You enter your monthly electric bill, the rate you pay per kWh, average daily sun hours for your area, and your preferred panel wattage. The tool divides your bill by the rate to estimate monthly usage, scales to annual kWh, then sizes a system to match that output given your sun hours. Install cost uses a $3/W national average. It does not factor in tax credits, net metering, or panel degradation.
The NREL PVWatts tool or the Global Solar Atlas provides peak sun hours by location. In the U.S., values typically range from 3.5 hours in the Pacific Northwest to 6+ hours in the Southwest.
No. The federal Investment Tax Credit (ITC) can reduce your net cost by 30% through 2032. Apply it to the install cost shown here for a more accurate out-of-pocket figure.
$3/W is a commonly cited national average for fully installed residential systems including equipment, labor, and permitting. Actual prices vary widely by state, installer, and roof complexity — quotes typically range from $2.50 to $4.00/W.
Panels degrade roughly 0.5% per year, so output in year 25 is typically about 87–90% of year-one production. This calculator assumes constant output for simplicity.
This calculator estimates grid-tied solar without batteries. Adding a battery (typically $10,000–$15,000) extends payback but provides backup power and may help with time-of-use rate savings.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.