Solar Panel Shade Test - How much power loss? Crazy results

So do you know how solar shading will affect you power generation? I will test out my growatt string inverters for power loss caused by shading single to multiple panels partially to see the results. My solarever panels on in series on each inverter. The results are interesting!

Equipment for DIY Solar Generator

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[ridemfast]

A quality inverter such as SMA or Fronius has better MPTT algorithms that addresses shading issues much better than other brand inverters. But, they do cost more. Also, partial filtered shading such as tree branches would provide different results. None the less, thank you for sharing!

[s]

I wonder if you gave your inverter enough time to 'counter' the shade with it's algorithms. Growatt documentation would surely tell you...

[callmebigpapa]

Could you do a more realistic shading where something like say a tarp is block direct sunlight but is say 10 feet away so the panel still gets indirect light?

[shawnroddick]

There are bypass diodes built in so it will bypass the string of cells in that series. I believe there are three strings each panel so three bypass points ...having one or two still producing will drag down the whole systems amps in series or the volts in parallel. I have been doing a lot of video watching on these issues 😅 😂😂

[kevinc]

Cardboard covering them is not shade, it's more like total darkness.

[mrgruisinge]

Interesting. My solar charge controllers have a feature called 'partial shade detection'. It comes set to on as a default and I left it there. I can't get to my array as it is on a roof 16' up and I really don't get much shading, maybe a tree branch during the shortest days of winter. Snow is different however. With almost all of my panels having some snow on them output was down a fair amount, but, not more than about 50%. I will have to see what Victron says about the partial shading setting. Good food for thought. Thanks.

[Do_the_Dishes]

I would be curious to know as to how hot those covered cells were getting. Some of that power loss was being dropped across the shaded cells.

What happens is that by covering some cells, in a string of cells, you will cause a reverse bias condition on the shaded cells. This means that the shaded cell is acting more like a resistor and dropping the voltage across it, causing a “hot spot” on the shaded cell or cells. Not good by the way. If each and every cell had a bypass diode on them (which they do not) then the power would go around that individual shaded cell instead of being forced to go through it. When the power is forced to go through a shaded cell, the shaded cell becomes more like a resistor, dropping the voltage across it and heating it up (basically trying to produce light). Typically, solar panels only have bypass diodes installed for strings of cells instead for each cell. This limits the shading problem to that string only.

So imagine if your whole array had “no” bypass diodes. And one bright sunny day a big bird decided to shit and cover one single cell. That single cell would be subject to the potential power of the whole system. By having bypass diodes in strings, the whole system will go around that particular string with the bird shit on it. However, that one cell covered in bird shit is still subject to the rest of the cells in that same string dropping their load on it. Pun intended.

[Reman]

I'm now kind of curious how drastically the output would drop of if ALL of the panels were getting hazy scattered light (Like you'd get through a bare trees shadow in winter)? Would the system pretty much say "Nope. Not a chance" because too much of the string was partially affected, or would a few KW's still squeeze through? I'm guessing it would probably be similar to the output with heavy cloud or fog?

You wouldn't happen to have a bloody great roll of fine mesh netting just kicking about around there (and a spare afternoon) by any chance? 😁