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An MPPT controller's current rating is array power divided by battery voltage, with 25% added for irradiance above standard test conditions. Equally important is the input voltage limit: open-circuit voltage rises in cold weather, so the string Voc must be multiplied by about 1.25 before comparing with the controller's maximum.
Charge controller
I = array W / battery V, x1.25 margin; check string Voc x 1.25 against the controller input limit
Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.
Panel voltage rises as temperature falls, roughly 0.3% per degree below 25 C. On a cold clear morning Voc can exceed the rating and destroy the controller.
MPPT harvests 15-30% more energy and allows higher string voltages. PWM is only sensible for very small systems where cost dominates.