I'm not certain what we are going to do about solar panels. (One thought is solar water heating & wood stove with back boiler & accumulator tank, and gas condensing combi boiler back-up - but I'm not sure how these integrate, or if the wood stove is smart in terms of lifestyle and/or location of wood fuel long term).

We are at the point of submitting a planning application for extension, which also includes reference to EWI, sunpipe, new window &c. It makes sense to me that we should to include solar panels in this planning application, notwithstanding that they are meant to be permitted development.

That's because of the experience of someone on this forum that planning challenges are made retrospectively and also because our area is likely to become a conservation area (the report into whether it should be is being drawn up now). My understanding is that if I have existing planning permission that includes solar panels then I can fit them at any time after starting the work (i.e. from when bco has inspected foundations for the extension), even if we end up being in a conservation area in the meantime.

It is hard to say what our heating needs will be post-insulation, but is there a 'rough and ready' calculation I can do for solar panel size for water heating that would allow me to just go ahead an draw a couple of appropriately-sized rectangles on the roof for the purpose of the planning application?

Thanks for that, that's brilliant. Their table says I need 5 m2 of panel for hot water (is that year round - and if so, do you end up with excess hot water in summer?) so that's a start.

I can't quite see how to adapt their graph for space heating (probably a call to them is in order). Anyhow, the roof surface I have available is under 16 m2, quite a shallow pitch (30 degrees or maybe a bit less) and South-east facing. I don't think I'll get planning permission to cover the entire roof (although maybe I should try!) and there is no point over-sizing solar water heating since I can't export. Perhaps I should ultimately aim to have solar water and solar PV side by side?

Best bet is probably to just draw on the maximum I reckon I can get away with.

The situation relating to the planning permission is as follows: (obviuosly you need to satisfy yourself - but I have provided a link for you to the regs)

1. You only need planning permission for a solar panel on your house if:

(a) the solar PV or solar thermal equipment would protrude more than 200 millimetres beyond the plane of the wall or the roof slope when measured from the perpendicular with the external surface of the wall or roof slope;
(b) it would result in the highest part of the solar PV or solar thermal equipment being higher than the highest part of the roof (excluding any chimney);

2. Retrospective challeges can only be made if the development requires PP. So providing you meet the regs you will be ok.

3. If it is not a conservation area when erected or planning permission granted, then regs relating to the conservation will not apply. So if your panel is included as part of a PP you can implement whenever you like providing development is started within the 5 year period. If it has become a conservation area in that period - it will not affect the permission.

4. If it does become a Conservation area before you either erect the panel or make the application then the situation changes:

In the case of land within a conservation area or which is a World Heritage Site, the solar PV or solar thermal equipment would be installed—
(i) on a wall or roof slope forming the principal or side elevation of the dwellinghouse and would be visible from a highway; or
(ii) on a wall or roof slope of a building within the curtilage of the dwellinghouse and would be visible from a highway; or
(d) the solar PV or solar thermal equipment would be installed on a building within the curtilage of the dwellinghouse if the dwellinghouse is a listed building.


If i doubt include it in the plannig applaication if you are making one anyway. But you need to check if you need PP for the extension 1st - you may not!
Hope this helps.

Regs set out in GDO 2008 (there may be a few slight amendments since then, but I guess minor. the link to the PDF is:
http://www.solaressence.co.uk/downloads/uksi_20080675_en.pdf
RR

more info needed really

ie, flat panel or tube (I'd advise in roof flat panel for a planning ap in soon to be conservation area), and how many people in the house / bathrooms connected to the hotwater etc.

but ball park, for a house with 2-4 or 4-6 people (depending on hot water usage) if you're talking flat panel would be either 4 or 6m2 generally, in roughly 2.1*2.2m or 2.1*3.3 m configurations (to give a bit of leeway for interpanel fixings / slightly bigger panels etc).

not much point oversizing too much on that angle of slope because you're perfect for summer, and not so good for the rest of the year, so oversizing will just give you way too much in summer, and still not a lot in winter

once you allow a bit of room around the edges for roof ladders, not overhanging the guttering / overtopping the roof, I doubt you're going to have room for much solar PV, but I suppose you could maybe get 600-1000 watts up there as well depending on configuration and if you go for 4/6m2 of solar thermal. If you have a decent size south ish facing wall (probably not facing the street), you could be better using that for an oversized solar thermal system, and using the entire roof for pv, but that's probably not applicable.

what's the logic of them not liking in roof systems?

The only thing I can think of would be that it's not as easy to remove and reinstate the original look of the house with them, but in terms of actual visual impact they're surely less obtrusive, and closer to the look of velux windows.

also worth remembering that even though it's a permitted development, the fact it is a conservation area would increase the areas perceived amenity value for the purposes of working out what is and isn't reasonably practicable in terms of siting and (to some extent panel type_, to the point where it could well be judged to mean that speccing flat panels instead of tubes was a reasonable compromise of systems performance and cost to have to retain a greater amount of amenity value in the look and feel of the area. Technically it only refers to the siting of the panels rather than the equipment type, but what may be judged a reasonable siting for flat panels may be different to what may be judged reasonable for siting evac tubes, so in reality IMO the choice of technology type is implicit in the legislation even though it's not specified.