The PV Process
If providing solar is in your future as a builder, the process begins all the way back on the boards, with a land plan and set of models that ensure homes in the community have adequate exposure and orientation to the sun.
That discipline is easiest to follow when there’s a big empty parcel, but hardly impossible with an infill or scattered-lot opportunity.
For Encore, a 45-unit, single-family, two-parcel infill project nearing sold-out status in Vacaville, Calif., Meritage Homes easily accommodated PV. “We were able to orient the streets and place the houses in accordance with the approved plat to maximize the exposure to the sun,” says Kramer.
Meritage also leveraged a handful of existing house plans in its portfolio for Encore, rather than designing a new or specific set of models to suit the 2.3-kWh roof-mounted PV systems offered as standard on all 45 homes. Simply, the builder thoughtfully placed the 2,080- to 3,714-square-foot units within the land plan to achieve the best orientation and exposure for a PV system—while also meeting objectives for a varied streetscape and other marketing and sales considerations.
To achieve adequate exposure and output, a typical residential system usually requires about 100 square feet of clear surface area per kilowatt of PV capacity. The system should be able to satisfy about one-half to three-quarters of the home’s electricity demand. For most single-family homes, that’s between 1 and 3 kWh.
The array should face due south at an angle that matches the location’s latitude to enable at least six hours of daylight to hit the panels year-round. That being said, some solar experts say a 15- to 20-degree variation east or west from due south won’t significantly degrade the system’s effectiveness. A slightly southwesterly exposure, in fact, might perform better during peak-use hours, when solar’s value really shines.
Regardless of where you build, in heating or cooling climates, the key is to make sure the panels aren’t shaded and intruded upon by vent pipes and other penetrations through the roof structure, the latter of which might require some adjustments on the mechanical plan and upfront consultation.
“Builders have to start thinking of the roof as prime real estate,” says JoEllyn Newcomb, general manager of Independent Power Systems in Boulder, Colo., a residential PV designer and installer. “Think of the roof as a potential power plant.”