Mon, 17 Aug 2026 03:10:57 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277757#Comment_277757 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277757#Comment_277757 Tue, 07 Jan 2020 08:19:01 +0000 aclarky
I live in a conservation area and can't put solar PV on the roof. I want to build a shed to the side of the house and wondered if I should put solar panels on the roof - I know it would be shaded but panels seem pretty cheap now and could save on slating/roofing the shed costs.

I could fit 10 panels on the shed and it looks like they are down to about £100/panel. + inverter £?

Would it be a complete waste of time? I saw something about wiring them in parallel... We would use all the elec they produce and are installing a NIBE GSHP which can preferentially use solar PV when available..

Any advice very much appreciated.

Cheers

Andy]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277759#Comment_277759 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277759#Comment_277759 Tue, 07 Jan 2020 10:13:41 +0000 Pile-o-Stone
Our shed is partially shaded in winter, early spring and late autumn when the sun is low behind some trees, so we fitted Tigo Optimisers to each panel which stops one shaded panel from bringing down the output of all the others in the string. They can be used with pretty much any inverter.

We fitted 6 x 300w panels on our woodshed and these seem to be pretty cost effective (you can get higher wattage, but much more expensive). If you fitted 10 x 300w you'd get a 3kW array, which is a reasonable system.

In winter, our panels are completely in shade due to the low height of the sun, but on really bright days we still get a few hundred watts from ambient light.

Just to check though before you go down this route, have you made sure with the council that they won't allow solar panels under any circumstances? Ours refused us at first but changed their minds when I pointed out that they were roof integrated, black panels with black frames and didn't stand out at all.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277760#Comment_277760 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277760#Comment_277760 Tue, 07 Jan 2020 10:15:15 +0000 owlman https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277762#Comment_277762 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277762#Comment_277762 Tue, 07 Jan 2020 10:59:50 +0000 djh Posted By: aclarkyI live in a conservation area and can't put solar PV on the roof.
I don't believe that's correct. e.g.:

https://www.quotatis.co.uk/advice/regulations/solar-panels/solar-panels-conservation-areas/

"Can I install solar panels in a conservation area?

"You can install solar panels in a conservation area. You can even do it without planning permission, but you do need to follow a number of rules. These include:

* "Not attaching solar panels to walls facing a road
* "Not installing stand alone solar panels in the area between your home and a road

"You’ll also need to follow the planning rules that apply to solar panel installations everywhere unless you want to make a planning permission application."]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277765#Comment_277765 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277765#Comment_277765 Tue, 07 Jan 2020 13:06:06 +0000 aclarky
Thanks pile-o-stone, looks like a good set-up!

cheers]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277768#Comment_277768 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277768#Comment_277768 Tue, 07 Jan 2020 15:10:54 +0000 djh Posted By: aclarkythis is in Glasgow
Ah, Scotland is different and more awkward apparently.

https://www.gov.scot/publications/guidance-householder-permitted-development-rights-9781780456836/pages/6/

See §4.61 onwards, especially §4.70 "There are no Class 2B permitted development rights in a conservation area." and also the legislation under §4.73 "In the case of dwellinghouses in a conservation area or within the curtilage of a listed building , the floor area of the ancillary building can not exceed 4 square metres." That doesn't give much area for PV panels.

There was a whole series of cases some years ago in England where people fought councils to be allowed to put PV on properties in conservation areas. TL;DR they won and the law was subsequently changed. I have no idea whether there's any kind of equivalent situation in Scotland. Maybe some of our Scottish residents can help?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277773#Comment_277773 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277773#Comment_277773 Tue, 07 Jan 2020 17:59:20 +0000 GreenPaddy
You could try a "pre-application" for £50, for the shed,include photo's of Pileofstones very sexy roof above, and see what they say.

