then you don’t want to lower utility and transmission costs, because those are utility profits,” Mueller says.

Mueller’s just one of the antagonists in a multi-party showdown over the bill, which also involves environmental advocates, industrial and residential consumer representatives, and the transmission and distribution utilities.

“Net metering today favors the business model of the large solar installers,” says John Carroll, spokesman for Central Maine Power, the state’s largest transmission and distribution utility.

CMP wants to end what it calls a cost-shift net metering creates by letting solar users off the hook for some of the expense of maintaining the poles and wires they depend on. With the amount of solar power doubling every two years in Maine’s energy mix, he says, the burden on ratepayers – and the windfall for solar power generators — could quickly rise to tens of millions of dollars.

He says the stakes are reflected by energetic lobbying in Augusta. “This is really an amazing exercise of muscle,” Carroll says. “To their credit people who have solar believe in it passionately, and they have an army of 3,000 people-plus who advocate for this. We have 620,000 customers, and absent those 3,000, they are not passionate about something they don’t see or don’t feel, directly.”

CMP is a power-player, to be sure, with a coterie of lobbyists working the issue inside the State House. And their effort to kill net metering does have outside support: A utility trade group called the Edison Electric Institute is targeting lawmakers with a social media campaign opposing the bill, and another group with roots in the fossil fuel industry, called the Consumer’s Energy Alliance, took out full-page newspaper ads against the bill last week.

On the other side, many of the state’s big industrial energy customers are opposing the utilities, saying that solar and other distributed power sources can slow escalating bills for transmission infrastructure. And solar installers such as ReVision and Sun Run, the nation’s biggest rooftop solar company, have formed a new lobbying group which is running radio ads in Maine to support net metering’s survival.

“This is the first bill that I’ve ever had advertised on the radio,” says Sen. Tom Saviello, the Wilton independent who introduced the original version of the bill. Saviello says he’s a bit surprised at the intensity of the campaigns it’s triggered.

“I don’t consider it a power play,” he says. “I just consider it as kind of a little bit bigger than a baby step but a step towards recognizing solar as being important in the state.”

The bill has morphed considerably since Saviello first wrote it – with committee members sending two competing measures to the full Legislature. Both versions, however, would undo a PUC decision requiring new meters to measure the output of every solar facility in the state, including output that’s used only on-site. That’s broadly seen as a costly and undue governmental intrusion on private property.

With so many interests working the bill, it’s difficult to predict which, if any, version will make it through the Legislature, and what might survive the governor’s veto pen. The bill could be debated as early as Friday.

If nothing new is enacted, protracted legal fights over the regulators’ solar power proposal, and continued uncertainty about Maine’s solar marketplace, will be the likely result.

This article appears through a media partnership with Maine Public.