Mismatched Solar Panels – What happens? 200W 24V with a 50W 12V

Hi, I'm Amy from the altE Store. I was recently
asked a question of someone who had a 200W 24V solar panel, going through an MPPT charge
controller, to a 12V battery. They actually asked me, could they add a 50W 12V panel,
just to get a little bit extra power. So, I figured we'd take a look. It is after 5:00,
so I'm not getting the maximum power I can out of these, so that'll explain why the current
isn't as great as it could be. But, so we've got this 24V 200W solar panel going through
the MPPT to the battery, and it's reading 6.22A. I'm going to write that down (6.22A).
Now I'm going to disconnect that, and I am going to connect the 50W 12V panel and see
what we get from that. This isn't how you would normally connect them, but just for
demo purposes, I'm just using this coupler. OK so now I've got just the 50W solar panel
connected, and I'm reading 2.26A, I'm going to write that down (2.26A). Now if I were
to connect them all together in parallel, if there were to be truly accumulative, I
would expect to see about 8 1/2 amps when I put them in parallel.

So let's see what
we get. This will be fun. I've got the two of them wired in parallel, I'm going to turn
on the charge controller, and turn on the input into the charge controller and let's
take a look at what we've got. So remember we had 6.22A with just the 200W 24V, we
had 2.26A with just the 50W 12V. Together, we've got 6.6A. So, wow, it only added about
.4A to put those together. What's happening is the MPPT charge controller is just really
not happy with such a crazy mish mash of solar panels. Having both a different current and
a different voltage is just, it's not able to do the maximum power point tracking.

And
we've got one panel pulling down the other panel. It's just a mess. So I would say this
would be a definite no, don't do that. Let's try now, wiring the two of them in series
and see what we get with that. So we'll have a total of 36V nominal in, and see what happens
with that. OK, so I've got these two wired in series, so I've got basically 36V going
in, and then I've got 12V coming out. So again, let's see if we get a combination of the two
of them. The MPPT's just going through it's little thing. Ahhh! I've got 7A now. So it's
still not as good as the 8 1/2A, but, I'm getting better results wiring the two mismatched
voltages in series, and then putting them down through the MPPT charge controller, down
tot he 12V out. Interesting. I hope you found this interesting. If so, give us a like and
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