This link to a PDF doc, is quite a straightforward guide, to permitted development, which you could use to help you design the shed and location, in terms of trying to keep it within, or close to, permitted dev guides, and so be less of a challenge to the planners when they view your application/pre-app.

https://www.gov.scot/binaries/content/documents/govscot/publications/advice-and-guidance/2016/06/guidance-householder-permitted-development-rights-9781780456836/documents/00502132-pdf/00502132-pdf/govscot%3Adocument/00502132.pdf

As for PV on your house, hard to be sure, but from the photo it looks like;

- not a lot of space for panels on the front southerly aspect
- very nice house that could be ruined visually with panels scattered across it
- not everyone is like us weirdos, and would likely drive on by having seen the "ugly" panels atop your roof, if they came to view your house for purchase (effectively a devaluation of your property)]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277800#Comment_277800 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277800#Comment_277800 Wed, 08 Jan 2020 13:22:15 +0000 aclarky
I am just about to re-roof and as I am changing from scottish slate --> spanish I have to apply for planning anyway, I was going to try and tag a shed on the same application so it could be 3m x 4 or something.

So to think about repayment timescales - how many kwh could a solar array with say 8 panels produce if they are less than optimally sited - side of west elevation of house, some shading. Is it a waste of cash?

thanks again]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277804#Comment_277804 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277804#Comment_277804 Wed, 08 Jan 2020 13:45:16 +0000 djh
There have been links to pvgis on here many times to calculate generation.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277805#Comment_277805 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277805#Comment_277805 Wed, 08 Jan 2020 14:00:31 +0000 GreenPaddy
You might use 30% of that yourself, so say 400kWh/yr.
Assume 15p/kWh that you would not be paying for that 400kWh, so £60/yr (in reduced energy bill).

I think the export payment is around 5p/kWh if you're supplier is set up to do the export payments (or chnage to one who does), so that's 5p for 1100kWh/yr = £55/yr

So £120 saving per year. You can play about with amount of energy produced, used at home, etc, etc, but if you double, or half £120/yr, it's not lots of cash.

You'd maybe be looking at £3000 to get it installed and hooked up with tariff meter, so 20 yr pay back. That's still 5% return. If you've money resting idly in the bank at less than 1%, do it as a low risk investment, and because you're at least doing something to reduce your footprint, but it's not a big money earner.

You might consider a cheaper install, that doesn't include the export metering/payment, so not a registered installer with those additional costs, and just divert the excess power you don't consume in the house into your hot water cyl, via your immersion. Plenty here think that's un-green, but you're using solar energy to create hot water, and not importing elect or burning gas. Your gas will be about 5p /kWh, so you're no worse off financially for losing the export payments.

Alternatively, spend the money insulating your house, and reduce your footprint that way. If you're re-roofing, what are you doing about insulation in that part of the house (ceilings, coombes, draughty eaves)?? If you have traditional sarking boards (likely) and you fit the right roofing membrane below the slates, you can fully fill the rafters with insulation, and NOT require the 50mm ventilated void, and all the drafts and cold air washing that brings with it.

Personally I'd focus very hard on those opportunities, rather than taking the obvious route of consuming more earth's resources to have solar PV, and meanwhile leaking heat/energy from a new part of the house fabric...
...just some thoughts, not tablets of stone
]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277815#Comment_277815 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277815#Comment_277815 Wed, 08 Jan 2020 19:00:08 +0000 WillInAberdeen
Just to be careful with the compound interest, if you invested £3000 for 20 years at 5%, you'd end up with 3k x 1.05^20 = £7960, compared with 20*120 =£2400 from the solar by GP's numbers. So the return from the solar panels is a lot less than 5%. They'd take 25years just to break even, before there's any return at all.. :-(

So as Paddy said, solar panels are not a good financial investment on not-ideal roofs, there's other ways to spend money on old houses with much better returns, that's where I got to too when looking at it.

Clearly there's other motivations for investing in solar beyond just the financials, this is GBF after all...

One idea I was considering, is to invest the money in a solar farm instead. The economy of scale means you get a whole lot more solar panels for your ££s than if you put them on your roof, and the output all goes to genuine use, so actually reduces CO2. No guarantee what the return is, but apparently is commercially viable, and you can sell your share on later without having to sell your house. I was looking at some commercial solar funds , but there are community projects too AFAIK.

