Does reverse current degrade a solar cell?

[bcroe]

That's not really a real-world situation.

What we're mainly concerned with here is shading on one or more cells creating localized hot spots, while the rest of the cells in the panel are fully illuminated.

pveducation.org has some good material on bypass diodes used to prevent this problem. Section 7.2 goes into detail and has a far better explanation than I do!

I am saying, the cells conducted just fine without sun. Like a normal diode. They don't need
sun to conduct, and I think the current flows over the whole cell surface. Or are you worried
about flow in different parts of the panel?

You could say shaded cells will conduct my heating current, and illuminated cells will conduct
my current plus that generated by the sun. I don't see that as a problem, those currents are
each only 20% the heating of full sun hitting the panel. And air will be below freezing.

Perhaps the possible hot spot effect could be set up, and a surface temperature gauge
like I have used, could check for uneven temps. I might be ready for more tests. Bruce

[PNjunction]

A test in the sun would be easy. Just make a little L-bracket out of cardboard, maybe a 3-legged plastic pizza box stiffener, and affix it to the panel to shade one cell, let it sit for a few minutes, and take a temp reading, either by probe or by handheld IR temp meter.

The pveducation.org site in section 7.2 has a nice picture of how that localized heating cracks the glass, and in some cases can desolder the tabs, etc. The animation shows it best, although it appears one has to have Adobe shockwave installed to see some of the animation.