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gasnet avatar image
gasnet asked

mppt upgrade 75/15 to 100/20

2 170 watt panels in series 110ah 12volt bank. With my 75/15 mppt on sunny day i show average of 44 volts 6 amps on pv array and 15 amps (max for my controller)battery charging. Would upgrading to 100/20 yield anything better? If i can get max 20 amps it would it be worth it. For test purpose i drain battery to 11.80 then activate pv breaker at noon.My panels are rated at 9 amps and only getting 6 so perhaps its got a little more power with an upgrade. Also using 10 amp blade fuse on pv array but fuse is rated at only 36 volt max. Ordered optifuse apr58 10amp fuse rated at 58 volts . Thoughts on pv fuse and if its really necessary? Seems like bottle neck to me after running 75ft of 7 awg pv wire.

MPPT Controllers
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ejrossouw avatar image ejrossouw commented ·

A couple of observations. You get specific DC fuses for the PV. Worth exploring those as they are typically rated 600V or above and designed for the purpose. Secondly, 240W / 14.6V = 16.4A which is your panel rating but your numbers suggest 264W. Not sure what the duration of this output is but that makes it about 18A so maybe on this helps with that question.

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

https://www.victronenergy.com/mppt-calculator

Even the 100/20 can get to it's limit under good conditions.

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porcini avatar image
porcini answered ·

Yes, you will come close to 20A at good conditions for a couple of hours. But with a small battery like you have it, an upgrade wouldn't be that profitable.

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