Thorfun

but the Solaredge batteries can't be islanded, right? so in a power cut you're limited to the PW2?

hmm...yeah. maybe I'll investigate getting an installer to do it and zero rate it. then I don't have to worry about reclaiming VAT. too many options and too many things going around my head!

I'm not sure, was just voicing concerns in response to other posts about batteries not being zero rated unless supplied as part of the PV. also our battery solution will most likely be supply only so I'll have to claim back from HMRC post completion (assuming I go down that route!). tbh, I have so much else to do and worry about that I'm trying not to think too much about the batteries and am giving it thought cycles as and when I have them spare.

thanks Dan. appreciate it. so my 9.5k isn't too far off the mark. I still think I'll go down the Lux Power and Pylontech route as I can't really afford 9.5k (and maybe + VAT as my PV is already installed as well) at the moment!

I'd be really interested, if you didn't mind sharing, what your quotes for the PW2 and install is when you get it. my recent quote was £9500 exc VAT which had gone up from £7500 18 months ago. not sure if the installer is taking the Mickey/doesn't want the job or that is now the going rate.

ok. I guess that's one for your structural engineer.

Happy wife, happy life! 😂 (Happy partner, happy life doesn't really work though, sorry.)

I don't get how your system is, in essence, any different to a SIPS panel or a twin-wall system? again to refer to MBC's drawings https://www.mbctimberframe.co.uk/passive-house/passive-wall/

wish I knew what you said now!

that's the thing isn't it. going to get my sparkie to install the battery system. Solar PV is already installed as per that G99 application. then the M&E consultants got taken over and are no longer doing batteries and so gave me a refund for the PW2 and dumped me to find someone else to do the work. that's what led me down this path! so I don't have an installer any more.

spoke to UKPN and they said new G99 application. guess I'll Google how to do that (after searching on here first of course. 😉 )

isn't loft roll for horizontal usage? might sag if installed vertically or diagonally between rafters? also you have to compare the lamda values of each. they may be different and so will need different thicknesses of each to get the same U-value.

I was talking about insulation below the slab. here's an example that many have on here offered by MBC https://www.mbctimberframe.co.uk/passive-house/passive-foundations/

don't forget the emotional cost of going for a flooring that you don't really want! if you'd wanted LVT then you'd have specified it to start with, right? so ditching the tiles (which is what you wanted) for LVT (which you didn't)* will have an emotional cost and impact. you might forever be thinking you really wished you had tiles? not sure you can put a financial cost on that. * assumed due to original decisions made about floor coverings

a whole new G99 application though? I've never done one of those before. 🤔

can't you just ask the tiler to install them and tell him you accept any risk in 'that area'?

on the subject of informing DNO....our G99 application that has been approved has this: if I'm not going for the PW2 any more but using another battery storage solution do I still need to inform the DNO? if so, is that a whole new G99 application?

ref: External timber cladding - 3rd edition; Patrick Hislop, Peter Kaczmar and Lewis Taylor; TRADA publication

+1. and this is a Trada guideline as well. (actually I think they say 200mm - 250mm, I'll go grab the book and check!)

I'm not as knowledgable about this stuff as those already commented but if you're going back to the drawing board can you not design it with an insulated slab? that way you can sit the cassette on top of the slab as recommended and have loads of EPS insulation below ground to reduce thermal bridging. unless I've completely got the wrong end of the stick here of course.

I disagree with this at current prices. I have been quoted £9500+VAT for a PW2 installed. if we ignore VAT as I'm a new build that would be £703/kWh. And with a system like @MikeGrahamT21's (and what I'm considering) the price per kWh gets cheaper with the more storage you add as quite a bit of the cost is the inverter. so if he adds the US2000C adding 2.4kWh to his storage array his £/kWh goes down to £542. it's why I can't justify a PW2 at the moment. oh....and the 9 month lead time on the PW2 units!

I'm not going to lie to you, my arms hurt! I did the final 9 holes this morning which took about 90mins and by the end of it I was covered in dust and could barely lift the core drill. but it's done now and I have lovely pretty round holes. 🙂

and Isover Batts from Jewsons. I got a good price on my 32 batts when compared to Knauff stuff.

yes, it was slow (although not as slow as I thought it'd be after reading your experiences!) and very dusty (which isn't really an issue for me as I'm in the dungeon and nothing else is down there) but wasn't that bad at all. I managed to do 10 holes today and have another 9 to do tomorrow. I could've easily done it all today but I also have a day job that takes up most of my time! I'm going through dense concrete blocks and used a Screwfix/Erbauer 107mm diamond core drill bit (https://www.screwfix.com/p/erbauer-diamond-core-drill-bit-107mm/1121v). what was it you were core drilling again?

there was a good thread if I remember correctly on this subject that gave me lots of ideas (assuming I understand your dilemma)