The Gribbens have 27 panels on the back (south-facing) roof of their Holger Court house, a 5.8-kilowatt array that covers about three-quarters of the roof.

The array was completed in May of last year and provides about 70 percent of the power they need, Chip Gribben said. They still rely on Baltimore Gas and Electric for the balance, he said, but going solar has slashed their electric bills from more than $100 a month to $10 or $20.

The new solar array also charges the Gribbens' electric car — and their electric ride-on mower.

Like the Gribbens, Charles and Judith Goedeke had solar panels installed on their North Laurel house in May of last year: 14 panels to supplement the two they'd installed the previous year to heat their water. Their energy use from BGE now is less than 25 percent of what it was.

Also like the Gribbens, they were a green family long before that. Very green, in fact.

The Goedekes, who live on Patuxent Ridge Way, have landscaped their home to manage runoff and compost their vegetable scraps to use in their flower gardens. They drive a Toyota Prius, use ceiling fans to keep their house cool in all but the hottest weather, and have not used a clothes dryer in five years, instead using drying racks.

They use high-efficiency light bulbs, environmentally friendly cleaning products, shop for used items whenever they can and have installed floors made of stranded bamboo (easily renewable grass) throughout their house.

"We are far from perfect," said Judith, 60. "But we do seriously evaluate our choices and very heavily favor living simply and living well."

Charles, 63, said waiting to install solar was a matter of economics.

"As much as I would've loved to (install the panels earlier), it would have been twice as expensive and not as productive," he said. It would've taken 20 years to break even if they'd installed the panels just a few years ago, he said, but now, they expect to do so in six or eight years.

"So economically it's a good idea, and it's good for the planet," Goedeke said. "It's the old saying: 'Do good while doing well.' "

Organizers hope the solar tour convinces other homeowners to feel the same way.

"We've found the solar tours are very valuable, because people can actually see solar panels in use in a home, see how they work," said John Essig, chairman of the board of the Mid-Atlantic Solar Energy Society, which organized the local event. "And they can get information from real people. … That really helps people learn how solar works, and what it can do for them."

This year's solar home tour will be held Saturday and Sunday, Oct. 5-6.  Guidebooks listing the homes on the tour, including a map and addresses, are available at area MOM (Mom's Organic Market) stores for $5 or can be downloaded for free at solartour.org