HousingZone.com

September 1, 2001
HousingZone

	Built by Solar Strategies Manufactured by Design Homes

SBIC was one of fourteen organizations who helped make this demonstration project possible.

The Solar Patriot has two different photovoltaic systems – building-integrated photovoltaic (BIPV) shingles and low profile solar panels – that provide sufficient power for the home to operate completely independent of the utility grid… even on cloudy days and cold winter nights. In addition, a solar hot water heating system accommodates all of this 3,000 s.f. four-bedroom, two-story home’s domestic hot water (DHW) needs. Together, the photovoltaic systems willgenerate 6 kilowatts of energy; enough to handle the demand for all electricity usage in the home. Electricity is stored in eight 75 amp batteries, and an inverter converts the DC electricity produced by the panels and thin-film BIPV shingles to 120 volt AC current; the same electricity that flows through the wiring and outlets in your home.

Energy from the sun is free, clean, and above all, renewable. This means that as long as the sun continues to rise in the east each day, it’s power can be converted to electricity using technologies and systems such as those you see deployed here. But energy efficiency and sustainable, ‘green’ building practices aren’t just about where the power comes from. It also has a lot to do with how we can get the most out of whatever power we choose – solar, wind, geothermal, fuel cells, or any of the other more traditional sources that are proving to be increasingly finite, costly, (and therefore nonrenewable) in nature.

According to BP Solar, manufacturer of the solar arrays mounted in the center section of the Solar Patriot’s roof, photovoltaic (PV) or solar cells operate on the principle that electricity will flow between two different semiconductors when they are placed in contact with one another and exposed to light (the semiconductors are made of silicon that is refined to 99.9999% purity). By linking a number of these cells together, a useful flow of electricity can be gathered. Such a collection of PV cells constitutes a PV module.

To make the most of the power it receives from the sun, the Solar Patriot uses R-21 insulation in walls and R-38 in the ceiling. High performance, double-pane windows with low-e coatings round out a highly efficient building envelope – another name for the home’s outer shell. Passive solar strategies – those which function without any moving parts – include placement of the majority of windows on the home’s south side, with appropriate shading, to take optimum advantage of seasonal variations in the sun’s path.

An efficient envelope is important, because it’s the part of the home that keeps the outside out and the inside in. How well the building envelope does its job determines everything from the size (and cost) of the heating, cooling, and ventilation system; to the amount of moisture that penetrates the house (too much can result in problems like mold growth and other indoor environmental irritants), the amount of UV light that enters the home (causing furniture, carpets, and finishes to prematurely fade), and the big-ticket item that’s on everyone’s mind these days: the monthly heating and cooling bills.

Even though it costs a bit more to outfit a home with higher levels of insulation, better quality low-e windows, and other green building products and materials, these strategies usually let you downsize your HVAC system. The reduced cost of the HVAC system can offset much of the increase in material costs required for a better envelope, so it ends up being close to a wash. If it does cost a bit more (depending on you local climate and builder capabilities), the increase usually pays for itself in the first few years’ worth of reduced utility bills. As fuel prices continue to rise, the simple payback period – the time it takes to recoup the difference in construction costs between conventional and high performance materials & equipment – gets shorter. Not that we’re rooting for higher energy costs (we’re not), but if nothing else, they help underscore the inherent value of sustainable design.

Energy efficient lighting and appliances round out the overall ‘whole building design’ approach by helping reduce the home’s overall energy use by as much as 40%. By itself, compact fluorescent lighting throughout the home will yield a 20% savings in the average homeowner’s energy use. Together, the high performance building envelope, energy efficient lighting and appliances will reduce the home’s overall construction cost by reducing the size of the solar energy system by over 60%.

A unique feature of this zero-energy home is the fact that its owner will be able to sell any unused, excess solar energy back to the utility for use in the clean power market. Virginia, along with 31 other states, has passed legislation enabling net metering for individual homeowners who produce their own power. Here are some of the Solar Patriot’s other renewable energy and sustainable design features: