Vmp and Imp calculator

Defaults: REC Alpha Pure-R 430 W class, manufacturer datasheet, US print UL EN 6.2025: Pmax 430 W, Vmp 50.5 V, Imp 8.52 A, Voc 59.7 V, Isc 8.91 A, Pmax coefficient -0.24 %/°C, Isc coefficient +0.04 %/°C, NMOT 44 °C. The datasheet prints no Vmp coefficient: -0.28 is our estimate (Pmax coefficient minus Isc coefficient). Ambient 35 °C, MPPT floor 200 V, 4 modules, 2 strings and a 20 A input limit are invented.

Ambient temperature (°C)

Irradiance (W/m²)

Modules in series

MPPT minimum voltage (V)

Strings on one input

Input operating current limit (A)

Module data (change to your datasheet)

Pmax (W)

Vmp at STC (V)

Imp at STC (A)

Voc at STC (V)

Isc at STC (A)

Pmax coefficient (%/°C)

Isc coefficient (%/°C)

Vmp coefficient used (%/°C)

NMOT (°C)

Design aid only. Check the floor, the hot design temperature and the current limit against your inverter manual and your AHJ. Cell temperature = ambient + (NMOT - 20) x irradiance / 800.