Solar with considerable shade

gmc600

Hi,

I'm looking at putting solar on my double garage in Glasgow, according to Easy PV I can get a 4 kWp system to fit and without shade it would generate 3500 kWh per year without a battery. The roof is facing roughly SW (28° from S). Only thing is that there is considerable shading from my house and my neighbour's house, especially when sun is lower in winter. Easy PV lets you add other buildings and gives a 3D model output showing exactly when the panels will be in the shade but for some reason they ignore this when they calculate the total generation (perhaps this is a paid feature). Does anyone know of a free tool than can give me an estimate of how much I can expect to actually generate?

I'd put panels on the house but best location is already taken up by solar thermal panels.

Thanks

Martyn1981

Apologies, as this isn't what you asked (hopefully someone will come along soon), but do you have any other options? Could you build a ground mount further back on the property so shading from the houses (in the summer) is reduced? I think Scotland allows 12m2 (rather than 9m2) permitted development (PD), but you can of course just build a structure like my 'ladder store', chicken coop, log store etc, and put PV on the roof, no PP needed.

How about wall mounted panels if there is space on the front of the house, that too is now PD, but worth checking for local restrictions. Also, how much benefit do you get from the solar thermal especially in the colder 6months? Could you consider shifting that to the garage so it's still viable in the summer (despite shading), and use the front roof for PV?

I suspect none of these options are viable, nor what you were looking for, but just thought it worth mentioning in case.

gmc600

Hi Martyn,

Thanks for your reply, no other options really unless I put them north facing (which these days might actually make sense if I wanted more panels than I could fit on the garage). I didn't know wall mounted was an option, wonder how that would compare with mounting them on north facing roof.

The solar thermal is great in summer so I don't want to dismantle it just yet even though it doesn't do much in the winter, moving it would require a lot of work and long hot water pipes running outdoors. Thanks for your suggestions. I've actually found that OpenSolar can calculate the effect of shading (not sure how accurately but in my case it's saying that I'll lose ~15% of yearly output vs. 40% if I had them north facing).

Screwdriva

If you decide to proceed, I recommend either optimizers or microinverters. I also recommend bifacial panels with a white painted background, as they perform well in cool, overcast conditions and can capture irradiance better than a mono facial can.