Parallel Panels and Shading versus Series Parallel

chrisski

Photon Sorcerer
I tested some panels for output today when shaded.

2 Panels in Parallel (36 Cells Per Panel)
-One panels with only 2 cells shaded 26% Reduction in Wattage
-One Panel 50% shaded 54% Reduction in Wattage

3 Panels in Series (33 Cells Per Panel)
-One panel Two cells Shaded 33%-50% Reduction in Wattage
-One Panel 50% Shaded 69% Reduction in Wattage
-One Panel 70% Shaded 88% Reduction in Wattage
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This is by no means a scientific study. It helps me realize how much power I can be losing for obstructions. Panels are going to get put up with whatever jigsaw puzzle you have based off roofspace and vents and Air Conditioners, etc.
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Data for Parallel Panels:
1627849253054.png
1627849394397.png
Data For Series Panels:
1627849294583.png
1627849309463.png
1627849352000.png
1627849480637.png
 

wattmatters

Solar Addict
This is by no means a scientific study. It helps me realize how much power I can be losing for obstructions.
Depending on panels, they may be divided in sections each with bypass diode, e.g. my home solar panels have 3 bypass diodes. So if shade is cast across cells only in a section covered by one diode, the other two sections can still supply reasonable power and output is reduced by roughly 1/3rd. But if the shading cuts across all three sections even if the total shading is only covering 1/3rd of total panel area, it will drop output of the whole panel dramatically. Indeed it will drop output for the whole string significantly.

Partial shading for string arrays sucks. Transient shade is fine, they are designed to cope with that but any form of long term shade on a part of a panel is bad for the panel's long term health. Lichen growth is an example.
 

Swamplizard

Ready to unplug and wander the USA
Thanks really good info ... I will try to reconfigure. Probably get more power out of two panels serial without shade than three with shaded 1/3 on one panel and just duplicate it on passenger side of the RV roof.
 
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