(Usual disclaimer: nobody should believe investment advice from internet forums, ask a proper professional, depends on all kinds of circumstances, etc etc)]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277819#Comment_277819 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277819#Comment_277819 Wed, 08 Jan 2020 19:09:26 +0000 philedge Posted By: GreenPaddy

You might consider a cheaper install, that doesn't include the export metering/payment, so not a registered installer with those additional costs, and just divert the excess power you don't consume in the house into your hot water cyl, via your immersion. Plenty here think that's un-green, but you're using solar energy to create hot water, and not importing elect or burning gas.
https:///newforum/extensions/Vanillacons/smilies/standard/smile.gif" alt="" title="" >
I dont think the objections to using a PV diverter for water heating are that its un green but more that its taking the pee out of the FIT system and "public" money. That veiw is based on the FIT recipient receiving payments for unmetered export units but grabbing all surplus energy for their own use rather than exporting a reasonable proportion in return for the payments received.

If youre not on the FIT system and not getting paid for deemed export, then grab as much PV as you want of your own generation. Only criticism that could attract is it may not be the most efficient use of energy??]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277820#Comment_277820 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277820#Comment_277820 Wed, 08 Jan 2020 19:15:25 +0000 philedge Posted By: WillInAberdeen
One idea I was considering, is to invest the money in a solar farm instead. The economy of scale means you get a whole lot more solar panels for your ££s than if you put them on your roof, and the output all goes to genuine use, so actually reduces CO2. No guarantee what the return is, but apparently is commercially viable, and you can sell your share on later without having to sell your house. I was looking at some commercial solar funds , but there are community projects too AFAIK.

Hopefully its ok to post this and I have no interest in the business other than as an investor, but Abundance Investment have a range of green and ethical investments including solar farms, wind farms, tidal power etc.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277821#Comment_277821 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277821#Comment_277821 Wed, 08 Jan 2020 19:17:17 +0000 aclarky
Yes there is lots of attention needed for insulation. The roofer is (happy) to remove sarking on the hard to reach areas in the roof and insulate - how sure are you I can fill the rafter with insulation? I'd love to but most people suggest the 50mm gap. And as it is room in roof the attic space is vented from the eves so if I blocked that off I would need tile vents in the attic space?

I had considered if it would be possible to create a warm roof entirely?? any thoughts or is that a condensation time bomb/ridiculous expense?

thanks again]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277826#Comment_277826 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277826#Comment_277826 Wed, 08 Jan 2020 21:29:32 +0000 GreenPaddy
Be careful when using the term cold or warm roof. Warm roof (as I understand it) implies all or the majority of the insulation is to the outside of the structure. However, some times people refer to a roof space that's cold (flat ceiling insulation) as a cold roof, and a roof space where the insulation is between the rafters as a warm roof. Call it what you like, as long as everyone involved knows exactly what they are doing, and where interstitial condensation may or may not form, how it's prevented or vented.

I wouldn't suggest to clients to start by ripping off a roof to add insulation, but you're half way there already for other reasons. Actually I've a client near the Granite City who needs to replace their worn out cement tiles and knackered underfelt, and we're going to do the insulation from the outside at the same time. They started by decorating the inside of the house, then thought about insulating it, so ripping out decorated room plasterboard is a lot more costly and disruptive.

Solar PV payback, yes compound interest does impact the apparent cost, but the un-bought elect and export payments will also increase, so I tend to expect the two might even out a bit (too lazy to try to guess at both projections )]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277843#Comment_277843 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=277843#Comment_277843 Thu, 09 Jan 2020 13:42:46 +0000 Pile-o-Stone
However, your original idea of a DIY install on a shed roof, especially as it's such a large roof, could still be worth looking at, especially if you fit Tigo optimisers to reduce the impact of shading.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=278033#Comment_278033 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16386&Focus=278033#Comment_278033 Wed, 15 Jan 2020 16:15:03 +0000 TimSmall
Some combination of closed-cell EPDM, MS-polymer sealant, and butyl sealant, clamps and bolts could be used to make the panels into a convincing roof covering on their own.

With breather membrane underneath (use the type that is specced with high UV resistance e.g. the type used underneath hit+miss rainscreens on timber frame walls, and/or use two layers), this should remove the cost of the normal roof covering.

If you are designing the building around the panels, then you can overhang the connected panels a bit, and not even have any flashing at the edges of the panels to worry about...]]>