A house of independent means - solar- and wind-powered home in Nicasio, California

Sunset, March, 1996 by Peter O. Whiteley

Sun, wind, and propane are all that power a house in Northern California, with no compromise on amenities

No power, gas, or water lines run to Anoosh and Kija Mizany's hillside home in Nicasio, California. No monthly electric bills arrive in the mail. With the exception of a telephone line, the Marin County house stands - in the lingo of the solar power community - "off the grid" of public utility power lines. The Mizanys use the sun and the wind to meet most of the energy needs in their 4,500-square-foot house.

Unlike many of the experimental solar homes built in the 1970s and 1980s, the Mizanys' house gives little outward hint of its energy independence. With a composition shingle roof, plywood siding, landscaped grounds, and a swimming pool, the house looks like a traditional ranch-style home. Inside, the appearance and amenities show no compromise on comfort: high ceilings, indirect lighting, ceiling-mounted down lights, a full kitchen with a pair of refrigerators, a central vacuum system, a whirlpool-style bathtub, televisions, stereos, tile and wooden surfaces over radiant-heated floor systems, and a three-car garage with automatic openers.

However, you can't help but notice the array of solar panels on the south-facing roofs of the garage and main house. Panels on the house are solar thermal panels for the hydronic system that heats water for the pool, domestic use, and the radiant floor, and the ones on the garage are state-of-the-art photovoltaic (PV) panels, which convert sunlight to direct-current electricity. The 50 PV panels combine to make a self-contained mini-power station that can produce 15 kilowatt-hours of power a day in summer months and about 8 in winter months.

Elsewhere on the property are smaller arrays of PV panels that power the pool filtration pump and a pump that brings well water to two 1,700-gallon storage tanks buried uphill from the house (the elevation change creates the water pressure). In addition, two wind-driven generators rising from the hillside site contribute 3 to 5 kilowatt-hours of power during windy days - enough to run the Mizanys' two energy-efficient refrigerators for 48 hours.

None of this power comes cheap. Anoosh Mizany estimates the cost of panels, additional equipment, control panels, storage batteries, and a backup generator to be about $45,000. However, the cost of bringing the local utility service to the remote site would have been twice as high. He figures that the savings in operating costs will be even greater over the long run, since the only thing the Mizanys will pay for is propane. The couple's decision to tap the power of sun and wind mirrors the reasoning of other homeowners who've considered going off the grid: a photovoltaic system makes economic sense for remote locations, but it rarely does for houses where electric power is more readily available.

HOW THIS PHOTOVOLTAIC SYSTEM WORKS

In simple terms, a PV panel contains silicon wafers (semi-conductors) connected in a grid. When sunlight strikes them, electrons are freed to move through the grid in a circuit that can run a motor or charge a battery. Scaling the system up to meet the energy needs of an entire house requires a number of panels and batteries big enough to store several days' worth of electricity. At the Mizany residence, the electric energy is stored in two huge batteries, each weighing more than 1,500 pounds.

"We sized the house system to the worst - meaning shortest - day of the year, which is in mid-December," explains Mizany. "We aimed to provide 80 percent of our energy needs for that day, with the generator adding the remaining 20 percent." With help from experts at Solar Depot in San Rafael, California, he determined the number of PV panels needed, as well as the size of storage batteries and all related equipment, and integrated the thermal, solar, and wind systems. The process included an analysis of expected energy usage and a willingness to substitute appliances that demand less energy. For instance, he selected the company's special energy-efficient refrigerators and state-of-the-art fluorescent fixtures with warm-tone lamps for all lighting. He also chose an oven, a cooktop, and a backup boiler for the radiant system that all use liquid propane instead of electricity. Three high-efficiency woodstoves help heat the house in winter.

The house is now 3 years old, and the average yearly cost for the propane (an expensive fuel) runs about $800. Once every two to three months, Mizany checks the batteries' electrolyte level; after 200 hours of generator running time, he must change the oil and filter, and periodically he must tune up the backup generator.

The well-conceived system has proved itself. As Mizany proudly says, "In one of last year's storms, the local power went out for several days, and we were the only house on the hill with lights on."