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RVing message boards => Tech Talk => Topic started by: pullinurleg on September 17, 2017, 04:27:19 PM

Title: wiring solar panels
Post by: pullinurleg on September 17, 2017, 04:27:19 PM
Hi all.
So here is my current solar configuration on top my trailer.
2- 100 w 18V 5A solar panels wired in parellel.
1- tracer 20A charge controller.
2- 6V 230 AH Batteries.

Heres my question. the wife and I are wanting to add 2 more solar panels of what we have now as far as specs go. I am thinking when i do i want to do 2 sets of 100W panels in series and then run those 2 sets parallel into the controller. Can this be done that way?
My calculations are such that each set would be 36V 5A x 2 =72 V 10A going into controller. My controller will handle 100V and 20A.

So am i correct to do it this way? Will doing the 2 sets in series then parallel into controller hurt or damage anything? Of course my numbers im figuring aren't going to be exact but gives rough figure.

I appreciate all your comments and suggestions.
Title: Re: wiring solar panels
Post by: rls7201 on September 17, 2017, 10:04:04 PM
Title: Re: wiring solar panels
Post by: Gizmo on September 18, 2017, 10:24:24 AM
A couple of thoughts, yes your calculations are correct and a 20amp CC should handle 20amp's of solar panel output.  But, I would be reluctant to max out the amps your charge controller is rated for. If it were me, I would have had a 30Amp charge controller, or only add 1-more panel.  Maybe it is just me, but I typically hate to push the limits on things electrical and mechanical for that matter.  My other thought is also a question, why not wire the additional panels in parallel as well?  Series will work, but when wired in series if at any point one of the panels is shaded, it will shut down both panels from producing power, where as in parallel you still would have one additional panel producing power.
Title: Re: wiring solar panels
Post by: Kevin Means on September 18, 2017, 11:08:06 AM
Your plan should work fine. Gizmo's correct about operating near the limits of the controller, but solar panels rarely operate at their maximum output anyway. We have three sets of series-wired panels, and the extra voltage really helps the MPPT controller with charging, but you definitely need to keep the panels out of the shade.