Estimating shading?

xclacksoverhead

Hello, I recently moved to a new property and have been considering getting solar + battery installed before the 0% VAT rate expires. I've sought some quotes from national and local companies and right now I have a £12.7k quote for a 7.1kW system on 3 strings with a Tesla PW3, bird proofing, G99 etc. On the quote, they are estimating a ROI of 13 years.

My biggest issue is that my roof gets some degree of shading from a row of trees about 13-15m to the south of my property. I asked the installers for their opinions on whether it would materially affect the solar generation, but they were all confident it would not be a roadblock to getting a return from the system, or they alternatively offered a system with optimizers.

I'm looking for some independent advice as to whether or not this is too much shading? It was pretty minimal shading in early September. Any thoughts or advice would be much appreciated, as I feel a little lost on this one.

Newbie_John

Im sure you'll get a better quote here..

But I wouldnt worry much about shading in calculations, sure there is some, not ideal but it will still generate a decent amount.

Bigger worry with ROI is not knowing export rates in 2028 and beyond.. if they drop to 0p/kWh during midday then the shaddow isnt a problem at all :)

You have decent all around roof - and thats a really good thing - export prices in morning and evening should remain high + battery.

Just get a better quote and check your mortgage provider for any type of green grants they may have..

QrizB

Assuming those photos were taken recently, I don't think the shading is going to be a major issue. During the peak generating season of April to September the shading will be less or nil, while there's not much generation to lose in December or January.

On the quote, £12.7k for 14(?) panels in three strings and a PW3 is in the right sort of ballpark. You might be able to shave a little (paging @Screwdriva ) and/or get higher output by choosing slightly more powerful panels (Eurener 515W seem a popular choice at present) but it's not extortionate.

michaels

There is that old schoolboy thing about measuring the height of something by going a known distance from the base and measuring the angle. You could then google for the azimuth angle by date and figure out how much shading you might get. In fact you could probably put the heights, distances, roof pitch and orientation into google and ask it how much impact the shading might have. With 3 strings you installer should to some extent be able to make sure that panels shaded at the same time are all on the same string or alternatively go for optimisers if not much more. We are very lucky to have optimisers as our neighbour has extended their loft meaning some of our panels are now very shaded.

Screwdriva

I agree with the comments above - the shading is not significant and should easily be mitigated by good string design and each panel's 3 bypass diodes.

Installers I use to help others offer 14 X Eurener 515W Bifacial panels (7.2+ KWp) paired to a Tesla PW3 with Gateway 2 for ~£11.7K installed, including bird netting, G99 application and 10 year workmanship warranty.

Based on this, I'd say you can do better. I'd also suggest getting the trees sympathetically trimmed if TPOs aren't a factor.

Martyn1981

Agree with all. Shading doesn't look horrendous. It would be nice to have a tad less in September, but not the end of the world. Good combination of roofs, and the PW3 taking 3 seperate feeds. Good generation, certainly Mch to Sept.

xclacksoverhead

Thank you all for the advice, much appreciated and great to hear the advice broadly matches the installers.

Yes, pictures were recently taken and the shading was better in early September. Tree trimming isn't an option here unfortunately.

I'm with first direct who don't appear to have anything on offer in regards to green initiatives. And yeah it's 14x 510w Aiko panels.

Thanks for the advice re the quote @screwdriva. This was the best of 7 quotes, I will DM you if that's alright, to find out more about the installers you mentioned.