Thorfun

underground in a 110mm twin-wall duct from the cabinet to plant room in the basement.

ahh....(firstly I must apologise for not giving all the facts)....even though we have a 3-phase supply trying to get a 3-phase meter is next to impossible so I haven't bothered yet. again, as the whole house is being run off a single phase we are having a single phase smart meter installed in a couple of weeks (hence getting the cabinet and CU in ready for that to happen) and then, in the future, we can upgrade to a 3P meter when they become available again and if we deem it necessary. but I want the SWA cable in place from the cabinet to the CU to be able to handle 3P if/when it happens. yes, we could potentially fit more PV but I've pretty much run out of roof space! so the 10.5kWp is enough for us for now I think. and we already have a single phase inverter here and paid for as I've always only ever wanted to run the house off a single phase. I wanted to avoid the complication of running a house across 3 phases, having a battery that spans 3 phases or 3 battery storage systems (one for each phase) and wanted to avoid any risk of arcing across the phases no matter how small that risk might be.

our house is 420m2-ish in total. our M&E consultants wanted to give us 2 x units but I fought against it as didn't want double the running costs, double the maintenance etc. in the end they designed a system that worked with a single Q600 and 90mm semi-rigid ducting. it's not commissioned yet though but they promise me the flow rates will work.

Hi Peter. I fail to see how it's irrelevant. my PV inverter is on a single phase and so feeds back to my CU on that single phase. the electricity generated by the PV can only be utilised on that phase so if our ASHP is on another phase then how can the PV generated electricity power it? afaik the only way is to ensure that net metering is in place so that any power drawn by the ASHP on a second phase will be cancelled out by the exported electricity on the first phase. unless I'm completely misunderstanding this whole thing!

could you fit external blinds or shading to reduce the solar gain whilst allowing you to keep the large windows and views? might alleviate the need for active cooling. although, we're having AC and also have external blinds so if you want it go for it.

we do have a big cabinet (https://ccf-fibreglass.co.uk/products/electric-kiosk-housing-meter-box-cabinets-enclosure-grp) so the size of the TP&N isn't an issue. the reason for running everything off a single phase is our Solar PV inverter is single phase and batteries will be on the single phase and so I didn't want to complicate matters by having different phases in the house/garage. we have a room above the garage as well so that is part of the house really. and the garage is attached to the house. our electrician said, as our cabinet is about 25m from the CU we're on the cusp of 25mm and suggested going up to 35mm which I'm fine with, just in case. we have an 11kW ASHP (Mitsubishi Ecodan) which, again, I will want to power from our single phase PV array. in theory, I don't yet need to run cables/isolators etc for 3-phase but I'd rather do it now than running for a single phase and then needing/wanting to utilise the 3-phase later down the line and having to run more cables/install more isolators then. hope that makes sense! it does in my mind. 😉

DNO installed 3 x 100A head. our electrician has sized 35mm 4-core SWA with a separate 35mm earth. our system is a TT earthing system so I will be hammering an earthing rod in to the ground in the not too distant future! we're planning on running the house off a single phase but I am planning on utilising 3-phase in the future for EV charging, mostly. so am running the cable for future proofing. I also need a TP&N switch fused isolator which isn't cheap.

I need approx 30m of 4 core 35mm SWA cable for the connection from the cabinet to the CU in the plant room (damn that stuff is expensive!). I've been doing my research and have found on superlecdirect.com their LSZH SWA cable is £1.01+VAT cheaper per meter (https://www.superlecdirect.com/cables/steel-wire-armoured-cables-bs6724-lszh/bs6724-35mm-4core-xlpe-swa-lszh-cable-harmonised-black/) compared to the PVC version (https://www.superlecdirect.com/cables/steel-wire-armoured-cables-bs5467-pvc/6944x-35mm-4core-bs5467-xlpe-swa-pvc-cable-harmonised-black/). My electrician said that he's previously used LSF cable and it's a pig to strip and as my SWA is going in a duct in the ground he said just get the PVC stuff. But LSF is different to LSZH, right? so is the LSZH cable also a pig to strip? And if the LSZH cable is cheaper than the PVC why wouldn't you buy it? it's better, right? am I missing something here? I have a LOT of cable to buy and will be agonising over the whole LSZH/LSOH vs PVC argument lots in the near future. can someone also please tell me if it's worth using the LSZH stuff even if it's more expensive than PVC? I would've thought that in a domestic environment by the time the cable catches fire, i.e. has gone through the plasterboard, I've got bigger issues than the PVC burning, right? is LSZH more for commercial buildings when you have to evacuate a multi-storey office block or high-rise buildings like apartment blocks etc Can someone please help to clear up this whole issue for me? 🙂

I predict £2 million. with all those curves and curved glazing and cantilevers with a grand designs finish it's gotta be at least £2.5k/m2. then add costs for **** ups along the way.

https://www.granddesignsmagazine.com/grand-designs-houses/grand-designs-new-series-2022/?utm_medium=email&utm_term=&utm_content=READ MORE&utm_source=Grand Designs Magazine&utm_campaign=New TV series coming soon! Here's what to expect... I'm particularly interested to see how a three-storey, 5 bed, 7 bathroom curved cantilevered 700m2 house with an initial budget of £700k turns out! 😂

all joking aside, I wish I could help. we did originally have light wells planned for our basement with walk-on glazing at ground level but in the end decided that it was just too expensive and those rooms in the basement didn't need natural light so I never did any real research on the subject. good luck though, and I genuinely mean that. 🙂

well that's a first!

