DevonBarn

@JohnMo that was for a 16.3kW GSHP. Yes floor will be well insulated, concrete base. @Alan Ambrose actually with respect the aim isn't to use less energy, it's to generate as much as we use (in £), so 3-phase just makes things more flexible. But point taken about complexity.

Thanks @AliG so this getting into the detail - that link in my first post is really good, goes into the details re: location/angles/temps everything so I'm pretty confident on what output we could expect on any given kW system. You're right it's entirely dependent on import/export prices, but like you say even if there's a large change, it seems to be about 50% export to import price, so you still need to generate the same in the summer to cover the winter, probably. If we're installing PV and all the gubbins really we should be installing as many panels as we're allowed to.. so @Rob99 I'll find out about 3 phase costs. I need to get more quotes in so we're not shooting in the dark, (just had a quote in for GSHP supply only £25k, and that's without digging the 1.2m trench?!). I'm speaking to a ASHP company tomorrow I'll update the thread. Also @HughF thanks for the suggestion, Multi head mini-split does look like a good and easy additional option

@SteamyTea 16MWh would definitely be preferable, I'll put that into the PVGIS later. I guess everything is 'off grid' down there. Thanks @Conor and @Thorfun I need to reassess annual demand, especially if 30kW system isn't possible and we need to make do with single phase.

Thanks @joe90, no we'd definitely do with a bit of overhang for the bi folds next time, we might get one of those sails. They are great for heat generally, but there were a few days last summer where we had curtains draped over the outside of the bi folds! Also noted re: ASHP, I need to get a few more quotes in. Hi @Iceverge that's really useful thanks, I'll plug that in to the spreadsheet, should get me a better estimate. Also do you know how to find @Marvin's AIM APE? Also what's AIM? And what's APE?!😅

That's really interesting, when you say 'cope' how are you heating yours?

@Alan Ambrose Thanks for the graph Alan, no realistically we'll be buying in most of our electricity for heating in the winter (eg December, demand 3500 kWh, PV output 500 kWh). But as it would be such a large system, we'd be selling enough electricity back to the grid in the summer to pay for the winter use, at the prices paid / charged by Octopus. @saveasteading Yes that's it, expensive compared to eg Gas, but covered by the income from the summer months. @Thorfun Hi, yes I think it sounds crazy too, but why?! And yes we would be using off peak in the winter to charge batteries but they're a drop in the ocean compared to heating demand. Re: ASHP - it's fair to say they have mixed reviews, especially when you need them most when it's freezing. But we haven't ruled them out! And yes we will be insulating/draft proofing to n'th degree as well, so I'm hoping the annual demand is way below the current estimate.

Hi, I used the energy use for our current house (mostly solid wall old cottage with single storey extension).. Surely it would be better than this in a new build! Peak heating load: I've only got monthly kWh figures but worst is Dec: 3500 kWh for the month. For ref: According to the site above I'd only get about 500 kWh from a 30kW system in Dec. Annual demand: 23,500kWh / year. It's painful even writing it! Honestly hadn't considered MVHR, thanks I'll look into it.

Hi, true they aren't cheap (£250/rad) but cheaper than ASHP, and more importantly they'll definitely work when you really need them. Sustainable if the elec was ""green"", and pretty much 100% efficient (almost any energy loss is lost as.. heat).

Thanks Ali, yes we aren't sure we'd get permission esp on single phase. I read that paying for connecting 3 phase is possible, maybe around the £8k mark but all dependent on site? Thanks re: quotes, the £32k included 2 inverters and batteries but nothing that would handle heating. We'd just be buying in elec in the winter, which would be covered cost wise by selling 2x the elec in the summer. The initial quote for heat pump was for ground source but yes I'll be getting more quotes for sure!

Hi Conor, it's not so much whether a 30kW system would have the capacity (although that is a valid second question), but whether relying on buying in elec for winter heating is OTT? The bi folds should be ok in winter (we've got smaller south facing triple glazed where we are currently), but you're right in the summer, gets pretty toasty so we are thinking of shading solutions. For ref: - details of the fabric of the build, - really well insulated cavity, pre-fab tata insulated roof panels, all new windows and doors so draughts shouldn't be an issue. - energy storage - electric / immersion - energy demand - it's a large 5 bed house, ignoring car charging at this stage.

Hi, we're planning a large barn conversion and I'd like some neutral advice on the energy system and heating. It's about 400sqm and going through the calcs on aspect, location etc, I think I need somewhere between 30-40kW to cover all energy needed throughout the year if we want to get it to zero ongoing cost. This would mean making much more than we needed, and assumes selling electricity back to eg Octopus for 15p and buying it for 30p when needed. But, the idea of heating a barn in winter with electric radiators.. isn't this mad?! The sums add up but the common sense rings alarm bells. I like the simplicity, low installation costs and controllability of electric radiators, and I don't want to have to have solid flooring for heat pumps to work effectively. An estimate for a 30kW system here is around £32k. It sounds like an air source heat pump added to this would double the price. It's currently single phase. It may be possible to connect up a nearby 3-phase supply. Advice please! Has this sort of scale PV been done for a single house? Many thanks, Dan Ref: This is the website I used to calc PV needed for X kWh: https://re.jrc.ec.europa.eu/pvg_tools/en/

Hi everyone, we're hoping to convert a large (400sqm) barn into a house, with most of the work done by an experienced builder but I'll be helping where I can (experienced DIYer but need pointing in the right direction). The attached is the kind of thing we're aiming for.