Temperature coefficient quantifies how photovoltaic module performance changes with each degree Celsius of cell temperature variation. Separate coefficients exist for voltage, current, and power, with power coefficient averaging -0.40 to -0.50%/°C for crystalline silicon modules.
Individual Parameter Coefficients
Open circuit voltage decreases approximately -0.30%/°C, making cold weather beneficial for voltage stability in strings. Short circuit current increases about +0.06%/°C with heat. Power output decreases -0.40%/°C overall, meaning a 350W module rated at 25°C produces only about 322W at 45°C. Temperature coefficients vary by technology—thin-film modules sometimes show -0.25%/°C, while high-efficiency multi-junction cells may reach -0.35%/°C.
System Design Application
Installers use temperature coefficients to predict seasonal and climate-specific performance. Hot climates with frequent 50°C+ cell temperatures experience 20-30% summer output reduction compared to cooler regions. NEC 690.7(A) requires using maximum OCV calculations at minimum expected temperatures to ensure inverter voltage ratings remain within limits. Energy modeling software incorporates temperature coefficients to produce realistic performance predictions based on local climate data.