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RY469 · 04-11-2021, 09:48 AM

No sense getting a MPPT charge controller for such an application. Cost too much. It only comes in handy when solar panel voltage is above the 12VDC range (like multiple panels in series). Most add-on panels for the external connection on your RV are open voltage 18VDC, connected they are in the 12 - 14 VDC range (as they should be to keep batteries happy). A PWM charge controller works great with these type panels. BTW, Harbor Freight has a nice set of panels that plug right in, with controller. Keep in mind when you connect the charge controller, it is healthy (for the controller) to connect batteries first. As the output, with only solar panels connected, would be open and not good on the output circuit of the controller. I have both panels on my roof hardwired in, and a set of Harbor Freight panels I can plug in. Along with two AGM groups 31's I have over 200AH of boondocking power, and the panels do a good job of keeping up during daytime.

I'm not promoting Harbor Freight, they are just a good reference. Actually I'm an Electrical Engineer and a RV Service Technician. I also enjoy my Gulf Stream Aerolite.

PWM = Pulse Width Modulated
MPPT = Maximum Power Point Tracking

04-11-2021, 09:48 AM	#4
RY469 Senior Member Join Date: Apr 2021 Posts: 279	PWM Vs MPPT No sense getting a MPPT charge controller for such an application. Cost too much. It only comes in handy when solar panel voltage is above the 12VDC range (like multiple panels in series). Most add-on panels for the external connection on your RV are open voltage 18VDC, connected they are in the 12 - 14 VDC range (as they should be to keep batteries happy). A PWM charge controller works great with these type panels. BTW, Harbor Freight has a nice set of panels that plug right in, with controller. Keep in mind when you connect the charge controller, it is healthy (for the controller) to connect batteries first. As the output, with only solar panels connected, would be open and not good on the output circuit of the controller. I have both panels on my roof hardwired in, and a set of Harbor Freight panels I can plug in. Along with two AGM groups 31's I have over 200AH of boondocking power, and the panels do a good job of keeping up during daytime. I'm not promoting Harbor Freight, they are just a good reference. Actually I'm an Electrical Engineer and a RV Service Technician. I also enjoy my Gulf Stream Aerolite. PWM = Pulse Width Modulated MPPT = Maximum Power Point Tracking