Builiding of a complete 6kW PV inverter with MPPT chargers

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Joined: 17/10/2017
Location: Belgium
Posts: 437
Posted: 08:26am 30 Apr 2024      

The higher the input/output ratio the more stress for the diodes.

I've run the mppt at 100A charging current limit for years with irfp4110/30cpq100 combo, 2 each, and forced cooling.
This was only with 60-62V nominal in and 52-54V out, so high dutcycles.

I did had a MOSFET blowup but I suspect actually a PCB fault because of moist and dust build up close to the gate. The board was exposed to my basement environment, allthoug not that bad, but you could see a lot of coroded spots on the PCB.
The board transferred 15000kWh of energy before 1 MOSFET failed.

I'm now running the same setup(silicon) with newer panels but current is devided over 3 boards now with max of 55A charging current, with 78V in and 52V-55V out. I feel I need to switch to 150V devices but the hardest stressed board did 1100kwh now.