# Forum Home Renovation Solar Electrical Systems  Is this panel shading is acceptable for new install?

## Llessur

We've recently had 13kW of panels installed on the roof of our new extension and it looks like several of the panels will receive partial shading from two protruding skylights for some of the day. I've attached a photo below showing the problem at 6pm a few days ago - it appears the shading will start at around 4pm and track round in an arc until around 7pm to about the same extent as shown in the pic. We're not using micro inverters or optimisers. 
However, I'm aware that in winter the shading will be bigger and last for longer - some rough calculations from an online calculator shows it will start around midday and extend through to sunset. It will probably also cover around twice the area of the panel that is is currently does now in summer. For some portion of time the shadow will overlap the join between two panels.   
I've read up quite a lot around the effects of partial shading and I'm not particularly happy with this outcome, especially as I feel there was plenty of available roofspace to install panels further to the east, further away from the skylights. I did also send through photos of the skylights a few weeks prior to the install asking if they would present any shading problems but didn't get a reply so assumed all was good. 
My question is how much is it appropriate to push back on the installer around this? I always try to be really fair to tradies in terms of my expectations vs realistic outcomes so I just wanted to get some opinions on whether I'm right to push hard for a resolution to this? Or, in the age of bypass diodes and MPPT is some small level of shading generally acceptable for an install and to be expected? 
Moving the affected panels out of this shade will probably require a couple of new rails, or extensions added to the existing ones - and one panel might need to be moved completely to join the end of another row of panels. I don't know what impact to wiring there will be but assume there will be some. 
The installer is going to come and take a look next week but from conversations I get the impression that they don't think the level of shading is a major problem. I haven't paid the invoice yet as the install is not yet finalised at the switchboard end, so I probably still have some leverage.

----------


## Uncle Bob

What's your app telling you when the shade is hitting them? Can you notice it?  To me it actually looks real tidy and if they move it mightn't look quite as nice.

----------


## Llessur

The system isn't commissioned yet - I'm still waiting for the switchboard side of things to be completed.  
It is otherwise a really good install and I have no problems at all with how it's been done but at the end of the day it's on a roof which no one will see so I'd value maximising output over neatness. 
Also there might not be much of a problem in the middle of summer but I don't really want to find that in six months' time I am seeing a significant drop in output with the more extensive winter shading - it would presumably be much easier for me to get any issues sorted out now rather than trying to chase them up half a year after they've installed it. 
Maybe one solution would be to get in writing from the installer that we'll monitor output over the course of a year and address the problem should it have a significant effect on output. 
However, in addition to output isn't shading also a problem re: the longevity of panels - hotspots, failed bypass diodes etc?

----------


## havabeer

can't you just put a mirco inveter/optimiser things of the couple of affected panels?

----------


## Bart1080

Need more info. 
So how is it designed?  Is it designed with micro invertors or optimisers?
What's the invertor that was installed?
Is the shading only on 1 string or circuit of invertors?...A system that size is likely to have 3 or 4 strings (groups of panels wired together) and then all joined into the invertor. 
Regardless with the above questions, your likely not going to find a big enough issue to worry about even if you don't have micro's or optimisers.
Why, so you have issues with 2 hours at the end of the day when the output of the panels are likely to be less anyway with the sun angle etc. 
If your really concerned, why not just drop your skylight to the same angle and height of the panels...problem solved if you simply have a standard string invertor system. 
Easy way to see if there is any significant drop in output is through your app (assuming it comes with one) to see the drop once the shade hits the panel.
Be prepared to see a drop in the middle of the day when your panels get too hot in the summer.  
There are plenty of installs that have partial shading during different periods of the day and in some cases its just simply that the customer has to realise if that is where they want the panels or roof space is limited or with different roof space angles (east, west etc), then they have to either live with a reduced output from the entire string or ensure its designed with technology that provides the best result to handle the shaded panels such as micro-invertors or optimisers but that does come at a cost...and sometimes significant.
Its an older article but a good start on an "opinion" which like most is subjective  :Smilie:  https://www.solarquotes.com.au/blog/...ption-is-best/ 
I've a same size system put in 12 months ago and went to an Enphase microinvertor system, ~2k more expensive but my reason was to see how each panel/micro invertor was performing and any issues with a panel or microinvertor would be easily visible over the longer term.  I dont have a shade issue except for when the sun is really low in the west late in the evening....however statistically most installs are string invertors probably due to the extra cost.....and looking at yours, if the shading was known it might be a difficult cost proposition to spend the additional ~2k based on the small losses.

----------


## r3nov8or

I have two strings, 14 panels each, and this is what the neighbours tv antennae does to one of them in May, June, July during the early arvo.   
As others have said, it depends on your system's design and the time of day that the shadow is happening, as to whether it would be a concern and worth addressing

----------


## Pulse

A 13kw system should have plenty of spare output, it is not ideal but some shading especially that late seems acceptable. I have a 9kw microinverter system and shading was one of the reasons.

----------


## John2b

What's the point of the raised skylight?

----------


## Llessur

Cheers for the replies all. Just to answer a few questions: 
We're using a Goodwe GW10000 inverter, not micro inverters or optimisers. There will be three strings - two on a north-facing but shallow pitched roof (this is where the skylights are) and one on the western pitch of the existing house roof (no skylights). The skylights on the shallow-pitched roof are on 400mm high flashings as there was a minimum pitch required for the size and style of Velux window we needed for the area. They can't be changed. 
The two skylights will each impact one of the three strings equally - so two of three strings will be impacted and at exactly the same time of day as the roof and panel layout is symmetrical. 
I think my problem is that I communicated the presence of the skylights and enquired about shading issues to the installer several weeks before the install so I assumed they would be taken into account re panel placement. There is plenty of unshaded roof space available so in my opinion there was no reason to install any panels which would experience any shading at any time of day. 
I've done some rough shadow analysis online and the shading will be much more significant in winter - panels will be shaded from 10am each day, with the maximum extent of shadowing being almost the entire width of the affected panels.  
I just want to know if I'm in the right for trying to push hard to have these two panels relocated to unshaded parts of the roof?

----------

