String sizing for hybrid inverters: a 6-step method
By Léa Marchetti (PE, NABCEP-certified)
A worked example sizing a 5kW Victron MultiPlus-II array against the 250V MPPT envelope, the 600Voc max, and a 0.34%/°C temp-coefficient derate at altitude.
When engineering high-voltage solar arrays or selecting industrial control cable, precise datasheet derating parameters are essential to ensure NEC and IEC compliance.
1. Verification & Derating Envelope
Always verify the temperature coefficient derating (%/°C) under local ambient extreme conditions before sizing MPPT strings or conductor ampacity.