Newbie

Riki · June 2021

I need help with what size circuit breakers go where….
i want to place
#1 circuit breaker in between my Panels (300w total) and Charge Controller (40amp)

#2 circuit breaker between charge controller (40amp) and battery (lithium 100ah)

#3 circuit breaker from battery to Inverter (200/4000w pure sine)

I am using (2) 150watt panels connected in
Parallel
vmp 18.8
imp 7.98a
voc 22.7v
isc 8.33
vmax 1000vdc

connecting to
Renogy’ 40amp charge controller
12/24v
battery current 40a
load current 20a
max battery voltage 32v
max solar input voltage 12v@520w
max solar input power 24v@1040w
Charge circuit voltage drop <100ma@12v
Discharge circuit voltage drop <0.15v

Then connecting to
lithium LiFePO4 100ah Battery

Ending at this inverter
Inverter 2000/4000w 12v
continuous power 2000w
surge 4000w
ac output voltage range 115ac
output wave pure sine
no load draw <2.1a

Thanks for the help!

mike95490 · June 2021

What i suggest, and I think is more flexible ( and useful to compare panel A vs panel B outputs

#1 circuit breaker in between panel A and Charge Controller (10amp)

#2 circuit breaker in between panel B and Charge Controller (10amp)

#3 circuit breaker between charge controller (40amp) and battery (lithium 100ah)

#4 circuit breaker from battery to Inverter (2000w run/4000w surge pure sine) 333A

So actually for #4, your inverter should specify what the value of breaker should be.
Your 100ah Li battery has a Max output amps spec, and you need to size your breaker to adhere to that spec to protect your battery. The BMS might be able to do that, but at the risk of shuttling down the battery and having to reboot the BMS

Newbie

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