Energy Estimation Formula:
Annual PV System Performance= (sun hours) x (de-rating factor) x (system totals Watts-STC) x 365 days x Acorr
Where, Accor= azimuth correction from due south–therefore, Acorr=1.0 if azimuth of PV array is due south (180° or 0°).
PVWATTS calculates electrical energy produced by a grid-connected photovoltaic (PV) system. Researchers at the National Renewable Energy Laboratory developed PVWATTS to permit non-experts to quickly obtain performance estimates for grid-connected PV systems within the United States. To access this calculator, go to PVWATTS Version 2. Learn more about the PVWATTS calculator