Cell Temperature
The operating temperature of solar cells under sunlight, typically 20-40 degrees Celsius above ambient temperature. Higher cell temperatures reduce voltage and power output.
Why It Matters
A panel rated at 400W produces that power at 25 degrees C. On a 35 degrees C day, cell temps reach 55-65 degrees C, reducing output by 8-15%. This is why solar production dips in extreme heat.
Related Terms
Temperature Coefficient
The rate at which a solar panel's power output changes with temperature, expressed as %/°C. A typical coefficient is -0.3% to -0.4% per °C — meaning output decreases as panels get hotter.
Standard Test Conditions (STC)
The standardized laboratory conditions under which solar panels are rated: 1,000 W/m² irradiance, 25°C cell temperature, and AM 1.5 spectrum. Panel wattage ratings are always at STC.