AUGUSTA — Maine’s rooftop solar installers and the state’s major utilities have set aside their long-standing difference to strike a deal they say could increase solar power in the state tenfold in five years.

National solar installation firms are trying to stop it.

The Alliance for Solar Choice, a national group, and California-based Sunrun and SolarCity want to kill a key part of the plan as it moves through the Maine Legislature.

Autumn Proudlove, senior policy analyst at the North Carolina Clean Energy Technology Center, said Maine is getting this attention because lawmakers are considering a novel solution for a regulatory problem that more than a dozen states are also wrestling with.

The Maine plan addresses the contentious issue of “net metering,” a long-standing financial incentive used in Maine and other states.