Muellar

Thank you all for the input. Hope you've managed to have a lovely Christmas and New Year... I've put the effort in too and @SteamyTea i've adapted what you sent to me but only because I'd got the devices and loadings already mapped out given the room layouts and my thinking behind what would be used in each area. So here's my workings, warts and all on the basis of @SteamyTea and his rationale as well as applying BS7671 methodology to what I would suggest as being the ring ciruits just from my gut feeling using a video I saw. As a summary of the sheet: Using @SteamyTea principles I get total daily KW of 7.3 in winter and 4.5 in summer Applying the same number/wattage of devices and using BS7671 I get a total need of 42kVA If i take into account all the considered opinions, i'd take 25% of BS7671 as being most likely demand, so about 10kVA say in winter... It does show the demand that comes out from ASHP purely due to it's wattage rating alone and the application of the code. Heating and cooking is about 50% of the kVA using the code and applying the diversity rules. Maybe i've got it wrong, but without taking a course I feel i've applied it fairly closely. Interestingly, I found this really useful videa on youtube, https://youtu.be/7MhH-k6pEgI and the big takeaway I took from this was as the guy points out, that even in BS7671 it states it's impossible to work out. There's been other things i've seen where an electrician even pointed out that using the code his home installation woudl be illegal, but in reality it actually consumes about 1/3 of what the code would produce, even on a winter day with his kids leaving lights on! So I'm going to stop now and share my workings, but this has all given me the logic to go to NIE and state I don't need a 40kVA 3 phase supply and may maybe not need one at all if I go off-grid, but what would they charge for a 100amp supply and see what they come back with. However the more I've looked at this the keener I am to try and not connect to grid, have a mixed supply (PV, Ridgeblade, Log burner with heat exchanger and a back-up generator etc) and to log it all so anyone can see how well it works. Hope this is helpful/useful to others as i'm very grateful for your input. Electrical workings and key figures_01.01.25.xlsx

Now I'd originally thought of having something like that, but was told 'don't be silly'. i'd seen a Woodfire EX15 that i'd quite liked, and had seen that not only would it be a nice feature, but we'd also have back up should things go bad - like recently during the storms and power went down. This whole experience with the cost of power has really made me think that maybe i'd dump the whole induction hob thing and go with Calor gas tank for cooking use and also a boiler to be used now and then, with adding in the Woodfire EX15 for use during winter and as a back-up. Then go back to NIE and ask 'how little can you give me' just for small power and other items.

Yes, Northern Ireland Electricity. I've made my own attempt at a sheet but I got an even larger figure... duh. Thanks for offering to knock one up for me, i'm very grateful.

lol... you've reminded me of a Father Ted sketch @Conor, thank you! And yes, it's how I felt when I saw the calcs come through I just couldn't believe the figures being presented but they stood by their calcs and this is an area I get confused in so I left them to their stuff being told by the architect they were good and could 'work wonders with NIE'.... unfortunately not the wonder I'd hoped for.

I assume so as the engineer did all the dealings. I've seen he's said that NIE will want to upgrade the transformer to a 50kVA regardless of what we want as it's currently at capacity. He said that a home such as ours from his experience would need 35-40kVA and we can have that but as single phase, not 3 phase. My conclusion is that NIE are holding a gun to my head now as they want me to pay for a transformer upgrade even though i'll only be 1 of say 20 properties drawing off it of which several are farms with milking parlours!

hope you're sitting down.... engineer came up with peak demand of 40,000 watts, so suggested a 3 phase supply of 41 kVa. I'm being told that I can have all the supply needed but as a single phase and not three phase supply. I reckon this is why the cost is as high as it is.

I tried this and got myself in a pickle. Created various spreadsheets and am now completely confused by the whole thing which seems to be a bit of a dark art to me. My current view though is given the feedback, is that i'm very tempted by the micro CHP route and getting a Calor gas tank put in. That way I transfer all the heating load and electricity gen to that particularly during the winter months when the PHPP calcs show the need. Once we are outside of Nov/Feb the heating need drops off, then CHP would decrease till we get sufficient from the PV/Batteries.

It is up on a hill but NIE have said they need to replace the whole transformer and want to charge me for that as opposed to just adding in my portion so they are playing a game in my view with me as i'd heard the transformer was up for replacement in any case. Now i've been looking into this seriously I'm tempted to go the CHP route that @SteamyTea mentions and using that at least for all the heating. To me it makes sense as winter months is when I would need the heating and is when PV output would be lowest, so having CHP doing that at least would be the way to go. If that get's me below a threshold then great, maybe NIE will see sense. Moving the house isn't possible.

We've got 300m2 so I guess size is maybe the issue as we've got a very low overall need for heating as a result of the ICF/Flooring/Roof and glazing (most glazing on South/West). All indications were we only needed a 6-7kw ASHP. The micro CHP may be the way to go given the cost NIE are wanting to upgrade the transformer and lay in the new supply @£35k. it may be that I just have to 'suck it up' but I feel they want a silly amount for what is a well designed home.

Thanks @SteamyTea... i've already got a quote for 5.22kw PV array with 2x batteries/inverters etc, but that won't deliver that amount all the time so I'd thought of adding in a wind turbine as we are on a hillside. I see there's micro CHP which could be a route as that would supply the heating/hot water so woudl offset what the ASHP would have consumed. Ideally I need to find someone who can do a proper calculation on the power needed so I have that with more certainty that the bowl of porridge it currently is for me!

£35k to have the connection to the grid via NIE who want to upgrade the local transformer.

Hi I've had a crazy quote for power supply and wondered if anyone has had experience of going totally off-grid at least for electricity supply and if there's someone you've known of who's been able to solution up a whole system? I'd already got plans to put in a 5.2kW pv array with battery packs etc and I'm thinking i'd be happy to go with the extra cost of a wind turbine (which will need planning) and then a back-up generator, but i'm lost as to how to work out the calculations with any degree of accuracy. Merry Christmas and best wishes for 2025. David

I should have added that I the main bed will have a balcony so the windows are quite set back, same for the larger 8.4m so we'll also look at practicalities of shading as we get more into it but I guess you can only design so much out/in. Not sure if you saw my original post when I joined, but we've got these windows all there becuase of the view out over Lough Neagh. We did toy with reducing window area, but we felt we'd just ruin the point of building where we would be, and thermal gain/overheating was on the top of my worry list. But great that you mentioned it. Thanks.

I did wonder about that JohnMo, however the PHPP came up with no issues on overheating when I put in the stats for natural ventilation and as we're on a hillside outside Antrim we can readily open up and ventilate - fly screens needed! I'd seen more benefit from the heat gains in late autumn/winter/spring than a risk on overheating given location (temp/wind) and the limited days of sun/warmth we have. lol

@Nickfromwales@JohnMo sound advice and is what i've done previously, it'll be intersting to see the relvative cost difference between D/TG from the same supplier, that is where I'd be looking at the pricing in detail than purely going for a cheap set of windows. Interesting comments on bi-fold v sliding. My head was in the place that sliding would be more water/air-tight than bifold (fewer moving parts/less seals etc).. Your 'bifold over sliders every damn day' has got me thinking. Just to give you some context, we have 3 main large openings. Main bed = 5.5m, Kitchen/Dining/Lounge = 8.4m and Rear onto patio = 4.4m. Our SE has managed to design in a beam so the 8.4m opening can be clear span.