Quote:
Originally Posted by Tronadora
I think the panels have (nearly) identical specs so isn't that OK?
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As LB3 said, as long as the specs match, while not the PERFECT setup, it will certainly work mixing the two.
I would also heed his recommendation and go with a series connection, especially since we're only talking about 3 panels total. IMO the benefits outweigh any negatives. For example, if you look at the specs of your solar charge controller, you'll see that it needs to see a certain voltage at the PV input before it turns on. If you run your panels in parallel, you won't get to that voltage outside of the 4'ish hours of midday unless you live at the equator. These panels aren't very efficient off-axis with respect to the position of the sun, and since they are mounted flat and facing straight up, their voltage output suffers. By putting them in series, you're adding the voltage from each panel to reach that magic "turn on" voltage that the controller needs to see MUCH earlier/later in the day vs. what you'd get out of a parallel config, and yes, any excess above that turn on voltage will be converted to charge current by the charge controller. The net effect is you will harvest significantly more energy with the series config, all things being equal (clouds, shade, etc). Finally, if you had 3 panels in parallel, they could produce up to 18A of current. You would be right at the edge of having to replace the wiring from the panels to the charge controller. If I remember right, it's 12AWG as it comes from the factory, and you should probably be running 10AWG at that current level. You would certainly need to swap out the fuse to a 20A vs. the existing 10A that should already be there.
I hope that helps.