Odd paralleled string of pv

[Supervstech]

I am wondering if an odd arrangement of panels will work .
I'm thinking of like 5S and two more added parralel..parallel...
So let's say I have seven 240W panels. I tie two pairs together parallel, then tie those to three more in series.
Will it output more watts than 5s?
Will it catch fire?
Will it do less watts? Will it make no difference?
I will be setting up an experiment, anybody wanna make predictions?

 

[Bobert]

I wonder if un fused the panels would have a greater chance of catching on fire if one shorted out compared with a standard configuration. This is an unlikely thing in any case and probably not a factor for an experiment. .My prediction is that you will have lower watts because none of the panels will be able to function at maximum power point. I’m guessing that in full sun disconnecting the parallel pair may actually increase your wattage. This is assuming that you are using a MPPT charge controller.

 

[chrisski]

In my signature block, there is some math one can use to figure out their circumstances. It’d be interesting to see if its right..

My bet is the with five in series in parallel with two in series, the output is dragged way town to 2s2p worth of output. so barring any shading that would be less than 5s.

EDIT: O Reginald response changed to match predictions or experiment.

 

[fat_old_sun]

I am wondering if an odd arrangement of panels will work .
I'm thinking of like 5S and two more added parralel..parallel...
So let's say I have seven 240W panels. I tie two pairs together parallel, then tie those to three more in series.
Will it output more watts than 5s?
Will it catch fire?
Will it do less watts? Will it make no difference?
I will be setting up an experiment, anybody wanna make predictions?

Your string will behave like a 4S, with a current of one panel & 4X voltage of a single panel. The two panels that are connected in parallel will be producing approx 50% of their rated power.

 

[Supervstech]

Just to clarify, I am parraleling two panels with two in the 5S string...
So it would be 5S with two of the 5 having an additional panel on them.

I invision the two extra panels will add wattage to the string.
Maybe not much, but more than 5S alone.
It will take me a lot of time to configure this for the test,and I will need to gather a few weeks worth of data both ways to see...

 

[chrisski]

I’m changing my guess all seven panels output to 5s, but that’s only what the math in my signature block article is telling me. I’ve got my suspicions about that article.

 

[fat_old_sun]

I misunderstood the configuration.
The output will be exactly that of a simple five panels in series. The current in a series circuit will be limited to the current of the weakest panel; since the panels are identical, the current will be that of a single panel. The voltage will add up.

 

[Supervstech]

I misunderstood the configuration.
The output will be exactly that of a simple five panels in series. The current in a series circuit will be limited to the current of the weakest panel; since the panels are identical, the current will be that of a single panel. The voltage will add up.

That is what I expected, but with any shading issues, on the two doubled panels overall I think there might be more output.

 

[fat_old_sun]

That is what I expected, but with any shading issues, on the two doubled panels overall I think there might be more output.

The output will still be the same, since the current is limited by single panels. This is a lot like a long single lane road that has a short segment of two lanes; the max traffic is determined by the single lane section.

 

[Hedges]

Unfortunately, current won't be limited to single panels.
If shade falls on the three single, or if shade on two single and you have a good enough MPPT that it recognizes 2p2s is better than 3s, you get 2x Imp pushed through bypass diodes. They overheat and melt/crack things.
Since this is to be a live experiment, can we get a video of the damage? Top and bottom?

3s2p might be your best bet.