Solar charge controller selection help needed
I am looking to put in a solar system that will produce about 30 amps per day. I choose a semi-flexible 135 watt panel made by Sunpower which meets my capacity needs. My only problem is choosing t...
Forum Discussion
scrubjaysnest wrote:
Per NEC for 30 amps of solar you will need a 45 amp controller; NEC derates them to about 36 amps. Our worst case boondocking usage takes the batteries to 47% state of charge in one day. That is ~662 WH. We are very conservative and normal usage is ~189 WH. A quick and dirty rule of thumb 100 watts of solar per 100AH of battery, but the reality is more complicated.
MorningStar Corp says no need to derate their charge controllers. They will shutdown if too much current, heat, low voltage, etc. They also already factor in a fudge factor.
More details here: http://www.solardirect.com/pv/controllers/prostar.htm
I'm using two of their Prostar 30M controllers, and a Morningstar Sunsaver 10L. Excellent products.
