Should shading make this much difference?

ely_ellis

Now I am home, I'm being picky with my system.

I have a small bit of shading in the morning but I am surprised what a drastic difference it is making on the power of that panel.

I have taken a couple of photographs to show what I mean.

The first photograph was taken at 08:50 and shows the bottom right corner of the panel shaded; I would estimate 10% shading of the panel.
The output of this panel is almost nothing, just 12w while all the other panels are up at about 110w.
This output remains around the 12w until at 09:15 when the power suddenly shot up to 102w with just the tiniest bit of the bottom corner shaded, about 2%.
In conclusion, that means the panel will output virtually nothing with just 3% shading!
Or do I have a problem?
I have SE optimisers, so could it be the optimiser that is causing this. I knew shading would make a difference but surely not such a drastic difference like that.


08:50


09:15


Graph showing the sudden surge in current


Cheers

pinnks

Martin,

The answer is probably yes - have a read of this thread https://forums.moneysavingexpert.com/discussion/5188307

tunnel

Totally normal(unfortunately). Think yourself lucky you have solaredge as without it your whole system could have been taken down by that one panel.

theboylard

As Tunnel says, if you had a normal string inverter installation, then that little bit of shading would have dragged down the whole string as a string operates at the lowest common level, thus kneecapping your generation across potentially half your array.

This is what I had with mine, without SolarEdge!!

The figures since fitting SolarEdge prove this - I posted a pic the other day and by averaging the panels performance out by the shading affected panels (2 closest the chimney), then taking the lowest figure of all the panels not affected by shading, so being very conservative, I am half a MegaWatt better off than I would have been!

So purely on financial terms, if FiT rates stay the same for the next 19 years (which they won't obviously!), then fag packet maths says that I will be better off by £3365 at the end of the FiT term.

Blimey!

Any maths wizards want to check my figures?!!

I'd not done any real thinking about this previously, but this could be a costly mistake for the installer if I chose to pursue it?

So in short MartIn, be happy you had some good guidance from the regulars on here, I only got involved here after my install - although I've just discovered that I can't see my posts before March this year so can't confirm that!

ely_ellis

Thanks guys.

I knew the effects of shading were bad and it would affect the whole string, but just did not realise HOW bad and how minute the shade would need to be to cause this much drop in output.

I do not think ANY of the companies I had quotes from said I would get shading issues and on several of the companies I brought the subject up and was told I would NOT get any shading.

The final installation was NOT one of any of the company’s offerings and were more of my own design / suggestion including the fitting of SE from the knowledge I have gained from everyone on here giving me enough information to dig deeper.

To be honest, one of the main reasons for the SE system was not for shading issues but for monitoring, (I like numbers and graphs), so looks like the correct decision was made.

Thanks everyone.