Connecting two solar panels to a single charge controller

6 Posts
Mar 11, 2009 01:53 am
Connecting two solar panels to a single charge controller

Is is possible to connect 2 solar panels to a  30A charge controller.

The Solar panels are both 12 but one is 80W and the other is 120W. They are of different brands, but will be mounted in the same direction.

Can I just parallel wire these panels to the charger, or do I need to use blocking diodes on both panels?
2 Posts
Mar 16, 2009 10:00 pm
Re: Connecting two solar panels to a single charge controller

You will need to check the voltage and current ratings on the panels.  If their voltage ratings are close, which for 12V panels they probably are, then you can wire them in parallel and their current output will be additive.

Yes, you should use blocking diodes, but download and read the manufacturers installation sheets to see how.  Most panels have the diodes built in, or pre-installed in the wiring box.
578 Posts
Mar 17, 2009 11:56 am
Re: Connecting two solar panels to a single charge controller

yes, you can connect two modules (of the same nominal voltage) in parallel to one controller.

no, blocking diodes will not be necesary.�  the charge controller will provide that function, and the series overcurrent protection in the combiner box will further protect the modules, provided the overcurrent protection is sized appropriately to the max series fuse size of each module.

to do it properly, a combiner box with appropriate series string protection would be the way to go.�  this box would go next to the modules and allow you to leave the array with one positive (ungrounded-red-), one negative (grounded-white-), and one equipment grounding (green) that would go to your pv disconnect then charge controller.

here is a schematic from a package of a system that is likely similar to yours (at least the array with two modules in parallel).�  to see the schematic, scroll down to a picture of a cabin and click on it.


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« Last Edit: Mar 17, 2009 12:00 pm by James Cormican »

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