PHOENIX — No monthly electric bills in this desert city where, in the summer, temperatures routinely soar to 112 degrees, and the owner of a conventional home steels himself for air conditioning expenses of $300-$350 a month?
That's the promise being held out to buyers in a quiet, park-bordered, 24-home development now under construction on Phoenix's northwest side. Not only are they being assured that, once in place, those homes will trigger no electric bills, but that, as owners, they may receive checks from the utility.
For long-time Phoenix home builder John F. Long, Solar 1 is the culmination of a lifetime fascination with energy efficiency. It's certainly the first time, anywhere in the world, that an otherwise conventional housing development has been designed as a mini-utility, not merely 100% solar efficient--creating its own electricity directly from the sun-- but capable of producing energy beyond its own needs.
At the heart of Long's Solar 1 project is the energy center for the development: a rectangular 74-by-131-foot enclosure, bounded by an eight-foot wall that screens it from both the houses and adjacent Osborn Road traffic. The center consists of 3,600 photovoltaic panels (132,000 cells, in all) measuring four feet long, 16 inches across, and slanted on seven-foot racks to capture the rays of the burning Phoenix sun.
"We're gridded into the electric utility, the Salt River Project," Long explains, "which means that during the day we'll be selling our excess energy to the SRP at the peak-hour rate, which is 5.7cents per kilowatt hour and then, at night and on inclement days, we'll draw energy \o7 back \f7 from them at, normally, the off-hour rate of 3 1/2 cents per kilowatt hour. Ideally, the system has been designed to produce a zero balance over the course of the year."
Still and all, Long emphasizes, the photovoltaic system designed for him by Chatsworth-based Arco Solar, Inc. (a wholly owned subsidiary of Atlantic-Richfield), would fall far short of being cost-effective without the utilization of passive components in the homes, themselves--the key element being a building technique more than 800 years old.
"The Hohokam Indians, who lived around here before disappearing about AD 1100, " Long explains, "didn't try to fight the environment, but learned to live with it, and the heart of it was rammed earth construction--extremely thick walls with the insulation on the outside instead of the inside so that they acted as thermal storage."
Thus, the six model homes in Solar 1 come equipped with 21-inch rammed earth walls--a wetted-down mixture of sand and dirt held together with cement (about 7%). The mud mix is poured into forms, packed down with pneumatic hammers and the walls are then allowed to dry.
"It's like living in a basement above ground," he adds, "but it was important to me that the houses, otherwise, be of conventional design. Most houses that go heavily into passive solar design end up so funny looking that they turn people off."
And there is nothing "funny looking" about the attractive Solar 1 homes, which range from two to four bedrooms, from 1,600 to 2,200 square feet and are priced from $110,000 to $125,000. The abnormal thickness of the exterior walls is virtually undetectable.
But, in addition to the rammed earth walls (in terms of insulation rated R-27), other passive features include double-paneled windows, a combination evaporative cooler/refrigeration air-conditioning system, low-use appliances, such as water-saver toilets, solar water heaters and R-50 ceiling insulation. A measure of heat resistance, the higher the R rating the more effective the insulation.
"There are also shade screens on all east/west windows," Long adds, "and we've put infra-red aluminum barriers in the attic right under the sheathing which deflect the long rays of the sun, the ones that penetrate conventional insulation."
But it is still Solar 1's role as a mini-utility releasing its homeowners from their dependence on the local electric utility that makes it, in the literal sense of the word, unique.
"There have been some Third World villages that have been equipped with photovoltaic generators," according to Jerry Reznick, Arco Solar's manager of marketing communications, "but these are situations where they had absolutely nothing before, and their governments picked up the cost to bring them some sort of basic power--enough for electric lights, water pumping and communications. And there have been some commercial applications of course, but, to our knowledge, no one has tried what Long is doing--making an entire housing development energy-self-reliant this way."