Do half-cut panels out-perform on overcast days?

[kolek]

Referring to his half-cut solar panels, Fafrd posted saying "Interestingly, on overcast days I can actually get as much output as I get on clear days."

Here's the post:

Will shading keep me from getting ANY solar power in the winter?

I'm considering a grid-tied system that would also be off grid during our frequent power failures. I would anticipate putting a row of panels in portrait mode just below the peak of my roof (that faces 187°) and another row below them across the upper part of the front-porch roof - about 30...

diysolarforum.com

Anyone else here with half-cut panels?
If yes, is your performance on overcast days almost as much as clear days, or is Fafrd's results out of the ordinary?

 

[rmaddy]

I believe you are referring to this part of the post by @fafrd :

Interestingly, on overcast days I can actually get as much output as I get on clear days. The clouds reduce overall output levels but the diffused light eliminates the shading so I get about as much output as I’d get without any shading (in the presence of overcast / clouding).

This needs to be taken in the context it was posted. This is in a heavily shaded setup. So on a sunny day there is a lot of shading. The half-cut cells do help improve output in such a case. Then they claim that on an overcast day, the diffused light eliminates the shadows. The end result is that their setup gives about the same result in both sunny (but heavily shaded) conditions and in overcast conditions.

This in no way means that if you put half-cell panels out in an unobstructed view of the sky (no shading) that you would get the same results on an overcast day as you would on a clear sunny day.

I have 3 half-cut panels in series, each with two bypass diodes, mounted flat on the roof of my trailer. I would never claim that the panels provide similar results between overcast and sunny when I'm parked out in the open with no shading. But I do believe the half-cut panels really do help in shade. As I type this I'm camped in a heavily treed area. There's virtually no sun hitting the ground where I'm parked yet I'm still getting a tiny bit of power (16W from 990W of panels). The previous two weeks I was in a camping spot with lots of trees but as the day progressed I would get varying swaths of sun hitting some of my panels. I'd get periods of 100W or so. For one hour each day the sun would get in just the right position and I'd get 750W. The rest of the day it would bounce between 15W and 120W as various beams of light would get through the trees. I don't think full-cut panels would give me as much in the shaded conditions.

 

[kolek]

I believe you are referring to this part of the post by @fafrd :


This needs to be taken in the context it was posted. This is in a heavily shaded setup. So on a sunny day there is a lot of shading. The half-cut cells do help improve output in such a case. Then they claim that on an overcast day, the diffused light eliminates the shadows. The end result is that their setup gives about the same result in both sunny (but heavily shaded) conditions and in overcast conditions.

This in no way means that if you put half-cell panels out in an unobstructed view of the sky (no shading) that you would get the same results on an overcast day as you would on a clear sunny day.

I have 3 half-cut panels in series, each with two bypass diodes, mounted flat on the roof of my trailer. I would never claim that the panels provide similar results between overcast and sunny when I'm parked out in the open with no shading. But I do believe the half-cut panels really do help in shade. As I type this I'm camped in a heavily treed area. There's virtually no sun hitting the ground where I'm parked yet I'm still getting a tiny bit of power (16W from 990W of panels). The previous two weeks I was in a camping spot with lots of trees but as the day progressed I would get varying swaths of sun hitting some of my panels. I'd get periods of 100W or so. For one hour each day the sun would get in just the right position and I'd get 750W. The rest of the day it would bounce between 15W and 120W as various beams of light would get through the trees. I don't think full-cut panels would give me as much in the shaded conditions.

Thank you that explanation helped a lot!