I can recommend getting one of these first https://www.screwfix.com/c/tools/tape-measures/cat831176

so you have a 3 phase electricity connection? is your PV inverter 3-phase as well? I thought that if you have 3-phase electricity you can get 3.68kWp array on each phase so, in essence, 11kWp without G99 application. we have a 3-phase electricity connection but I was lucky and the DNO approved our 10.5kWp array AND a Powerwall 2 on a single phase so I don't have the headache of net metering for running the house as that will be on a single phase. only issue might be if/when I get a 3-phase EV charger then I'd need to ensure that net metering was working.

@Wil do you have DNO approval for 2 x PW2s? I know that @pocster wanted to put a second PW2 in but the DNO wouldn't allow it so had to go with a hybrid PW2/StoreEdge solution which he's been having a few teething issues with. I'm inclined to agree with @Dan F and suggest a single PW2 for now with only the 5kWp array and see if that works for you. if you find that you need the extra PW2 then take a look at it. £7400 pays for a lot of electricity especially when it's currently only 7p more than the E7 rate. if you had a larger PV array and could use the sun to fill both batteries then I'd say it would be more worth it. ultimately, it's up to you! and whether you're completely hung up on the whole 'pay-back' period. personally I never considered that when I plumped for our 10.5kWp array and battery solution. it wasn't about pay-back period it's more about reducing my reliance on the grid.

cheers and, yes, it's going in a GRP cabinet. sounds like a fair compromise between cost and quality. I was thinking that either the Lewden or the Contactum would be the ones to go for as a middle of the range type unit.

our electricity supply is on our boundary and the plant room about 25m away, as such I believe I need a switched fuse isolator installed in the cabinet (confirmed by my electrician). I've been looking at my options here and the price difference varies dramatically! e.g. https://www.gil-lec.co.uk/hager-jfe310u-fuse-switch-tpn-enclosed-100a - This Hager one is £450+VAT https://www.cef.co.uk/catalogue/products/4920299-100a-tp-n-metal-fused-switch - This Lewden one is £278+VAT https://www.electricaldirect.co.uk/product/contactum-100a-met-tpn-fused-switch-disconnector-648206 - This Contactum one is £205+VAT https://www.electricaldirect.co.uk/product/ced-100a-3-phase-tpn-fused-switch-disconnector-671368 - This CED one is £156+VAT I haven't included the ludicrously priced Eaton units! Can anyone please tell me if these are all the same in terms of quality and safety? We have a TT earthing system if that matters as my electrician says that due to the resistance of the TT system we would be hard pressed to ever blow a 100A fuse and we have 2 options with the TT system, 1. RCBOs throughout (my chosen method) 2. a time-delay 100mA RCB. So, if we're never likely to trip the 100A fuse why would I want to pay large amounts of money for a Hager isolator if the CED one does just as good a job?

it better, coz I ain't taking it off! 😉

It’s not installed yet so I can’t comment on the performance yet. Do a search on Pylontech and you’ll see others’ experiences.

Just FYI, the system I bought was around £4k + VAT (parts only) if that helps. 6.4kWh storage that is very expandable if required. Simply plug another (or more) battery in to get more storage others have also gone down the Pylontech route which offers similar results/costs.

I was quoted £9500 + VAT in March 2022 so could be anywhere upward of that by now! also, you won't find one for love nor money. I was quoted 12 months lead time. I did post a news article alluding to changes coming with Powerwalls later this year so maybe stock is so low because they're getting ready for a new model? or maybe at least a change on the PW2? if you're dead set on a Powerwall then maybe wait a few months. I decided to bin the idea of the PW2 and have gone a different route.

send your plans to MBC (or other TF companies that offer the same product!) and ask for a quote! they have in-house designers who should be able to translate your existing plans to a TF house afaik. it might add a small delay but the build is so quick with TF that you'd probably make up any delay in build time.

our architect designed a window that didn't work. it was floor to ceiling(-ish) overlooking a flat roof but they didn't take into consideration the insulation of the flat roof and so the window was below the level of the deck. in the end we had to build up the level in the wall to be above the roof and order a new window (only about £700 for us as we managed to tag it on to the existing order that hadn't shipped yet). we made a hole in a wall in another part of the house and used the original window there. so it wasn't wasted money for us just an extra expense that we weren't expecting but on the plus side we had another window looking into the woods surrounding us! I, not once, thought to sue or claim for the expense of that window from the architects but I've been told that I'm too nice! I also didn't want to sour our relationship with the architects over that amount of money. I felt it was a small price to pay for a minor inconvenience. obviously, for you it's a lot more money so would be harder to swallow the loss and a much bigger inconvenience! I can't advise whether the architect is at fault but it sounds like their disclaimer covers them. I guess you need to figure out if the legal costs for pursuing the claim will make it worthwhile if you believe you've a chance to win. people make mistakes and sometimes just need to be forgiven and move on. good luck with whatever you decide to do and it's a shame that this happened.

welcome! sounds like you've been at your renovation as long as @Onoff has been doing his bathroom. hope you find the information that you're looking for. it is a great source of knowledge.

🤣 take a look at the MBC passive house twin wall system with pumped in cellulose. according to those that have them they're VERY quiet internally as the 300mm cellulose really dampens down the external noise. (other companies are available to do this sort of twin wall pumped cellulose build)