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Solar Panels different sizes connected

RanVan

New Member
Joined
May 13, 2021
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I am upgrading my old offgrid 12V lead acid system to a 24V LiFePo4. My old system ran on a single 190W solar panel. I have purchased 3 x 440W panels (49.9V OC and 9.65A Max) and and they will be hooked up to an MPP All-in-One Inverter/Charger/Charge Controller. I was going to hook up all 4 panels (even though I don't need all the power) by putting 2 of the 440W panels in parallel and the 190W and 440W in parallel and then hook the two banks up in series. It looks like this is a bad idea. Should I just sell the 190W and then put the remaining 3 x 440W panels in series?
 
If I put the 3 panels in series I assume that would be too much voltage for the MPP 2024 (max input VOC is 145V). I have ordered a 4th panel to go with 2S2P array. In the meantime should I just hook up 2 of the panels in series and wait for the 4th panel, or could I hook up 2 in parallel and then put the 3rd in series with those?
 
Just make sure each string has the same total voltage and you don't exceed the controller rating with total VOC.

You can't really match two strings with 3 panels however unless the odd panel out happens to have the same voltage as the two in series do when combined.
 
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