Residential Grid-Direct Photovoltaic System: Koller Residence
Inside this Article
To speed the deployment of residential PV systems and increase operational and marketing...
Bonnie Johnson and Paul Torrence represent ideal candidates for a residential grid-tied system. The...
A 7.2 kW system that provides 3 days of autonomy for critical loads, which include home business...
GreenLogic Energy was selected from more than 200 SunPower dealers in North America to receive the 2009 SunPower Residential Dealer of the Year award. The custom-attachment approach used on the Koller project is one example of the company’s leadership in the residential market and its quality installation standards.
To meet the customer’s aesthetic needs, the garage roof was selected as the ideal location for the array. The roof is supported by 3.5-by-11-inch wood beams sheathed with 2-by-4 tongue-and-groove cedar with 2 inches of rigid foam insulation between the sheathing and the 30-year architectural shingle roofing. This construction made the attachment approach extremely challenging. To meet the stringent local design criteria, GreenLogic consulted with a New York–certified engineer and the technical support staff at Unirac to develop a customized attachment technique.
To minimize potential uplift forces, the array is installed in Roof Zone 1. Each row of modules has three SolarMount HeavyDuty Rails that are secured to the structural beams with hanger bolts and Unirac serrated L-feet. Each hanger bolt has 6 inches of thread embedded in the corresponding beam. The use of hanger bolts required an alternative flashing approach that utilizes a silicone gasket and washer combination at each attachment point.
“After we calculated the required hanger bolt length, we completed an exhaustive search and determined that the bolts needed to be custom fabricated. The design and procurement phase of this project was challenging, due to the atypical roofing material buildup. Once that phase was completed, the installation went well and without a hitch.”
— Ashlee Reiniger, GreenLogic Energy
DESIGNER: Ashlee Reiniger, senior project manager, GreenLogic Energy, greenlogic.com
LEAD INSTALLER: Matt Krisko, GreenLogic Energy
DATE COMMISSIONED: June 24, 2009
INSTALLATION TIME FRAME: 5 days
LOCATION: Shelter Island, NY, 41°N
SOLAR RESOURCE: 4.3 kWh/m2/day
RECORD LOW/AVERAGE HIGH TEMPERATURE: -7°F/88°F
ARRAY CAPACITY: 5.52 kW
AVERAGE ANNUAL AC PRODUCTION: 5,982 kWh
MODULES: 24 SunPower SPR-230- WHT, 230 W STC, +5%/-5%, 5.61 Imp, 41.0 Vmp, 5.99 Isc, 48.7 Voc
INVERTER: SunPower 6000m, 6 kW, 600 Vdc maximum input, 250–480 MPPT range
ARRAY: Eight modules per source circuit (1,840 W, 5.61 Imp, 328 Vmp, 5.99 Isc, 389.6 Voc) with three circuits total (5,520 W, 16.83 Imp, 328 Vmp, 17.97 Isc, 389.6 Voc)
ARRAY INSTALLATION: Unirac SolarMount HD rail system, 129° azimuth, 15° tilt
ARRAY COMBINER: Inverter integrated with dc disconnect, 20 A series fuses