How Much Power Can Your Home Solar System Generate?
Solar output varies dramatically by US region. The Southwest (6.5 peak sun hours/day) produces more than twice the output of the Pacific Northwest (3.0 peak sun hours/day) from the same panel system. This calculator uses the formula: Monthly kWh = panel capacity (kW) × daily peak sun hours × 30 × 0.78, where 0.78 is a standard performance ratio accounting for temperature derating, inverter losses, and wiring inefficiencies. A 5 kW system in the Southwest generates roughly 760 kWh/month; the same system in the Pacific Northwest generates about 350 kWh/month.
Actual output can vary ±20% based on panel tilt angle, roof orientation, shading from trees or neighboring structures, and seasonal weather patterns. This tool provides a regional average estimate — a certified solar installer can give you a site-specific projection using satellite irradiance data. Use the annual savings figure alongside system cost to estimate your payback period.
Frequently Asked Questions
The US average is around $0.13–$0.17/kWh, but it varies widely by state — Hawaii averages over $0.35/kWh while Louisiana is under $0.10/kWh. Check your utility bill for your exact rate.
Divide your total system cost (after tax credits) by the annual savings figure. For example, if a $15,000 system (after the 30% federal ITC) costs $10,500 and saves $1,500/year, payback is about 7 years.