PORTLAND, Maine — Environmentalists and a trade group representing large power customers have asked Maine’s top court to review a controversial decision to dial back an incentive program for solar power installations at homes and businesses.

The Conservation Law Foundation, Natural Resources Council of Maine and Industrial Energy Consumers Group on Monday asked the Maine Supreme Judicial Court to review regulators’ decision to alter the state’s net metering program.

The net metering program allows solar power customers to receive credits on their electricity bills during times when they generate more power than they consume, putting that power back onto the grid. The home or business owner can then use those credits to pay for energy drawn from the grid at a later time, with the credits expiring at the end of each year.

The Maine Public Utilities Commission decided to scale back the program out of concern that the system is overcompensating solar power users. The current system pays homeowners credits worth the full value both of electricity and the unit cost of transmitting and distributing that power.

Starting in 2018, the commission’s ruling reduces the amount homeowners get in credits against their transmission and distribution costs.

The decision put the commission in the crossfire of solar advocates and Gov. Paul LePage, who called for all three commissioners to resign over the ruling as he argued that it causes other electricity customers to subsidize those with solar panels. Conversely, environmental groups and solar power advocates argued the ruling went too far for entirely opposite reasons.

In the appeal filed Monday, appellants argued to the court the commission’s ruling wasn’t supported by evidence in the case, did not follow state statutes seeking to encourage solar power adoption and did not properly assess the impact on small businesses.

They also argued the PUC overstepped its authority by making the change and that the new rules constitute “unjust discrimination” against certain customers.

The appellants had first asked the PUC to reconsider its decision, but regulators said they could not consider the request because it came after a deadline for filing such a request for review. The Conservation Law Foundation challenged the commission’s calculation of the deadline and has asked regulators to clarify their position.

“In the present case it would have been impossible for participants to meaningfully petition for reconsideration even had they done so one day after issuance of the commission’s order,” wrote CLF Executive Vice President Sean Mahoney.

The commission usually rules on reconsideration requests before appeals to the Maine Supreme Judicial Court, which handles appeals of PUC decisions directly.

The appeal also comes as solar advocates are gearing up for another fight in the Legislature over solar policy, after a compromise effort narrowly failed to clear LePage’s veto pen last year.

Solar advocates on Monday also took part in a social media campaign to call attention to the approximately 570 jobs in Maine’s solar industry, according to the Solar Foundation. Cumberland and Waldo county, where solar installer ReVision Energy’s two offices are located, topped the list for solar jobs by county.

The industry previously asked regulators not to alter the net metering program, saying that it would slow the young industry’s growth and stall a shift to more renewable energy.

Read the full appeal below.

Darren is a Portland-based reporter for the Bangor Daily News writing about the Maine economy and business. He's interested in putting economic data in context and finding the stories behind the numbers.