How it works
Peak sun hours represent the equivalent number of hours at full 1,000 W/m² irradiance per day — it converts variable sunshine into a single daily multiplier. Multiplying by system size gives theoretical output, then the efficiency factor deducts real-world losses (inverter conversion, wiring, panel temperature, soiling and shading).
Worked example
6.6 kW × 4.5 h × 0.80 = 23.76 kWh/day. × 365 = 8,672 kWh/year. At 30 ¢/kWh that's about $2,600/year in avoided electricity cost.
Assumptions & limitations
Uses a flat annual average for peak sun hours — output is higher in summer and lower in winter. Real production depends on panel orientation, tilt, shading, and inverter clipping if the array is oversized relative to the inverter.