SOLAR TODAY Blog

By Chris Stimpson
Solar Nation Executive Campaigner

The first decision to be taken on the weekend of the National Solar Tour consists, in fact, of several decisions. How many sites to visit? How far to drill down into the owners' decision-making process and experiences? Whether to poll other visitors for their plans and concerns?

In the end, I chose three sites within twenty miles of my own (non-solar) apartment complex in west-central Maryland, and was well rewarded by the experience. The first was the 2700-square foot home of Donald and Susanne Wiggins of Germantown. Their 1.5-kW rooftop PV array is actually a hybrid system, in which bladders containing an ethanol glycol mixture -- a heat transfer medium -- are located beneath the amorphous silicon panels. As the panels heat up, the mixture removes excess heat from them and delivers it to a heat exchanger in the basement, which pre-heats the water in the hot water tank. The system was installed some seven years ago by Capital Sun Group of Cabin John, MD, and according to the Wigginses has been working well for them.

Susanne Wiggins told me they had benefited from federal and state tax credits for Solar when they installed their system, but had held off from adding geothermal heating. Montgomery County offered a subsidy for geothermal, but it was in the form of a property tax abatement, and since the subsidy rolled over from year to year, the County would have to discharge its backlog from previous years before allowing new applicants to enjoy the relief.

"We'll fight that one another day," remarked Susanne.

Also in Germantown I found the buildings of the Dayspring Earth Ministry, a retreat facility linking faith and ecology. This was an example of several renewable energy/energy efficiency technologies working symbiotically. I found ground-mounted and rooftop PV panels as well as solar hot water panels on the facility's buildings. The main building contained:

• 8-inch-thick walls super-insulated with blown cellulose from recycled newspapers and with exterior foam sheathing;
• a high-efficiency dehumidifier capable of removing 65 pints per day;
• a masonry stove heater with bake oven and a highest-efficiency wood-burning stove;
• stained concrete floors that absorb solar heat and release it slowly;
• overhanging, vine-bearing eaves on the south side, reducing unwanted solar heating in summer months;
• insulating blinds;
• kitchen/dining room floors of sustainably harvested bamboo;
• a insulating 'green' roof.

With all the passive solar and energy-efficiency features incorporated in the design, the 1.5-kW rooftop array has been able to supply 100% of the building's electrical needs for their first two years of operation.

My final stop of the day was at the Red Wiggler Community Farm, a non-profit organic farm providing job training and employment for adults with developmental disabilities, as well as youth service jobs and educational programs on environmental stewardship. It's here that the University of Maryland's 2005 Solar Decathlon entry, an 800-square-foot grid-tied house, has been relocated. The house features fifty-one 175-watt PV panels on a curved roof, and evacuated-tube solar water heating on the south-facing wall; the latter array powers a hot water radiant floor as well as the domestic hot water system, using propylene glycol as a transfer fluid.

The building serves as a home and office for Woody Woodroof and Debra Graugnard, who run the community farm. In the basement, Woody showed me the compact electrical management system, housing the electrical disconnect switches, the inverter and battery back-up rack. Back upstairs, Debra pointed out the triple-pane windows, cedar siding, recycled glass tile, and flooring of recycled rubber and bamboo. She also managed (quite easily) to relieve me of a dollar for some of the garlic organically grown on site.

So in all my visits to solar-powered homes, I found what I had hoped to find: buildings that borrowed from a wide range of active solar, passive solar, and energy efficiency techniques to create truly green (and usually 'net-zero') building envelopes. Most of these techniques cost little more than their mainstream alternatives, and ought themselves to be becoming 'mainstream' in years to come.