I've got an existing 12v solar array with 1x 130 Watt and 2x 80 Watt for a total of 290 watts @ 12v, fed to a 30 amp MPPT controller (Rogue MPT-3024). I bought what I thought was going to be a 200 watt 12v panel to bring me to a total of 490 watts, which is the limit for that controller. However, the panel they shipped me is a 250 watt 24v panel. Before I go back to them to request they swap it, is there any advantage in keeping it, and using it with the 2 x 80 watt panels wired in series? This would give me 320 watts at 24V, this is where I get confused - does that give me the equivalent of 640 watts @ 12v? The controller can either 12v or 24, I think it caps out at 418 watts @ 24v to a 12v battery bank.If I really get 640 watts to the battery, I can take the unused 130v panel and give it to my dad.Thanks

If the controller handles 24v and no higher, then you'd have to run the new panel in parallel with the 2-80s (hooked in series.) Then you have a 250w panel in parallel with a "160w panel" giving you 410w. I'm not sure how you arrived at 320w. That's a big imbalance, but in parallel it just may work. I'd be willing to give it a go and see what happens. If your controller can handle more than 24v, it won't help at all because you definitely will have problems putting your new panel and the 80s in series for 48vdc. The amperage in that circuit would be severely restricted by the smaller panels. Imbalances are a big deal with series wiring.410 watts @ 24v = 17a, which theoretically pumps 34a into a 12v battery bank.phemens wrote:.. 320 watts at 24V, this is where I get confused - does that give me the equivalent of 640 watts @ 12v?No, watts stay the same (they're conserved). 320w@ 24v= 13.3a, which is 26.6amps for a 12v system. 12v * 26.6 = 320 watts.

It would actually be 130 in parallel with two 80s in series, parallel with the new 250 for a total of 540 watts.Not sure how well the power point tracking will work with the variety of panels.On edit, that won't work either because the single 130 will still be 12-volt. If you want to use the new 250 you can't use the 130. You could probably parallel everything but then you would only get half power from the 24-volt panel for a total of 415 watts (410 without the 130). I'd send it back, but shipping is a killer.

It's like taking an essay test, isn't it?

Watts are watts. Changing the voltage doesn't change the watts.I don't think you'll find a 200 watt 12 volt panel. The largest 12v panel I've ever seen was 140 watts or so.You could always add a second charge controller just for the 24v panel. Connect it in parallel with your current set up and everything will work fine.Otherwise, there is no way to use all of your current panels with your current controller.

phemens wrote:I've got an existing 12v solar array with 1x 130 Watt and 2x 80 Watt for a total of 290 watts @ 12v, fed to a 30 amp MPPT controller (Rogue MPT-3024). I bought what I thought was going to be a 200 watt 12v panel to bring me to a total of 490 watts, which is the limit for that controller. However, the panel they shipped me is a 250 watt 24v panel. Before I go back to them to request they swap it, is there any advantage in keeping it, and using it with the 2 x 80 watt panels wired in series? This would give me 320 watts at 24V, this is where I get confused - does that give me the equivalent of 640 watts @ 12v? The controller can either 12v or 24, I think it caps out at 418 watts @ 24v to a 12v battery bank.If I really get 640 watts to the battery, I can take the unused 130v panel and give it to my dad.ThanksI would advise you to "look into miss matching panels with a MPPT controller" Do your homework. If you do not your charge controller may end up being less efficient then a PWM controller.Good luck with your project!

Little confused, 12v vs. 24v solar | Good Sam Community

12thgenusa
Explorer
Oct 17, 2015
It would actually be 130 in parallel with two 80s in series, parallel with the new 250 for a total of 540 watts.

Not sure how well the power point tracking will work with the variety of panels.

On edit, that won't work either because the single 130 will still be 12-volt. If you want to use the new 250 you can't use the 130. You could probably parallel everything but then you would only get half power from the 24-volt panel for a total of 415 watts (410 without the 130). I'd send it back, but shipping is a killer.
2oldman
Explorer II
Oct 17, 2015
If the controller handles 24v and no higher, then you'd have to run the new panel in parallel with the 2-80s (hooked in series.) Then you have a 250w panel in parallel with a "160w panel" giving you 410w. I'm not sure how you arrived at 320w.

That's a big imbalance, but in parallel it just may work. I'd be willing to give it a go and see what happens. If your controller can handle more than 24v, it won't help at all because you definitely will have problems putting your new panel and the 80s in series for 48vdc. The amperage in that circuit would be severely restricted by the smaller panels. Imbalances are a big deal with series wiring.

410 watts @ 24v = 17a, which theoretically pumps 34a into a 12v battery bank.

phemens wrote:
.. 320 watts at 24V, this is where I get confused - does that give me the equivalent of 640 watts @ 12v?
No, watts stay the same (they're conserved). 320w@ 24v= 13.3a, which is 26.6amps for a 12v system. 12v * 26.6 = 320 watts.

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Little confused, 12v vs. 24v solar

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