Temperature-Corrected Voc/Vmp · MPPT Range Check
Calculate cold-corrected string open-circuit voltage (Voc) and hot-corrected string maximum power voltage (Vmp) for a solar PV string, based on module datasheet temperature coefficients and site design temperatures. This is essential to verify a string configuration will not exceed inverter maximum DC voltage on cold mornings, and will remain within the inverter's MPPT operating range on hot afternoons.
Results for guidance only. Verify against current standards and manufacturer data.
Not a substitute for engineering judgement or a licensed professional.
Module Voc increases as temperature drops below the 25°C STC rating (using the module's negative temperature coefficient), so the coldest expected site temperature determines worst-case string voltage — this must not exceed inverter maximum DC input voltage. Conversely, Vmp decreases as module temperature rises above 25°C, so the hottest expected module temperature determines the worst-case low string voltage — this must remain above the inverter's MPPT minimum voltage for the inverter to track the array's maximum power point. Vmp also has a negative temperature coefficient, so it RISES in cold conditions: the MPPT maximum check therefore uses cold-corrected Vmp, not STC Vmp. Using the STC value here would understate the worst case and could pass a string that actually exceeds the tracker's upper limit on a cold morning. All four voltages — cold Voc, cold Vmp, STC Vmp and hot Vmp — are shown so each check can be traced to the condition it represents.