Solar Yield Audit
Forecast the energy production of your PV array. Real-world analysis accounting for system losses and geographical sun density.
System Data
75% - 80% is typical for grid-tied systems.
The Output Formula
Solar energy yield depends on your array's rated capacity and how many productive sun hours your location receives.
Daily Energy Yield
kWh/day = kWp × Sun Hours × Eff kWp is the peak power of your array in kilowatts. Efficiency (typically 0.75–0.85) accounts for inverter, cable, and temperature losses.
Annual Yield
Annual kWh = Daily kWh × 365 Use annual yield to calculate CO₂ offset, savings vs. grid electricity cost, and payback period for your solar investment.
How to Estimate Solar Panel Output
Knowing how much energy your solar system will actually produce is the foundation of any solar investment decision. The theoretical output of your panels (kWp) is always higher than real-world production — temperature, shading, inverter losses, and dust all reduce actual yield. This calculator applies a realistic efficiency factor to give you an honest production estimate.
Performance Ratio: The Key Metric
Performance Ratio (PR) is the ratio of actual energy output to theoretically possible output — the single best measure of a solar system's real-world efficiency. A well-installed system typically achieves a PR of 0.75–0.85. Losses come from inverter conversion (3–5%), cable resistance (1–2%), soiling (2–5%), temperature derating (5–10%), and shading (variable).
Factors That Affect Solar Output
- Peak Sun Hours: The most location-dependent variable. Phoenix, AZ sees ~6.5 peak sun hours; Seattle, WA averages ~3.5. Use your local solar irradiance data for accuracy.
- Panel Temperature: Solar panels lose approximately 0.4% of output per degree Celsius above 25°C (STC). A panel at 65°C on a hot day produces ~16% less than its rating.
- Shading: Even partial shade on one panel can significantly reduce the output of the entire string in traditional string inverter systems. Microinverters or DC optimizers mitigate this.
- Panel Orientation and Tilt: In the northern hemisphere, south-facing panels at a tilt angle equal to your latitude angle produce the maximum annual yield.
- Panel Degradation: Panels lose approximately 0.5–0.7% of output per year. A 25-year-old panel typically produces 80–85% of its original rating.
Calculating Solar Payback Period
Divide the total installation cost by the annual electricity savings (Annual kWh × electricity rate). A 5kWp system at $10,000 producing 6,500 kWh/year at $0.15/kWh saves $975/year — a simple payback of about 10.3 years, with 15+ years of free energy afterward.