PORTLAND, Maine — Solar installers and their allies are asking state utilities regulators not to tinker with incentives that have helped Maine keep pace with other states for growth in solar capacity, as the cost of solar panels continues to fall.

Thursday’s release of a petition to the Maine Public Utilities Commission from solar installers, businesses, faith groups and others comes after the Legislature narrowly sustained Gov. Paul LePage’s veto of a bill that would have shifted the state away from the current incentive system, called net metering.

For a home with solar panels, net metering allows a customer to receive credits equal to the retail price of power for times when their system generates more power than it uses, sending electricity back onto the grid.

In the absence of a more dynamic way to compensate small solar generators — something more similar to how other power generators in the region get paid — solar advocates have asked the commission to leave net metering in place, especially for existing customers, to avoid turbulence in the industry.

“The Nevada PUC’s unprecedented and unique move to make retroactive changes sent shock waves through solar markets,” the group wrote in a petition filed with regulators by Tony Giambro, co-owner of the Paris AutoBarn. “Even though that decision is now being reconsidered, significant harm has already occurred, from proliferation of consumer lawsuits to major layoffs.”

Major national solar installers that lobbied against Maine’s solar proposal, such as SunRun and SolarCity, ceased operations in Nevada after the change and laid off more than 600 people, according to the trade publication UtilityDive.

The group wrote to the PUC that it seeks to clarify that regulators won’t change net metering for existing customers, a group of about 2,245 customers as of the end of 2015, according to reports from the state’s two major utilities.

Under net metering, the residential solar market in Maine has kept pace with solar growth in other states, but it has lagged behind the rest of the Northeast, where all but Rhode Island has more installed solar capacity and almost all other states have had solar capacity grow at a faster rate.

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In March, figures from the U.S. Energy Information Administration show that Maine’s residential solar capacity had grown about 50 percent from one year earlier, hitting almost 10 megawatts of installed capacity. That’s about double the total in March 2014.

The rules governing net metering allowed utilities to ask for a review of that policy once solar capacity hit 1 percent of annual electricity consumption. Central Maine Power Co. asked for such a review in January.

As that request from CMP was filed and lawmakers deliberated a successor to net metering, Maine’s solar capacity growth continued.

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Solar advocates said that limit is lower than in other states and that regulators should not be deterred from allowing that percentage to rise.

“No other state in the Northeast has a cap on or trigger for reviewing net metering at such a low penetration level,” the petition states. “The commission review should take this into account.”

Advocates wrote the commission should keep its review of net metering limited to narrow questions about the policy, until lawmakers can again take up the issue of what comes next, using some of the analysis from a group of various stakeholders that fueled last session’s failed proposal.

“The Legislature has not asked the commission to propose a comprehensive solution or framework for distributed solar,” the group wrote. “We know the Legislature is quite capable of making that request because they did so in calling for the stakeholder process. The fruits of that process remain available for policymakers to consider again next session.”

The group of petitioners to the PUC included owners of Sundog Solar in Searsport, Insource Renewables in Pittsfield, ReVision Energy in Portland and Liberty, companies such as Allagash Brewing, the Mt. Abram ski area, and other groups such as the Union of Concerned Scientists, the Conservation Law Foundation and the Sierra Club of Maine.

Darren Fishell

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.