Determining The Correct Size Solar Charge Controller For Four 100w Solar Panels

Updated 02/20/2023 | Published 02/18/2023

Question:

I currently have a go power charge controller pwm-10-SQ and want to upgrade it to your item number 34276119. I have a factory mounted 100 watt solar panel on the roof of my rv and would like to know if the inverter I have will work as is until I get it upgraded at a later date. I am buying a 12v/100amh lithium battery and later would like to add 3 more 100 watt solar panels. Thank you for your time. Waiting on your response to pull trigger

asked by: Don W

Expert Reply:

The inverter is simply pulling battery power and converting it to AC current to power appliances for your trailer and wouldn't be a factor in the amount of solar panels you have other than possibly needing more panels to recharge the amount of power the inverter is using up.

As for the charge controller, the # 34276119 has a 30 amp maximum so you'll need to determine the amount of panels that it can manage. This is done by dividing the wattage by the voltage and adding in an extra 25% for surges. If we divide your 100w panel by 12v we get 8.33 + 25% = 10.41 amps so you'd only be able to add on one more 100w panel to the charge controller to stay within the safe zone of the controller.

You would need a larger amperage controller like the Go Power MPPT Solar Charge Controller # GP54FR to be able to handle four 100w panels.

expert reply by: Kevin C