I have to two panels from Eco-Worthy and they drop so much with a just a little shade. Bought them before Renogy came out with the anti shading panels.

 

I would say this is more than slight, looks like at least 8 cells 50% shaded.

 

There are 72 small rectangles - not sure how they are connected together to form a cell. Is it 72 cells? Or if they run L to R then 18 cells? Or top to bottom than 4 cells? There's 11 small rectangles affected by the shade. So not 11/72 = 15% effected?

I was hoping that something like this would drop potential output maybe 30% at most?

 

Since they're already in parallel... pull plugs and see what the difference between the panels is? I've always been curious about the real-world on this...

 

What power outputs are you seeing? If the sun is at 45 degrees (just a guess looking at the shadow) then output from a horizontal panel is already going to be down 30% just from not pointing directly at the sun. Partial shading could bring it down another 30% to 50% or more depending on the panel design.

You can guess at the connection between the cells of the panel from the number of cells and the Voc of the panel... looking at the panels I have:

- 100W with 33 cells and Voc of 22.3V -> 0.675V per cell
- 100W with 36 cells and Voc of 24.3V -> 0.675V per cell
- 200W with 72 cells and Voc of 45.4V -> 0.630V per cell

For the two 100W panels the connections between the cells are visible under the glass and everything is in series. For the 200W panel you can't see the connections but based on voltage per cell I'd guess all the cells are in series for that panel too.

 

I recently posted about my solar production drop with a relatively small amount of shade. Im measuring over 40% production loss with just over 1% shade on the panels.

 

The specs from Rich Solar on the 24V 200 watt panel say "18 busbar solar cell configuration" so in theory, a little shade shouldn't reduce the panel output to 0 like one big series circuit cheap panel. From the photo, I count 18 rows so those must align one per busbar. 11 have a bit of shade on them so maybe worst case a 61% loss of the potential panel output vs. the same panel near it that is in full sun.

Now that gives me something to work with. I'll mess around with plugs and see if things match that expectation or if the real world has something else going on. Doing so means unbolting so that's always a PITA ladder dance.

Not trying to figure out current output vs. the 'perfect' 200w rating (tons of variables with our location, panel angle, weather, cloud cover, etc.). Just trying to compare one vs. the other identical panel and see if I've got some other warranty issue going on (some spidery looking cracks in the black parts all over one of them; haven't checked the other closely yet).

 

Your panel looks like a 9 BB, not the newer 18BB listed on the Rich Solar Site. You can see the individual lines in each cell. The good news your shading only covers 5 of the 9 bus bars. This means that the total cell is not blocked and still passing some voltage and current. I would suspect that you have 4 rows of 18 cells, with probably 4 bypass diodes. The other good news is the shaded cells are most likely in the same row. It would be worse if the shaded area covered multiple rows.

 

As @Scalf77 mentions it's all about the bypass diodes. See if you can find tech specs that explains how many your panels have and how they are wired up. You might have to contact the customer support for your panel manufacturer, I did with Zamp, they didn't publish the information but they were happy to provide it when I asked.

I agree with @Scalf77 that a good guess is that each of the 4 main columns has its own bypass diode. If that is the case and assuming that the shading is enough to make the bypass diode kick in, you'd expect that whole column to be taken out of the power producing circuit and I think that means the panel would be expected to produce roughly 3/4 the power it would if it was unshaded.

If your 2 panels were in series then the 2nd would be limited to 3/4 power as well but since they are in parallel the 2nd panel has the capacity to put out full power. However the two panels are no longer identical so they are going to have different P-V curves and if they are hooked up to the same MPPT controller it likely won't be able to maximize the power output. Using 2 separate smaller MPPT controllers (1 for each panel) would allow the power output to be optimized in this situation but that could be a very marginal gain.