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Estimate solar panel savings, payback period, and 25-year return on investment.
A solar panel savings calculator estimates annual electricity savings, payback period, and 25-year return from a residential solar installation based on system size and local conditions.
| Region | Hours/Day |
|---|---|
| Southwest (AZ, NV, NM) | 6.0 – 7.5 |
| Southeast (FL, GA, SC) | 4.5 – 5.5 |
| Midwest (IL, OH, IN) | 3.5 – 4.5 |
| Northeast (NY, MA, CT) | 3.5 – 4.5 |
| Pacific NW (WA, OR) | 3.0 – 4.0 |
| Mountain (CO, UT, MT) | 5.0 – 6.0 |
Formula
Annual Savings = System Size × Sun Hours × 365 × Efficiency × Electricity RateSystem Size = capacity in kilowatts (kW)
Sun Hours = average daily peak sun hours
Efficiency = system efficiency factor (typically 75–85%)
Electricity Rate = cost per kWh from utility
Worked Example
6 kW system, 5 sun hours, $0.15/kWh, 80% efficiency
Did you know? The cost of solar panels has dropped by 99% since 1976, from $106 per watt to under $0.30 per watt in 2024 (source: National Renewable Energy Laboratory).
Sources
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