Massachusetts heads into the holiday season with some unfinished environmental business. Despite some late action with competing bills, the Legislature failed to raise the cap on a popular solar program before it wrapped up the 2015 session.

The state’s solar ceiling has already been reached in 171 communities serviced by National Grid, primarily in eastern Massachusetts. The limit doesn’t affect small residential solar projects. But the cap does prevent larger, often shared or community solar arrays, from powering their homes with remote solar arrays that benefit renters, low-income communities and homes whose roofs aren’t suitable for solar panels.

The cap applies to the net-metering program, which permits owners of solar arrays to sell excess electricity back to the electric grid for credit. Solar-energy advocates say the low cap is stalling proposed projects and dialing back the state’s growth in the solar sector.

“Here’s the bottom line: We should not put a limit on clean energy. Instead, we should move as quickly as possible to power our society with 100 percent clean, renewable energy — and solar will have a critical role to play,” said Ben Hellerstein, director of the environmental advocacy group Environment Massachusetts.

Supporters of lifting the cap include social-justice groups, religious leaders, academic groups and cooperative power developers. They argue that solar creates jobs, lessens price spikes by reducing peak demand, and reduces costs for affordable housing developments and food banks.

National Grid and the utility Eversource oppose legislation to raise the caps, claiming it will raise electric bills.

“We think solar energy can happen in Massachusetts without [raising the cap]. We think it adds unnecessary costs to our customers,” said Mary-Leah Assad, spokesperson for National Grid.

There is still strong public opinion in favor of subsidized solar energy in Massachusetts. According to Environment Massachusetts, the state has 391 solar companies that employ an estimated 12,000 workers. Massachusetts ranks fourth nationwide for the amount of solar capacity installed in 2014, and has the sixth highest total solar capacity in the nation.

The state also is on track to reach its goal of 1,600 megawatts of solar capacity by 2020. The net-metering limit for National Grid customers was reached in March.

Separate bills were passed by the House and Senate in the final days of the session, but neither bill advanced through both chambers. The legislation is expected to receive consideration when the Legislature resumes in January.

“When officials return to the Statehouse in January, we hope they make the expansion of solar power one of their first priorities,” Hellerstein said.

In August, Gov. Charlie Baker introduced a bill to raise the solar caps. Critics said his increase is too small and drastically cuts the compensation that entices cooperative and community solar projects.

Baker also introduced a controversial bill in July to bring Canadian hydropower to the region. Proponents of the hydropower bill say it diversifies the state’s energy mix with an energy that is cleaner than coal and natural gas. Opponents worry that hydro’s low cost will drive down demand for local renewable energy. Both of Baker’s bills are still in committee.