Solar Panel Shading

[nwdiver]

We had snow for the first time since I was able to monitor a system with module level monitoring. Since the previous discussion regarding optimizers vs bypass diodes is buried in an unrelated thread and there appears to be a TON of confusion around this issue I thought a dedicated thread might be a good idea.

Pretty clear that complete shading on a few panels in a string does not kill the string without optimizers. Indeed very little production is lost. The top and bottom rows are separate strings. Snow is still covering all but the 5 panels in the upper left, the panels in the upper right is 2/3 covered. Current is able to shunt around the covered panels via the bypass diodes.

The panel with a yellow label is equipped with an optimizer... it's clear that it's not helping.

 

[S'toon]

This is something I've been keenly interested in. How well do solar panels cope with snow. I've read that the snow quickly melts and slides off panels, even in cold conditions. Don't know how true that is.

 

[nwdiver]

This is something I've been keenly interested in. How well do solar panels cope with snow. I've read that the snow quickly melts and slides off panels, even in cold conditions. Don't know how true that is.

It depends. The bottom row of this array is still partially covered in snow but the array is only ~23 degrees. If you're in an area that gets a lot of snow I think the best course is a ground mount that's at least 30 degrees. But it doesn't take much snow to kill production. ~0.5" reduces output >80%.

I usually brush off my panels since my array is only 10 degrees. At such a shallow angle the snow never slides off. Fortunately it only snows here maybe 2 or 3 times a year.

 

[dhrivnak]

This is something I've been keenly interested in. How well do solar panels cope with snow. I've read that the snow quickly melts and slides off panels, even in cold conditions. Don't know how true that is.

Mostly true.

 

[MitchMitch]

Not very sophisticated, but if it looks like the snow might be sticking around for more than a day, I spend about 20 minutes with one of these.
I use a squeegee once or twice in the summer too. Probably more work than it's worth, but it's the principle.


Roof Rake

 

[SageBrush]

My panels are on a ground mount so I use a broom