Series string shading summed up in 4 pictures

[OffgridMatty]

What is the system voltage, what VOC are you operating at, and what kind of panels are you using?

Each panel has a Voc of 48.1. They are 375w panels and I was running three of them in series. My AIO had a max rating of 145V so once my panels got in cooler weather and got more efficient, I was going to be in trouble. They now show about 38-40v in the string and Amps depends on the amount of sun. It has an Imp of 9.36A

 

[sunshine_eggo]

This was discussed in another thread about shading. In my tests over the years, the bypass diode really doesn't help that much. Usually my output drops significantly if any of the panels are shaded. This is why parallel connection does significantly better when you have shading issues.

I hear you bro. Message received.

I am NOT inclined to blame the SCC in this case.

 

[Rednecktek]

I hear you bro. Message received.

I am NOT inclined to blame the SCC in this case.

I blame his refusal to tear down the wall. ?

 

[cs1234]

If there is any shade on your panels, at any time of the day, you are probably better off paralleling them. Though I didn't log the data, I found that I lost more power overall through the day from partial shading in series than I did by increased amperage causing voltage loss with paralleled panels.

The nice thing about panels in series however, is the voltage limit on some of the controllers go up pretty high. 40v panels at 10 amps overrun 8-10 AWG cable limitations much faster in parallel than charge controller limitations on some of these AIO's in series. You have to be willing to run a ton of separate cables to do significant panels in parallel.

 

[cs1234]

I blame his refusal to tear down the wall. ?

He just needs to raise the panels higher until they aren't in the shade. ?

 

[rhino]

This issue is only present for about an hour and the output during this time is awful. I would have to chop down a wall and livestock shade. Absolutely not worth it at all. I just add more panels and capture more when the sun is overhead. I do not want to tear down my backyard for low angled sun. Not worth it at all.

I wasn't clear. Just rotate the arrangement you have now 90 degrees.. So one string would have the the bottom half shaded and one string in full sun. In that scenario I think you'd get close to 75% of output of all the panels being in full sun. Saying this since you are trying to make a point about series arrangement but your current arrangement shows worst possible arrangement. With the panels you have I believe you can shade one half of an entire panel (top or bottom) and still get half the panel output instead of none like you do by shading parts of both the bottom and top of a panel.

 

[Will Prowse]

I wasn't clear. Just rotate the arrangement you have now 90 degrees.. So one string would have the the bottom half shaded and one string in full sun. In that scenario I think you'd get close to 75% of output of all the panels being in full sun. Saying this since you are trying to make a point about series arrangement but your current arrangement shows worst possible arrangement. With the panels you have I believe you can shade one half of an entire panel (top or bottom) and still get half the panel output instead of none like you do by shading parts of both the bottom and top of a panel.

Ohh I understand. With these panels it would be difficult because the leads are very short.

 

[Will Prowse]

I wasn't clear. Just rotate the arrangement you have now 90 degrees.. So one string would have the the bottom half shaded and one string in full sun. In that scenario I think you'd get close to 75% of output of all the panels being in full sun. Saying this since you are trying to make a point about series arrangement but your current arrangement shows worst possible arrangement. With the panels you have I believe you can shade one half of an entire panel (top or bottom) and still get half the panel output instead of none like you do by shading parts of both the bottom and top of a panel.

And it's only bad for thirty minutes or so. And the output when the sun is that low when it's shaded is not worth the effort at all. I'll just add more panels. I mainly care about collecting photons when sun is overhead than when the sun is low.

 

[timselectric]

I've covered this before actually. People don't watch my older videos sadly. People keep requesting me make videos I've already made and it's driving me bananas lol

When can we expect this video about bananas driving?
Or maybe I miss read. lol

 

[Rednecktek]

When can we expect this video about bananas driving?
Or maybe I miss read. lol

And how to wire those bananas into a Chiquita BMS. ?

 

[defelker]

It would be interesting to install one Tigo optimiser on each shaded panel and see if the power is better when shaded.

 

[cs1234]

It would be interesting to install one Tigo optimiser on each shaded panel and see if the power is better when shaded.

It would be interesting.

 

[Lt.Dan]

I mean I can just post the data from my Tigo App showing the crazy difference the optimizers see and save. I have 1 panel that gets shaded by an eve of my porch. The 1 panel shows under performing until about 1pm, but the other 10 in the string (11s2p setup) are not restricted at all.

 

[The Good Package]

It would be good to see series / parallel testing with brand new modern panels that specifically advertise their bypass diode and hot spot mitigation features. Bypass diodes can get fried easily (especially on cheap panels) and it's one (of many) reasons why I avoid used panels.

This is also an atypical "hard shading" scenario being so close to the wall and on the ground, which works the diodes hard. Typical shading would be from trees or further away objects and light diffusion would mitigate some of the shading's effect. Only pulling 200w with that limited shading leads me to believe you have problems with your (2019?) panels and you should test the diodes. It would make a good video as I think everyone would appreciate more in depth technical topics like panel circuitry testing and diagnosis.

I'm not saying series is better than parallel, but there are a number of variables that can skew the results.

 

[cs1234]

I mean I can just post the data from my Tigo App showing the crazy difference the optimizers see and save. I have 1 panel that gets shaded by an eve of my porch. The 1 panel shows under performing until about 1pm, but the other 10 in the string (11s2p setup) are not restricted at all.

You could, but Will making a video out of it would be cooler.

 

[Lt.Dan]

Just for fun, here you can see D11 at 12:45pm and 2:15pm. Theres a SHARP ramp up in power from 1:45pm to 2:00pm though. Exactly when the last cell is unshaded. You can also see total recovered at the top right, 7.1kWh extra that I wouldn't have gotten without the Tigo Optimizers.

For more info, the bottom array is South/South East, the top left is South/South West, and the top right is North/North East. Each Group (A, B, C, and D) are in series, and A+B are in parallel, and C+D are in parallel. You can see even with the very mixed orientations of the panels in series (Group C in particular) the output is still very good.

 

[The Good Package]

Just for fun, here you can see D11 at 12:45pm and 2:15pm. Theres a SHARP ramp up in power from 1:45pm to 2:00pm though. Exactly when the last cell is unshaded. You can also see total recovered at the top right, 7.1kWh extra that I wouldn't have gotten without the Tigo Optimizers.

For more info, the bottom array is South/South East, the top left is South/South West, and the top right is North/North East. Each Group (A, B, C, and D) are in series, and A+B are in parallel, and C+D are in parallel. You can see even with the very mixed orientations of the panels in series (Group C in particular) the output is still very good.

You have a Tigo on each panel?

 

[Lt.Dan]

You have a Tigo on each panel?

Yes, all of them. This is grid tie, and here in California, all panels must have Rapid Shutdown Device, so the optimizer serves both purposes.

 

[cs1234]

Looks nice. What's the bare minimum Tigo equipment you need to get the neat monitoring software going?

 

[The Good Package]

Yes, all of them. This is grid tie, and here in California, all panels must have Rapid Shutdown Device, so the optimizer serves both purposes.

If my math is correct, the 7kwh gained with the Tigos roughtly cost around $0.35-40/watt? Cheaper than adding more panels, right?