Parallel 2 charge controllers

Hi Paul,

What kind of panels do you have? Who is the manufacturer and what model? What's the Voc and Isc of panel (hopefully printed on the back of the module)? Where is the array located?

Thanks!
Chris

Hi Paul,

Sorry for more questions! When you say 70 amp max, is that the max output of the solar array? How many panels do you have total? What sort of configuration do you have set up now (how many panels in series and how many series strings in parallel?)

When I size a controller I take the Isc of the array and multiply that number by 1.56. Then I find a charge controller that's larger then the number. You also might want to look into an MPPT controller so that you can go into the controller with a voltage that is higher then your battery bank and allow the controller to step down the voltage (while boosting the current). You could go into a MPPT controller with a nominal 48v and come out with a nominal 24v. Plus you will also get the added bonus of the power point tracking that will give you more energy in your batteries in lower light conditions- not to mention you will have less power loss in your transmission if your at a higher voltage.

If you're going to parallel the controllers you'll want to have the positive battery outputs and negative battery outputs of each of the controllers meet at a bus bar (or on the battery bank terminals I guess).

no, wire each array to each charge controller independently of the other.  wire each charge controller to the battery bank separately. they dont talk to each other.  they dont care what the other is doing.  each monitors battery voltage independently.  go with a c40, give yourself a little slack.

think of it as two rivers feeding one lake.

james - Alt-E staff

no that does not imbalance the banks.  you should have the bat pos and bat negative from the charge controller going to opposite diagonal polarities

for example

                       P---N/P---N
                       P---N/P---N

if this were four 6 volt batteries set up for 12v (two strings of two) you would connect the controllers at the top left positive post and the bottom right negative post to ensure correct charging.

yes you would run them to separate boxes if that were easier so long as the amperage of each array did not exceed the charge controller amperage (35 or 40 in your case)

james - Alt-E staff