Solar Panels and shading - combined Series & Parallel


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Travis Watson

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Aug 6, 2017
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Apologies if this has been discussed, but I could only find relevant discussion for batteries.

But this is about solar panels!

I've seen that shading on a single solar panel can knock out the entire series string, and that's one of the benefits of parallel. However the higher voltage also has its benefits too.

So many combinethe two. But every time I've see them combined, it's series first, then parallel like so:


image_lauprb.jpg


My question is -- why series-first? Wouldn't parallel-first give you more of that shade-resistance effect while giving the same high voltage output? What am I missing?
 

Korishan

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It's been discussed here what to do for shading: http://secondlifestorage.com/t-Diodes-matrixing-and-shading

You can get the best of both worlds with the matrices. You can also go as far as diodeing the panels so that if a cell in panel get blocked, it can bypass that cell and not effect the rest of the panel. Or do it to a string of cells. Usually the panels are built with series of cells going the length of the panel, then the series strings are paralleled at the ends on the busbars.
 

Travis Watson

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Korishan said:
It's been discussed here what to do for shading: http://secondlifestorage.com/t-Diodes-matrixing-and-shading

You can get the best of both worlds with the matrices. You can also go as far as diodeing the panels so that if a cell in panel get blocked, it can bypass that cell and not effect the rest of the panel. Or do it to a string of cells. Usually the panels are built with series of cells going the length of the panel, then the series strings are paralleled at the ends on the busbars.

Spot freaking on!! That's exactlywhat I was after, this video is gold:

And he basically says exactly what I'm asking... instead of doing 3S3P, do 3P3S. A bit more complex wiring, sure, but it's really nice to see I'm not so crazy.

Thanks Korishan!!
 

Korishan

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Now don't forget, you need to use diodes to keep the power flowing correctly in that configuration. Make sure you get some beefy solar rated diodes. They are designed to have the least amount drop out voltage.
 

KtB

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Korishan said:
Now don't forget, you need to use diodes to keep the power flowing correctly in that configuration. Make sure you get some beefy solar rated diodes. They are designed to have the least amount drop out voltage.

Another option although there is some cost involved is to use Tigo optimisers. I got some cheep of eBay with the controllerand they are brilliant at dealing with shading in any configuration.
 

Korishan

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Yeah, we talked about microinverters in another thread (i started it a month or so ago). It wasn't talked about much. Altho, i was talkin more of making the inverter ourselves, rather than buying a premade system.
 

KtB

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Korishan said:
Yeah, we talked about microinverters in another thread (i started it a month or so ago). It wasn't talked about much. Altho, i was talkin more of making the inverter ourselves, rather than buying a premade system.

Just to clarify these are not inverters but more an impedance matching system with the ability to bypass a panel if it starts to drag down the string voltage Therefor enabling you to have panels pointing in lots of not ideal directions.
 

Korishan

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Oooohhh, now that is a difference. My apologies. I didn't realize there was such a beast. So if the panel can't keep up with the rest of the cells (or more so, it wants to "draw" energy), it gets disconnected until it's condition improves.
Interesting...Very very Interesting....
 
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