Definition
Temperature coefficients are the percentage change per °C of a PV module's electrical parameters — Voc, Vmp, Isc, Imp, and Pmax. They quantify how module performance varies between cold and hot operating conditions.
Module Temperature Coefficients (Typical 2024)
| Technology | β_Voc (%/°C) | γ_Pmp (%/°C) |
|---|---|---|
| PERC | −0.27 to −0.30 | −0.35 to −0.40 |
| TOPCon | −0.25 to −0.27 | −0.30 to −0.34 |
| HJT | −0.22 to −0.25 | −0.24 to −0.28 |
Application — Voc Correction
Voc(T) = Voc(STC) × [1 + β_Voc × (T − 25)]At T = −10°C with β_Voc = −0.0027/°C: Voc rises ~9.5%.
Key Takeaways
- Temperature coefficients quantify module response to cell temperature change.
- β_Voc and γ_Pmp drive cold/hot-day calculations.
- TOPCon and HJT have tighter (better) γ_Pmp than PERC.
- Always temperature-correct using site-specific cold and hot temperatures.
- Datasheet values are nominal; field variation 5–10%.
Frequently Asked Questions
4 commonly searched questions about Temperature Coefficient.
What is a temperature coefficient?
The fractional change in a module electrical parameter per °C of cell temperature change from STC (25°C).
Typical values?
β_Voc: −0.25 to −0.30 %/°C. β_Vmp: −0.30 to −0.40 %/°C. α_Isc: +0.04 to +0.06 %/°C. γ_Pmp: −0.30 to −0.40 %/°C.
Which technologies have lower (better) temp coefficients?
TOPCon and HJT have less negative γ_Pmp than PERC. HJT γ ≈ −0.26 %/°C vs. PERC −0.35 to −0.40 %/°C. Critical advantage in hot climates.
How does temp coefficient affect string sizing?
β_Voc determines cold-day Voc upper bound. β_Vmp determines hot-day Vmp lower bound. Tighter (less negative) coefficients allow longer strings.
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