₦airaland Forum

obimind:
Presently my solar charge controller is 20ah pwm and I have 4 pieces of 150 watts panel. My battery bank is 400 ah. My question is this: is my charge controller undersize?

Your 150w panels would provide a current of about 8.89A each,
if ur batteries are in series or parallels for either a 24v or 12v system, the charge controller would still be undersized.

In series (24v)
Then your panels would be connected in 2 strings, each having two panels.
8.89A(Isc) x 2 (strings) x 1.25 (safety factor) = 22.22A

In parallel (12v)
Then your panels would have to be connect in 4 strings,
8.89A(Isc) x 4 (strings) x 1.25 (safety factor) = 44.45A

you are definitely under utilizing your panels, either way so u need to upgrade your charge controller.