New roof; solar PV as well?

Hi all, I’d like any advice you can give. We are replacing our roof covering, the current tiles have done a decent job since the 30s and are still watertight but they are hanging on by a thread.

It seems sensible to think about solar PV at the same time but I’m struggling to find info about doing both together. Obviously the roof is a decent expense in itself, solar will be too. Normally I’d try to spread the costs a bit over a few years rather than do it all at once, but it seems like there should be some savings by doing both together. Only problem is I haven’t found any clear examples or companies that offer both.

Also does anyone have any recommendations regarding on roof/ in roof / solar tiles in this circumstance?

Doing solar PV and the roof at same time is definitely going to be cheaper just cause you can share scaffolding etc. Solar PV as the roof is probably much more expensive.

Those tesla solar tiles (or similar) have lower yields per m^2 and therefore cost far more than a mass produced standard module per kW (usually the increased area and efficiency doesnt even compensate for losses due to tiling using standard modules due). I think I even read somewhere they have efficiency of ~5%? This is compared to 18 - 20 % for a standard module. So you would need 4 times the area covered than using standard panels. Losses due to tiling wont exceed 20% so standard are generally much better. They only make sense in some parts of US I think with big single storey houses with massive roofs. In Europe with limited roof areas they are a waste of money.

For other integrated mounting systems , some require bespoke modules which , like solar tiles, is probably going to be quite pricey per kW. There are some systems which use trays which are compatible with wide range of standard modules. If you want the integrated ‘look’ thats probably the best compromise as these wont be much more expensive than racks (but you might be charged more for fitting).

Otherwise i would just procure the two separately and do at same time. Obviously can cross-check with both contractors to make sure they arent doing something which makes the others life harder etc.

My main advice: cram as many standard modules onto your roof as you can. You are not actually restricted to 3.6kW in terms of module output, that is the limit for the inverter output on single phase connection. The marginal cost of fitting more panels is tiny compared to all the other costs now. Inverters are now designed to be undersized wrt PV output for this reason. For example, the new sunny boy 3.6kW can take up to 5.5kW in terms of peak panel capacity. It just clips panel output if it exceeds 3.6kW, but it means you get more output over day and either side of summer peak. This will boost your yield for little extra cost. There is a lack of awareness of this even amongst installers.


And we dont official have any recommendations but i did see a video of Oval Renewables doing a semi-integrated install on our youtube today…

So you might want to give them a call!

I have seen a few types of solar tile. Here’s one I looked up just now. Roof Integrated SolarTile® | Marley
And another I saw a few months ago

You would need to take references as IMHO this kind of product is not very mature yet.

Thanks Ben and Paul that’s really helpful

I just had to say Ben , it is great to read your Solar PV advice here - so much clarity in one post. I’m glad I’m hanging back with solar and my roof. You just answered so many of my questions right here.
Once I have my head around heat pumps and this Green Grant - I am jumping onboard with you.

I did make an enquiry for our school with GMCR today - for solar . I’m keeping my ear to the ground for them in all things energy and our options. So I might end up learning about solar more quickly than I’m anticipating if I get involved with schools energy projects.

Hi Ben - very useful as I’m wanting to get a roof replaced and would like integrated solar panels put in at the same time

I’m interested that this integrated panel approach doesn’t use plastic ‘trays’ to mount the panels into like, say, a GSE system. Is the roofing below the horizontal timber mounting ‘runners’ watertight?

Also, any more recommendations or experience of good roofers and/or PV installers would be great :slight_smile:

The roof should be to the spec that you specify to the roofer, which in turn will be obtained from the panel supplier/fitter.
I had an integrated array fitted in 2005 and the fitter was very specific about the under panel construction. In particular they wanted sarking boards, which are unheard of in my part of the country.

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Thanks Tim.

Finally, anyone have any recommendations for good companies? :slight_smile:

Most companies doing the job are regional. Please give your approximate location and others in the same area can make suggestions/recommendations.

Thank you - I’m in withington, south Manchester

As I’m in North London I will need to bow out and let others make their recommendations.

How are you getting on with your roof / solar project Peter?
I’m in Northenden and in the process of getting roofing quotes . I was going to get solar through the Green Grant , but have had so much trouble with them - I’m currently thinking not to bother and procure some integrated solar while we sort the roof.

If you have integrated panels there will be much less ventilation under them and therefore they will get hotter. These days there are panels that tolerate this better than in the past and continue to generate near peak. Be sure to check that your installer specifies such panels.

My integrated panels, from 2005, predate such technology.