Solar Energy Yield Calculator

How it works

1. 1Enter your solar system size in kilowatt-peak (kWp) — the rated power under standard test conditions.
2. 2Provide the average peak sun hours per day for your location and the performance ratio (typically 0.75) that accounts for inverter, temperature, soiling, and wiring losses.
3. 3The calculator multiplies these values by 365 to give annual yield in kWh, then multiplies by your grid CO₂ factor to estimate annual emissions avoided.

Use cases

• Homeowners sizing a rooftop PV system and estimating annual savings before installation.
• Energy consultants comparing expected yield across different locations or tilt angles.
• Sustainability teams reporting annual carbon offset from on-site solar generation.

Frequently asked questions

How is annual solar yield calculated?

Annual yield (kWh) = system size (kWp) × peak sun hours per day × performance ratio × 365. For example, 5 kWp × 4 h × 0.75 × 365 = 5,475 kWh per year.

What is the performance ratio and why does it matter?

The performance ratio (PR) captures real-world losses — inverter efficiency, cell temperature de-rating, soiling, shading, and wiring resistance. A PR of 0.75 is a reasonable default for most residential systems; well-maintained systems in cool climates can reach 0.80 or higher.

How do I find the peak sun hours for my location?

Peak sun hours represent the equivalent hours per day of full 1,000 W/m² irradiance. Values typically range from 2.5 h (northern Europe in winter) to 6+ h (desert regions). Databases such as PVGIS or NREL PVWatts provide location-specific data, taking tilt and azimuth into account.