Until recently a federal tax credit for solar panels was scheduled to be reduced, then go away in 2022.

That’s changed.

Congress extended by two years the 26% tax credit, which significantly lowers the cost of an individual solar investment.

The tax credit means the final cost for a $20,000 system is $15,000; $18,500 for a $25,000 system.

“That tax credit is pretty meaningful, more than a quarter of the value,” said Dan Burgess, director of the Governor’s Energy Office in Augusta. “Looking at the long-term opportunities, it’s pretty helpful.”

The costs vs. savings varies by system and building. Over a 25-year period, projections often show savings are in the thousands of dollars.

Other advantages are several, Burgess said. For instance, solar also provides a boost to the local economy.

More than $4 billion is spent a year in Maine on energy, Burgess said. Unlike oil and gas produced out of state, “solar is a local energy resource, a great opportunity for the state” to create energy and jobs, he said.

Another way solar helps everyone, said David Costello of the Natural Resource Council of Maine, is lowering the demand for electricity in the summer.

During the summer’s long hours of sunlight, solar provides more electricity to the New England power grid when there’s a spike in demand from heat waves.

“It shaves that higher cost peak,” Costello said. “It lowers the demand on the existing (generation) infrastructure. It helps take the load off at critical times.”