Solar panel configuration: 2s3p VS 3p2s

[rloveless]

The below diagram shows a 2s3p & 3p2s solar configuration respectively(at least I think that's what the configurations are called). I wired my 6 solar panels using the bottom example(3p2s) but afterwards I realized that I could wire them in a 2s3p configuration(top example).

Are these pretty much the same? Is there any benefit of going with one configuration over the other?

After reading this blog I believe both configurations need to be fused where the 3 hot lines come together. So the top example would need fewer fuses.

Otherwise, I think they're pretty much the same and will preform the same in shady conditions. Am I missing anything? Thanks.



Each panel is 240w. 38voc, 8a. 15a max fuse rating"

 

[SamDeleted]

Am I missing anything? Thanks.

Yea you've pretty much got it , but what your post missing is the specs of your panels and MPPT !! lmao ?

 

[rloveless]

Yea you've pretty much got it , but what your post missing is the specs of your panels and MPPT !! lmao ?

I updated the panel info. I didn't think it was relevant.

 

[SamDeleted]

I updated the panel info. I didn't think it was relevant.

Yes it's absolutely relevant, also need the mppt model / specs ( max PV voltage/mppt start up) if you can pls

 

[SamDeleted]

The best way to wire up the panels depends on their specs and your MPPTs specs

 

[rloveless]

The best way to wire up the panels depends on their specs and your MPPTs specs

i'm not asking what the best way to wire up 6 panels is. i'm asking specifically if there's a difference between these 2s3p and 3p2s. pros and cons of one or the other.

 

[rloveless]

Yea you've pretty much got it , but what your post missing is the specs of your panels and MPPT !! lmao ?

Also, please be respectful on these forums.

 

[MrM1]

i'm not asking what the best way to wire up 6 panels is. i'm asking specifically if there's a difference between these 2s3p and 3p2s. pros and cons of one or the other.

3p should probably be fused at each string

 

[Rednecktek]

2s3p -
Pro's: Handles shading better if 1 panel gets covered (each string acts as a single panel, so if 1 panel is shaded you still have 4 panels performing normally)
Con's: Requires 3 fuses or combiner box, at 24a requires at least 10AWG wire, more joints means more points of failure

3s2p -
Pro's: Can charge under lower light conditions for longer in the day, requires no fuses, less wire involved overall, can use thinner wire (16a is 12AWG), less points of failure at the connectors
Con's: More affected by shade (if 1 panel is shaded, only 3 panels operate normally), requires an SCC capable of 150VoC which are more expensive,

Either Way: you'll want a fuse or breaker coming into and out of the SCC, but if you go 3p a combiner box will be the easiest option. The potential wattage total will be the same, it's more about simplicity VS shading protection.

 

[SamDeleted]

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[SamDeleted]

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[timselectric]

In general. We put panels in series strings to create the desired system voltage. And then put strings in parallel to get the desired amperage.
2s3p is the normal setup. 3 fuses required.

3p2s requires 6 fuses. And is more problematic.
Any failure becomes a cascading failure event.
If one panel fails in a 3p2s configuration. The other two are forced to carry the full amperage of the other 3p set. This situation could easily go unnoticed, and degrade the remaining two panels. As it would still be below the panels OCP rating. But above the normal operating current.

 

[RKDowner]

i'm not asking what the best way to wire up 6 panels is. i'm asking specifically if there's a difference between these 2s3p and 3p2s. pros and cons of one or the other.

2s3p and 3p2s give the same voltage and current to the SCC. Some people apparently are confused and think you mean 3s2p when you clearly said 3p2s.

I'm going with 3p2s for my installation even though it increases the initial cost. You need reverse blocking diodes so that if a shadow falls on a panel the others don't try to back feed it. This means that panel is not contributing at all. With 3p2s just that one panel is out, leaving five still working. With 2s3p both panels in the pair are out, leaving only four still working. 3p2s needs six diodes and fuses instead of three, but in my opinion it's worth it.

As timselectric pointed out, you now have two and three, not three and three, so the two carry the current of the three, which is a consideration. If you're in Arizona it could be an issue. I'm in the PNW and the panels are flat on the roof, not tilted up to the sun, so I'm not worried about it; I doubt I'll get 80% out of my panels in the best conditions. My panels are rated at 6.2 amps. 6.2 x 3 / 2 = 9.3 amps per remaining panel in that scenario, and they're internally fused at 15 amps. 6.2 (from the remaining panel) + 9.3 (from the other panels) = 15.5 amps, so yeah I'm pushing it, but at 80% it's now 12.4 amps, so I'm not worried. You should do the math on your own panels before you decide.

timselectric please correct me if I'm wrong.

 

[crossy]

2s3p and 3p2s give the same voltage and current to the SCC. Some people apparently are confused and think you mean 3s2p when you clearly said 3p2s.

Yeah, I was one of the confused, the diagrams confirm. I think the issue is that 3P2S would be an unusual configuration.

I would go for 2S3P, fewer fuses required (3 vs 6) although, if the SCC was capable, I'd go 3S2P, no fuses and smaller wiring.

My rule would always be to make the parallel connection "last" i.e. as close to the SCC as possible.

 

[timselectric]

2s3p and 3p2s give the same voltage and current to the SCC. Some people apparently are confused and think you mean 3s2p when you clearly said 3p2s.

I'm going with 3p2s for my installation even though it increases the initial cost. You need reverse blocking diodes so that if a shadow falls on a panel the others don't try to back feed it. This means that panel is not contributing at all. With 3p2s just that one panel is out, leaving five still working. With 2s3p both panels in the pair are out, leaving only four still working. 3p2s needs six diodes and fuses instead of three, but in my opinion it's worth it.

As timselectric pointed out, you now have two and three, not three and three, so the two carry the current of the three, which is a consideration. If you're in Arizona it could be an issue. I'm in the PNW and the panels are flat on the roof, not tilted up to the sun, so I'm not worried about it; I doubt I'll get 80% out of my panels in the best conditions. My panels are rated at 6.2 amps. 6.2 x 3 / 2 = 9.3 amps per remaining panel in that scenario, and they're internally fused at 15 amps. 6.2 (from the remaining panel) + 9.3 (from the other panels) = 15.5 amps, so yeah I'm pushing it, but at 80% it's now 12.4 amps, so I'm not worried. You should do the math on your own panels before you decide.

timselectric please correct me if I'm wrong.

You're not wrong.
3p2s will be the same as 2s3p for the SCC. As long as everything is working correctly. And it may be better in shady conditions. But I don't know if it is worth it for the extra effort and added complexity.
I prefer to keep things as simple as possible. Every connection point is a possible failure point. And every fuse or diode adds another connection point (or more) .
IMHO
The most optimal configuration is ?s2p.

 

[ksmithaz1]

I think you are overthinking it with only 6 panels. If you get to 16 panels in multiple locations then you may want to start tweaking and combining strings to prevent shading issues. For a 48v battery setup, you would likely want 2 strings of 3 panels on 2 MPPT's and then just call it a day. 120VOC should be able to reliably feed 48v from a 150pv/10A MPPT. 120VOC is probably going to get you ~70-80V working. If you are charging 12v batteries then you can get by with a lower voltage/more parallel configuration, as far as combining 2 sets of 3 vs 3 sets of 2 see timselectric's comments. Either way that's only a 76VOC, and your going to want 57v to charge 48v batteries and I'd make an even money bet there will not be a 5% difference in total output either way under varying conditions. The application matters foremost, then configure the strings to meet the demands of the application.