Little confused, 12v vs. 24v solar

[phemens]

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

[phemens]

Ok, I think (!) I'm less confused than when I started 😉 Thanks for all the opinions. The 250w 24v panel will feed the Rogue controller, I'll feed the 130w and 2x 80w 12v panels to a new Solar30, all is good.

[JiminDenver]

Search my post for the miss matched panel test. The controller certainly does get confuse, never able to settle on a voltage. Matched panels of Voc, amps AND type produce the best results.

[2oldman]

OP.. more confused?

[BFL13]

First note the voltage limit of the controller, which is the total Voc (not their Vmps!!) before choosing to put them in series at all.

[grizzzman]

brulaz wrote:

MrWizard wrote:

...
its about matching panel voltage when parallel
series panels must be identical "AMPS" so identical panels are used
parallel panels need matching "voltage for the MPPT parallel circuit input to work correctly
...

Been wondering about this. Some questions:

1) I know you want to match parallel panel voltage for best MPPT controller operation, but does it matter as much or at all for PWM?

2) For panels in series, you match amps otherwise the panel with the lowest amps (highest resistance?) limits the total current output? Or ...?

3) And that limitation for panels in series (2 above) is independent of whether you have a MPPT or PWM controller?

#1 12 volt panels are in the 17 to 18 volt range wont affect much.

#2 you need to match volts. If you use different amps the larger amp panel will only produce what the lower amp panel does.

#3 I am unsure of what you are asking but mismatch is much less of a issue with PWM.

[FlatBroke]

I hardly understood any of this. But I hate mix matching stuff. Just adds to my confusion.

[brulaz]

MrWizard wrote:

...
its about matching panel voltage when parallel
series panels must be identical "AMPS" so identical panels are used
parallel panels need matching "voltage for the MPPT parallel circuit input to work correctly
...

Been wondering about this. Some questions:

1) I know you want to match parallel panel voltage for best MPPT controller operation, but does it matter as much or at all for PWM?

2) For panels in series, you match amps otherwise the panel with the lowest amps (highest resistance?) limits the total current output? Or ...?

3) And that limitation for panels in series (2 above) is independent of whether you have a MPPT or PWM controller?

[12thgenusa]

The controller won't be confused. It will just choose a voltage that returns the highest power from the panels as a group. However that voltage will most likely not be the optimal voltage for any individual panel.

[JiminDenver]

Running mismatched panels will result in the lowest panel affecting the rest in both parallel and series.

It can also leave you with a confused controller.

I have seen larger 12v panels up to 300w, and smaller high voltage panels like the 140w 48v panels SolarBlvd.com has now.

[CJW8]

Consider getting another identical 250 watt panel and put 500 watts on your Rogue. You are in Canada and your panels are probably flat mounted so the rogue is never going to see 500 watts. Sell or give to your dad the other panels.

I am currently running 2-250 watt flat mounted panels on my Rogue MPT3024 with no issues.

[BFL13]

Give the 130w to your dad, who deserves that, and anything else he can get from his expensive- at- the- time off-spring! 🙂

Next, get a Solar30 controller for about $35 on eBay to run the two 80s in parallel, and run the 250 with the Rogue and put the Rogue and Solar30 in parallel on your battery bank.

Note that number of cells thing above.-- two 12s in series is 72 cells while your 250 is probably a 60 cell job.

[time2roll]

Sell the 12v and go all 24. Canada your panels will probably never put out max rating flat on the roof so get two more 200w and go parallel. The Rogue will limit amps to the max rating and all is fine.

[MrWizard]

simple questions

what is VMP pf the 80w panels..example 17.2
what is the VMP of the 250w panel .. example 34.5

if the toatal VMP of both 180 panels is really close to the VMP of the one 250w panel

then yes the (2) 80's series-ed together might work paralleled to the the 250

its about matching panel voltage when parallel

series panels must be identical "AMPS" so identical panels are used

parallel panels need matching "voltage for the MPPT parallel circuit input to work correctly

the max will be 410w IF it can work

you are running (3) panels parallel because the voltage is close
the 130 is odd man out in a new configuration with only one controller

like was said Maximum use, would be to replace the Rogue with a new PWM controller, and connect the NEW 250w panel with the rogue with and new wiring for the that panel
you would have two systems connected to the same batteries

that would give 310 + 250 for 560w total

[brulaz]

phemens wrote:
Ok, running 2 controllers is definetly an option, I have an older 15 amp controller still installed, that would work for the 130 watt 12 v panel. Would I be better off pairing the dual 80 watters with the 130 @ 12 v or running with the 250 watt 24v panel?

If you put the 80W panels in series, that would be the equivalent of an 80W 24V panel. If their 2 x Vmpp matched the Vmpp of the 250W 24V panel, they might work well in parallel with it and with the Rogue MPPT. But, frankly, I doubt if that's the case. I would leave the 240W 24V panel alone on the Rogue. The Rogue is an excellent MPPT controller and will do well with the 240W panel alone.

If you put the 80W panels individually in parallel with the 130W 12V panel, you will generate more power than the 15W PWM controller can handle on bright sunny days. Presumably the controller will just ignore the extra power and not burn up; that's what the Rogue does but you may want to verify it. But on cloudy, low-light days, the PWM controller will work just fine. Those are the days you really need all the solar you can get anyway. So that's what I would do.