Every other panel on the array is clear of snow, rest are covered - is my theory correct?

[Hogheavenfarm]

My 185w panels are set up as 2S3P, I noticed after the last snow a week ago that every other panel had snow on it, which I thought was odd but didnt think any more about it. This morning I noticed it again after another light snow.
Walking out and checking the clear panel, I noted it was the "fed" panel in the series, the one that the positive lead went to the combiner box, this was true of all the panels I noted that were clear.
I am assuming that this second panel is getting the 44 volts from the first panel and adding its 44 volts, and somehow that is melting first panel off quicker than the first panel in the series. Is this correct? or is there something else at play here.

 

[farmhand]

?

 

[caki]

No, your theory is not correct. The way I think of electricity to make it simpler is to think it is plumbing and solar panels/cells are water pumps. If a pump is working is adding water and pressure to the line (voltage). If it is not working it is a source of friction that reduces voltage (that generates heat). So, if you would measure the voltage across both panels it should be 44*2. If you measure between each panel it will be 44 because you are measuring the difference between the two points. To my plumbing analogy when you measure the water pressure you always measure against the atmospheric pressure, i.e. common ground.
Back to your problem it would be interesting to rewire the panels so they are in reversed position on the 2S3P and see if the melting then happens on the second panel. Your issue seems that some panels are producing a little bit more heat what is visible under light snow. Are they identical? Same age?

 

[farmhand]

No, your theory is not correct. The way I think of electricity to make it simpler is to think it is plumbing and solar panels/cells are water pumps. If a pump is working is adding water and pressure to the line (voltage). If it is not working it is a source of friction that reduces voltage (that generates heat). So, if you would measure the voltage across both panels it should be 44*2. If you measure between each panel it will be 44 because you are measuring the difference between the two points. To my plumbing analogy when you measure the water pressure you always measure against the atmospheric pressure, i.e. common ground.
Back to your problem it would be interesting to rewire the panels so they are in reversed position on the 2S3P and see if the melting then happens on the second panel. Your issue seems that some panels are producing a little bit more heat what is visible under light snow. Are they identical? Same age?

I'm curious as fluff snow fell here and my panels 12poly/12mono 3S6P are all the same. When I went to sweep off snow it all felt the same. I have reversing diodes on each string in the combiner box.... so maybe that's it.

-But if heat is wasted energy.... is Hog Heaven wasting power during regular days?

 

[50ShadesOfDirt]

No automatic clearing of snow from any of my panels by internal heating ... manual labor only ... don't know if that's good or bad.

 

[Hogheavenfarm]

All the panels are identical, at least 15 years old. Only happens on the six 185w panels, not on the 4 hundred watt panels (also in series).
Switching them sounds like an interesting test, if I can get to that I will try it.If it was a bad panel I doubt they would all be on the same side of the series connection. My panels are pretty old though, they may not have all the diodes the newer ones have. (They may be older, Schuco stopped making panels 15 years ago, I am going by that info.) Grabbing a pic next time too, we have more snow in the forecast.

 

[Hogheavenfarm]

Okay, this last storm made it difficult to see the same results I have been seeing as the snow was very heavy and wet, falling quite rapidly, and very high winds with it, freezing almost on contact, so lots of resistance to melting. The other snows were light and fluffy with no wind, and that seems to show the issue much more clearly, however here is a pic for <future> reference - In the past, all the melted panels looked like panel 3, that would be panels 1,3,5 and 7. All of those panels are on the positive side of the series. All unmelted panels looked like panel 4. There is some evidence of the issue on this pic (3 and 1), but not much this time. Minor load was on at the time , maybe 120 watts, no solar input obviously.

 

[12VoltInstalls]

My panels are vertical.
They collect no snow.

I’d be more suspicious that you are feeding back battery voltage?

 

[Hogheavenfarm]

check with a meter at the combiner box? Actually I have an LED voltmeter installed in there, just have to see if there is voltage present (often I see 2 volts at night, I assume thats from the spotlights kicking on from the motion detector, but maybe not. )

 

[50ShadesOfDirt]

It may be that the affected solar panels actually have some sort of damage (electrically) that you can't see by casual visual inspection; perhaps this subtle damage is "heating the panel". The lack of snow is then a visual clue ... I note that none of my panels clear off faster than any other, although once the sun breaks through snow layer to dark surface, then melting speeds up.

I'd hit them with an IR temp gun (or camera, etc.), and see if it looks any different than neighboring panels.

This site had some interesting ways that solar panels fail:

http:// winaico.com/blog/common-solar-panel-defects/

 

[Hogheavenfarm]

These are old used panels, so anything is possible. There are some with snail trails, and I thought I saw a few hot spots, although not burned areas, just slightly discolored circles, nothing else looks too bad. IR gun may be a possibility. Will have to look into that.