Series string shading summed up in 4 pictures

[Will Prowse]

Each row is a string. These two strings of panels are in parallel and connected to victron MPPT. You can see that the last panel is shaded:




420VDC. So plenty of voltage and the last panel in the string is shaded, but only producing 200W for both strings!

Now wait 30 minutes..

The shading is now gone, and we have power!


2465 Watts! The moment the shading was eliminated, the power jumped 10X!

You would think that the bypass diode would do a better job on either string, but it doesn't.

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.

 

[Steve_S]

You should try that with Shingled Cell Panels like the Hyundai ones (hard to get in USA), similar to those that Andy of Andy's Garage got.

 

[SeaGal]

Hey @Will Prowse... I would have expected you, of all people, to find a better place to site your panels

 

[Rednecktek]

Hey @Will Prowse... I would have expected you, of all people, to find a better place to site your panels

Well, with all that overcast cloudy weather in Nevada, he can only do so much. ?

 

[rhino]

You could however arrange those strings such that the bottom half of one of the strings is shaded and you'd get much better results even under shading conditions due to that modules design (forget the term, split cell?)

 

[SeaGal]

Seriously though, that's good to demonstrate a real-life situation, thanks . I feel a discussion about optimisers and/or micro-inverters will follow!

 

[The Good Package]

Are those 200w panels w/ a total of 4000w? Looks like 9BB / half cell so those are supposed to handle shading really well. I find it hard to believe that it was only generating 200w with that little shading, but I am hardly an expert. I assume you weren't "floating" or at 100% SOC during that period so this one leaves me scratching my head...

 

[Will Prowse]

Hey @Will Prowse... I would have expected you, of all people, to find a better place to site your panels

It's worse in the afternoon actually. This array pulls a substantial amount of power. Most useful irradiance for PV occurs when sun is high above. So I'm not losing much over the course of a day.

I have covered this multiple times in past videos and my numbers if you want to know more.

 

[Lt.Dan]

The only way around this is with optimizers, which is just more and more cost. In some cases though, if you have to have RSD (obviously this is with grid-tie systems), then the Optimizer+RSD is not much extra, and will yield more PV over time if there is any shading.

I know some people dont believe in optimizers, but this is just my personal experience.

 

[PreppenWolf]

I would love to see more posts here and videos on your channel demonstrating the effects of shade and different setups. Even if you used cardboard or something to obstruct different portions of panel(s). Very educational for the rest of us.

 

[Will Prowse]

Seriously thought, that's good to demonstrate a real-life situation, thanks . I feel a discussion about optimisers and/or micro-inverters will follow!

Optimizers and micro inverters do not have this issue. Different type of system entirely.

 

[Will Prowse]

I would love to see more posts here and videos on your channel demonstrating the effects of shade and different setups. Even if you used cardboard or something to obstruct different portions of panel(s). Very educational for the rest of us.

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

 

[Will Prowse]

The only way around this is with optimizers, which is just more and more cost. In some cases though, if you have to have RSD (obviously this is with grid-tie systems), then the Optimizer+RSD is not much extra, and will yield more PV over time if there is any shading.

I know some people dont believe in optimizers, but this is just my personal experience.

Exactly!

 

[The Good Package]

The only way around this is with optimizers, which is just more and more cost. In some cases though, if you have to have RSD (obviously this is with grid-tie systems), then the Optimizer+RSD is not much extra, and will yield more PV over time if there is any shading.

I know some people dont believe in optimizers, but this is just my personal experience.

Or more panels...

 

[Lt.Dan]

Or more panels...

If you already have shaded panels, adding more panels just equates out to more shaded panels and no gains.

 

[The Good Package]

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

Sounds like you have enough 2.0 content lined up for a while. Not a bad problem to have as a creator...

 

[Rednecktek]

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

And yet I send those videos to newbies all the time. Great resources even if some of them are a little outdated now. I've even been known to rewatch quite a few of them from time to time.

And yes, I still recommend the book and have no regrets about buying my 2 copies right before the price drop. ?

 

[Will Prowse]

Are those 200w panels w/ a total of 4000w? Looks like 9BB / half cell so those are supposed to handle shading really well. I find it hard to believe that it was only generating 200w with that little shading, but I am hardly an expert. I assume you weren't "floating" or at 100% SOC during that period so this one leaves me scratching my head...

Here are the panels used:



Yes I always figured that bipass diodes would do a better job, but time and time again, parallel configuration has been better on a few of my systems. I find it odd that voltage can be that high and the current is just awful. The bypass diode never seems to work in my systems.

 

[Will Prowse]

Sounds like you have enough 2.0 content lined up for a while. Not a bad problem to have as a creator...

What do you mean by 2.0?

 

[Will Prowse]

And yet I send those videos to newbies all the time. Great resources even if some of them are a little outdated now. I've even been known to rewatch quite a few of them from time to time.

And yes, I still recommend the book and have no regrets about buying my 2 copies right before the price drop. ?

Thank you