Solar Savings Calculator
What a Solar System's Nameplate Rating Doesn't Tell You
A solar system's kW rating describes its capacity, not what it actually produces — real-world output depends on how many peak sun hours a location gets and how efficiently the system converts that sunlight to usable electricity after inverter losses, shading, temperature effects, and panel soiling. This calculator translates system size and location-specific sun exposure into an actual annual dollar savings figure, not just a capacity spec.
The Formula
Annual Savings = Annual Output × Electricity Rate
Performance ratio (default 80%) captures the gap between theoretical maximum output and real-world output after system losses — a widely used simplification in residential solar estimates, though actual performance ratios vary by installation quality and climate.
Where This Estimate Matters
- Evaluating a solar quote — comparing an installer's projected savings against an independent calculation using the same inputs is a useful sanity check before signing a contract.
- Sizing decisions — running the numbers at a few different system sizes shows how much savings scale (or don't) as panel count increases, which matters for budgeting the upfront cost.
- Payback period estimates — annual savings is the number that gets divided into system cost to estimate how many years until a solar investment pays for itself.
Worked Example
| Input | Value |
|---|---|
| System size | 6 kW |
| Peak sun hours/day | 5 |
| Electricity rate | $0.15/kWh |
| Performance ratio | 80% |
| Annual output | 8,760 kWh/year |
| Annual savings | $1,314.00/year |
Figures computed directly from the calculator's own formula: 6 × 5 × 365 × 0.80 = 8,760 kWh, × $0.15 = $1,314.00. Actual savings depend on your utility's rate structure, including net metering policy and time-of-use rates, which this simplified model does not account for.
How to Use This Calculator
- Enter the Solar System Size in kW.
- Enter the Peak Sun Hours per Day for your location.
- Enter your Electricity Rate in $/kWh.
- Optionally adjust the Performance Ratio percentage (defaults to 80%).
- Select Calculate to get annual output and savings.
Related Calculations
Compare that output against your actual household draw with the Energy Consumption Calculator, or see how much CO2 that displaced grid electricity represents with the Carbon Footprint Calculator.