Nimesh Katariya 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%.
Why It Matters for Design Sign-Off
Temperature coefficients aren’t just a datasheet curiosity — they set the hard limits an electrical designer has to work inside. The β_Voc figure defines the cold-day ceiling that keeps string voltage under the inverter’s maximum input rating and the equipment’s DC voltage rating, while γ_Pmp shapes the hot-day power derating that a yield model has to account for. Both numbers ultimately feed the same string-sizing calculation that shows up on stamped drawings and permit packages, which is why a module swap late in a project (say, PERC to TOPCon) usually forces a re-check of string length rather than a simple like-for-like substitution.
Related Reading
Because temperature coefficients govern the cold-day and hot-day boundaries used in string sizing, they show up directly in Solar SLD software that auto-generates NEC-compliant single-line diagrams, and in the broader PV yield simulation software landscape, where γ_Pmp is one of the loss inputs behind every energy estimate. Reports that express that estimate as a confidence band — see our breakdown of P50, P90, and P99 solar yield reports — carry temperature-related uncertainty as one of their line items. For a closer look at how string voltage limits and MPPT tracking windows interact once temperature correction is applied, Qbits Energy’s guide on string voltage versus MPPT voltage in solar inverters is a useful companion read.
Frequently Asked Questions
4 commonly searched questions about Temperature Coefficient.
What is a temperature coefficient?
Typical values?
Which technologies have lower (better) temp coefficients?
How does temp coefficient affect string sizing?
Need engineering-backed solar designs?
Heaven Designs delivers PE-stamped solar design packages, structural calculations, electrical engineering, and utility-compliant permit plans.
