Annual energy estimates for multi-array residential systems, modeled with the National Laboratory of the Rockies PVWatts® v8 engine.
Enter a five-digit US ZIP code for the most reliable result. A city name also works anywhere in the world, though matches outside major metro areas can be imprecise or fail entirely.
Optional. Fill in a panel wattage and each array will accept a panel count instead of a kW size, and size itself from that. Leave it blank to enter kW directly.
Azimuth is the compass direction the modules face: 180° is due south, 90° east, 270° west. Tilt is the roof pitch in degrees from horizontal — a 6:12 pitch is about 27°.
Default losses were not changed. Every array is modeled at the PVWatts default system loss of 14.08%, which bundles soiling, wiring, connections, mismatch, light-induced degradation, nameplate tolerance, availability, and a nominal shading allowance.
Site-specific shading is not accounted for. Trees, chimneys, dormers, parapets, adjacent structures, and row-to-row self-shading are not modeled. A site with real obstructions will produce less — sometimes substantially less — than what is shown here.
All arrays are modeled as fixed roof-mounted with standard modules, at a 1.2 DC-to-AC ratio and 96% inverter efficiency. Weather data is a typical meteorological year, so a single real year will fall above or below the estimate. These figures are a modeling estimate for comparison and screening. They are not a performance guarantee.