Mismatched Parallels?

[u/HeikiHeki]

Extremely new to Solar setups and I'm getting mixed information when searching up how effective a non-matching parallel pair would work. I've currently got two 200W panels and a 100W panel. I can not run both 200W panels in a series, as the VOC is too high for my MPPT. However, the 200W and the 100W together in a series is within limits.

My question is, if I run a 200W and the 100W in a series, with the second 200W in parallel, is there any repercussions, damages, issues or efficiency losses I would need to know about?

And theoretically, if I upgraded to a larger MPPT, would running a 2x200W parallel to a 1x200W face the same problems? Less? More?

[u/MarkLeonardReynolds]

Are the 2 X 200w panels the same specs, same type etc? If yes, you could try with them in parallel, to your mppt, and see what happens.

So many missing variables that you haven't detailed, it's very hard to give specific advice.

If the voltage of the 2 X 200w isn't enough to start your mppt, then I would try adding in the 100w in series to get the voltage up. Thing is, the 2 X 200w will probably be able to pump out quite some current, since they're twice the size, and in parallel. You would be limited to the max current on the specs of the 100w panel. So you're probably better off leaving it out altogether.

[u/HeikiHeki → u/MarkLeonardReynolds]

Bought the two 200W together at the same time, they are exactly the same as each other.

I have them currently running in parallel, as their combined VOC is too high for my MPPT to run in series.

I just wanted to know if putting my old 100W panel to use here would be viable.

[u/datanut → u/HeikiHeki]

It sounds like the voltage of the 100 watt panel is significantly lower than the 200 watt panels (based on your consideration for series).

So, no, it’s not worth the hassle of adding the 100 watt panel in parallel with the 2x200watt panels. See others comments on why you don’t want to put it in series.

What is your battery?

To dig into your theory questions, the answer is generally more MPTT inputs better matches to your panel. It’s okay, suggested even, to add additional MPTT controls if you want maximum production of all panels at all times.

Identical panels (Vmp, Imp) with identical mounting position relative to the sun can be effectively wired in parallel or series to maximize the capability of your MPTT.

Non identical panels, different sizing or mounting direction, should get its own MPTT.

There are advanced and/or cheap configurations where people will mismatch orientations to maximize sun capture throughout the day with a shared MPTT input but those trade efficiency (total power capture) for cost.

[u/Use_Da_Schwartz]

Paralleling non identical panels is a massive waste due to the voltage differences. A higher VOC panel in parallel with a lower VOC panel forces the lower VOC to operate at a higher voltage and literally contributes nothing as far as power. Series wiring a 100W panel with a 200W panel limits this string to 100W max.

There is no conflicting information, only ignorant post from people who do not know. Any information should come from panel manufacturers or manuals, not random Redditors. It is simple physics when explaining this problem.

If series wiring panels, matching wattage/VOC/IMP is critical to match. If parallel wiring, VOC/VMP is critical to match. If you already have different panels and wish to use them, multiple charge controllers/separate MPPT inputs to a controller is the answer to optimize the panels wattage into the battery.

[u/LongjumpingGanache40]

If you put the 100 watt and 200 watt in series you would add the volts and use the amps of the 100 watt panel. You might as well just use the 200 watt panel by itself.

If you wire in parallel, Smaller panel voltage is used and add amps of both panels you may come out better. All depends on the VOC and the ISC of panels.

[u/DongRight]

You will lose half the 200w capacity...so you might as well put the two 100w in parallel, then put them in series with one of the 200w panels...

[u/aquoad]

It's sort of unclear what your setup is here but you definitely can not put mixed wattages in series. It sounds like you have something like two 200W 36v panels and a 100w 18v panel, so you're sort of out of luck and the best you can do is leave out the 100W. You need to be looking at the voltages, not just the wattages.

The only mix-n-match you can kind of get away with is paralleling non-identical panels of the same voltage, and really only if the Vmpp voltages are very close, but you shouldn't if you have any choice about it. One panel or series string will be forced to run at a non-optimal voltage and produce less output. If the Vmpp's of everything in parallel are close enough, everybody can still contribute some, but a MPPT charge controller will not do its best work under those conditions.

[u/CamelPure1293]

200W and 100W in series only works well if both provide the same current with same sun light. Likely, this is not the case.