CostSolar Savings & Payback Calculator
Estimate annual electricity savings and simple payback period for a solar system.
Enter values and press Calculate.
How this calculator works
System size is multiplied by average sun hours and a performance factor to estimate annual generation. Generation is multiplied by electricity price to estimate avoided electricity cost.
How to use the result
A 5 kW system with 4 peak sun hours per day and an 80% performance factor models 5,840 kWh per year. At $0.18 per kWh, valuing every kWh at the retail rate gives about $1,051 per year. If half the generation is exported at $0.06 per kWh and the other half offsets retail purchases, the same generation is worth about $701 per year. Check how your utility credits exports before using the displayed simple payback.
Frequently asked questions
What is the performance factor?
It is a simplified allowance for inverter losses, temperature, wiring, shading and other system losses.
Is payback guaranteed?
No. This is a simple estimate and does not model financing, degradation, maintenance, export tariffs or future electricity prices.
What sun-hours value should I use?
Use a reliable local solar-resource estimate for your location.