About the Temperature Loss

Temperature loss (or temperature coefficient loss) is the reduction in solar panel output at high cell temperatures. All PV cells produce less power when hot — a monocrystalline panel typically loses 0.3–0.4% of its output per °C above 25°C (STC). India's summer temperatures regularly push cell temperatures to 55–75°C, causing 10–20% instantaneous power loss.

Formula

How to calculate it

1. 1Find the panel's temperature coefficient (γ) from the datasheet — usually listed as %/°C for Pmax.
2. 2Estimate operating cell temperature: Ambient + (NOCT − 20) × G/800.
3. 3Apply the temperature derating formula to get actual power at the operating temperature.
4. 4For annual energy models, use hourly TMY (Typical Meteorological Year) data to compute weighted-average temperature loss.

Worked example

A 400 W panel (γ = −0.38%/°C) on a 42°C ambient day in Delhi with full sun (1000 W/m²). Cell temp = 42 + (44 − 20) × 1000/800 = 42 + 30 = 72°C. Derating = 1 + (−0.0038 × (72 − 25)) = 1 − 0.179 = 0.821. Actual power = 400 × 0.821 = 328 W — an 18% loss at that moment.

What you can calculate

• NOCT model
• Pmax coeff
• Cell temp
• Module tech comparison

Key definitions

Definitions from the SolarPedia glossary

Frequently asked questions