BOSTON — While sunshine is free, the future of a key solar power bill remains cloudy on Beacon Hill.

House and Senate lawmakers ended their formal sessions for the year without reaching a key deal to raise caps on the state’s “net metering” program that allows electric customers and local governments to sell excess solar power they generate back to the electrical grid in exchange for credit.

The Senate passed legislation earlier in the year to raise the caps to help the state reach its goal of 1,600 megawatts of installed solar capacity by 2020. That’s enough to power about 240,000 homes each year.

House lawmakers waited until Tuesday – the second-to-last day of formal sessions – before passing their own version of the bill.

Like the Senate, the House called for a 2 percent increase in net metering caps, but the chambers disagreed on several other provisions.

Lawmakers left for holiday break without getting final legislation to Gov. Charlie Baker’s desk.


Baker had urged action on raising the caps, pointing out that a federal solar energy tax credit program runs out at the end of 2016.

Baker also wants to raise the private and public net metering caps 2 percentage points each.

Critics say the Legislature’s inability to get a final bill approved could end up jeopardizing proposed solar projects already in the development pipeline that are relying on the net metering benefits.

Renewable energy advocates say 171 communities have already reached the cap, including those in much of eastern Massachusetts served by National Grid.

Baker has said even without changes to the net metering cap, however, the state is on track to hit the 1,600 megawatt goal by 2018 – two years early.

While individual homeowners are exempt from the caps, the inability of lawmakers to raise them is making it harder for larger projects and residents of apartment buildings to benefit from the program, advocates said.

The cap is calculated as a percentage of each company’s highest historical peak load – the most electricity consumed by their customers at any one time. Private facilities are currently capped at 4 percent, public facilities at 5 percent.

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