Builders who expect to install a solar system, whether during new construction or at a future date, should design and orient the home to provide at least one roof section with an unshaded, south-facing roof slope suitable for a solar array.
According to Coley Fudge of Alteris Renewables, a Vermont-based company that installs solar equipment from a number of manufacturers, roof pitch is another important factor, but it doesn’t limit a builder’s or homeowner’s options. In the Northeast, he explains, “a 45-degree roof angle is ideal, but in summer it doesn’t really matter—you’re going to get 100% [of solar radiation] from a 30- to 40-degree slope. In summer, the ideal angle is only 32 degrees.” Alternatively, roof mounts may be used to improve the collector position on less-than-optimum roof pitches, and solar arrays can be installed on ground-mounted racks when necessary.
Builders also should consider roughing-in the pipes and wiring for solar systems to be installed later, or at least installing a chase for these lines. For the plumbing, Alteris recommends using ¾-inch-diameter copper tubing, and recommends against using plastic or PEX-type tubing.
Although the sun rises every day, it is not reliable as the sole source of hot water in most geographic locations. Building and plumbing codes recognize this and dictate that a fuel-fired heater be provided to support 100% of a home’s hot water needs, regardless of whether a solar-heating system will be added. As a result, solar thermal systems are sized to supplement, not replace, a home’s own water heater. Solar manufacturers are just beginning to adapt their products to satisfy the code demands. One recently introduced system, Caleffi’s Solarie Solar Heat Pump, eliminates the need for a separate water heater by including a backup gas or electric heating element in its storage tank to provide hot water when the sun cannot.
Buyers should beware that, in order to qualify for federal and most state incentives, the key components of all solar systems—the solar collectors—must meet industry certification standards. The most widely accepted certification is bestowed by the SRCC, which tests and approves solar equipment and systems based on ASHRAE standards. Another third-party organization, IAPMO R&T, certifies equipment according to ANSI standards.
Installing solar water heaters qualifies homes for points under most green certification programs. LEED for Homes offers two points for backup systems accommodating more than 40% of the annual load and three points for systems that account for 60% or more. The ANSI National Green Building Standard awards points (from eight to 20) toward certification for solar water heaters on a scale tied to their SRCC Solar Energy Factor rating.
Michael Morris is a freelance writer in Ossining, N.Y.