Let the sun shine in.

Gov. John Baldacci celebrated Earth Day in Augusta this morning by using electricity in the now solar-powered State House. On Thursday, Baldacci assisted in the installation of a single solar array on the State House lawn. While the system isn’t hard-wired into the governor’s office, the panels will produce approximately 720 kilowatt-hours per year – or just about enough to equal Baldacci’s personal power needs, a fraction of the state’s total energy budget.

Naoto Inoue, managing partner of the Arundel company that built the array, called the new equipment a “symbolic reminder” of state government’s commitment to solar power.

Baldacci called on Maine residents and his fellow governors to install similar systems.

“It’s so compelling this year with the high costs of energy and the negative impact that has had on our economy,” Baldacci said. “We’re trying to recognize that being kind to the environment is actually kind to the budgets.”

The state has no plan to install additional solar panels at state buildings in the near future, said the governor’s spokesman, Lynn Kippax. The system installed Thursday was purchased with donations from environmentally minded Mainers.

“The desire is there. The money is not,” Kippax said.

Later this spring, however, legislators will consider a bill that, with the governor’s backing, would offer incentives for homeowners to go solar.

The bill, sponsored by Rep. John Brautigam, D-Falmouth, would offer a rebate of $3 per watt of solar energy on the first 2,000 watts and a rebate of $1 per watt on the next 900 watts, as well as a sales tax exemption. The bill also would create income tax credits for the purchase of photovoltaic cells and solar water heaters up to 25 percent of the system’s cost, or $500, whichever is less.

The total value of the incentives could reach between a quarter and a third of a system’s total cost, depending on its size and price, according to the state Office of Energy Independence and Security.

“The sun is coming down all around us, delivered free to our doors … and it’s going to be there forever,” Brautigam said, theatrically donning sunglasses “because the future of solar power is so bright.”

The freshman legislator installed solar panels at his family’s camp on Moosehead Lake four years ago. Brautigam has a backup generator, but since going solar, he has been driven to increase his energy efficiency.

“I get such a kick out of looking at the little meter on a sunny day,” he said. “It becomes a challenge – to get as little as you can from other sources.”

For much of the past 30 years, solar power systems have cost tens of thousands of dollars to install, because so many panels and storage batteries were needed to supply a typical household.

Over the past 10 years, however, Maine and 39 other states have passed laws allowing hybrid systems, in which homeowners produce some solar or wind power, but remain tied to the electricity grid. On a cloudy day, the solar hybrid household buys its power. On a sunny day, the excess power is uploaded to the grid, and the homeowner is given a credit for his electricity production.

Blue Link Solar Network of Arundel is targeting precisely these consumers with the simple “plug and play” system installed at the State House. Three hinged panels sit atop an electric meter and the whole unit plugs directly into a transformer with a single line.

“Our whole goal is to get solar power into the mainstream,” said Blue Link managing partner Charlie Langston.

Maine has more solar energy potential than most people realize, he said. The state has an average of four hours of peak sunlight per day, not that much less than the six hours produced in the heart of the Arizona desert, he said.

Since the company was created eight months ago, six of the $4,650 systems already have been installed in Maine, with about the same number scattered elsewhere in the country. Langston estimated that a typical household would save about $80 annually in energy costs. And if the proposed incentive program is approved, Maine customers would pay only about $3,200 for the system.

But most of Blue Link’s customers aren’t getting into solar energy for economic reasons, he said, citing clients concerns about the war in Iraq and the environmental consequences of fossil fuels.

Mainers are seeking out renewable, domestic energy sources. Maine Interfaith Power & Light is selling wind, biomass and hydroelectric power to more than 3,000 customers. Vehicles owned by the state and the city of Bangor are converting to plant-based biodiesel. And the state’s first wind farm, atop Mars Hill Mountain in Aroostook County, should be under construction in a matter of weeks.

“Every time we go to fill up the gas tank, we see that we need to do things a little differently in this state,” said the solar incentive bill’s co-sponsor Sen. Jon Courtney, R-Springvale.