Larry Bohs

His passive solar house is a model of efficiency

ORANGE COUNTY -- "It's a great day for solar power," Larry Bohs declares, surveying the brilliant azure sky.

The sunlight is clear and strong, not obscured by clouds or haze.

To this Duke University biomedical engineering professor, the nation's energy future depends on solar photovoltaic panels mounted on a wooden shed on his seven-acre property, about six miles from Duke University.

The electricity flows in two directions here. While Bohs' house is using electricity from the Piedmont Membership Electric Cooperative, the 2-kilowatt panels on his shed are generating power that Bohs sells back to the co-op. "We generate twice as much [power] as we use," he said.

With a solar subsidy from N.C. Green Power, a nonprofit organization in Raleigh, Bohs nets a small profit on his $15,000 solar electric generating system. In June, his electricity bill was $22, offset by a $35 payment from N.C. Green Power.

The family expects to recoup about 80 percent of their $15,000 investment over five years through federal and state incentives.

Still, you can do the math: Solar power is no get-rich-quick scheme. And it requires efficiency to be financially viable.

Accommodating a family of four, the Bohs' super-efficient home uses about 90 kilowatt hours per month, consuming the amount of electricity in a month that most households use in two days. Progress Energy's typical household in North Carolina uses about 1,200 kilowatt hours per month.

"It's not hard, anybody can do it," Bohs says. "The way we live isn't that different from the way anyone else lives."

Bohs cultivates Frog Pond Farm, a pick-your-own berry farm with blueberries and blackberries. He also grows heirloom apples, cherries, figs, muscadine grapes, mulberries, peaches, pears, plums, persimmons, pawpaws and raspberries, mostly planted in the clearing under utility transmission lines run by the electric cooperative and Duke Energy.

The sun is at work everywhere.

A 10-watt solar panel powers an electrified fence to zap the deer that would feast on Bohs' fruit orchard.

A 75-watt solar panel runs the electric pump that draws water from a nearby pond to irrigate the orchard.

The water is pumped to two 500-gallon tanks and released by gravity, flowing downhill to the berry bushes and fruit trees. "This is my favorite alternative energy apparatus," he said. "It tickles me every time I turn this valve."

When he's not mulching, weeding or pruning, he rides his bicycle to campus for his regular day job.

The family home is less than two years old, with siding milled from pine trees growing on the property. The posts, beams, cabinets and trim are all pine and cedar. Bohs, his wife, Libby Searles-Bohs, and the couple's two children, who are 7 and 11, live in the 1,500-square foot house.

The home's passive solar design is "the key to energy savings," Bohs said. In the winter, sunlight penetrates 12 feet into the living area and warms up a concrete slab on the floor. The family also uses a wood-burning stove for heating.

About a third of the home's energy is used by the refrigerator -- an energy-efficient model, of course. They use propane for cooking and the water heater. There's no television or clothes dryer.

Six ceiling fans cool the house in the summer.

"You can reduce your need for air conditioning by 5 [degrees] to 10 degrees," Bohs said. He uses a window air conditioner unit, but mainly as a dehumidifier.

"We enjoy figuring out how low we can get on our power usage," Bohs said. "What we're doing is not going to be unusual in 10 years."