Nickfromwales

Minimum of £11k for a 4kWp system........

How did you get a price of £6k for 28kWh sized system?

Can you upload your plans? Not quite. Its the number of connected cells that dictates the discharge rate, which is then further 'choked' by the limit of the throughput of the BMS. It's the batteries that are the thing that slows down rates of charge and discharge. As above, no. Not very long! This will go up again after your initial 12 month contract with Octopus runs out. They will likely ask you to adopt a fixed rate tariff first, and then migrate you to the ToU tariff. The fixed will be >40p/kWh from the get-go. Correct. You would also be hammering the guts out the system every single day, so its lifespan would be reflected in that usage pattern. You would need to choose equipment that had a warranty based on unlimited throughput. Not even in the ball-park for a system such as the OP's requested capacity. Triple that, unless going for the cheapest of Chinese. @SBMS If AC coupled, have you yet done a DNO application? You would likely need a 3-ph solution, further increasing costs / complexity.

Deffo parge afaic, regardless of which woodcrete system. Just achieved 0.88 on one such build so "it can be done" Bolster that with Passive Purple / similar blower proof painted / brushed on ( liquid ) membrane for the tricky areas and junctions where timber meets ICF and you'll have great results. What stage are you in the build?

If you can convince yourself that you will self-consume at least the lions share of what you generate, then do as @ProDave @canalsiderenovation and others have done and DIY for as cheap as you possibly can. Any decent electrician should be able to do this from start to finish. Installing the trays / mountings etc couldn't be easier, but a roofer cannot run DC cabling and make off MC4's so I would not pursue that advice tbh.

For anyone not well versed in this, and for pretty much guaranteed results, this is a good option. Fast, good airtightness, and walls can be made arrow straight. Fortify this with tapes / membranes and you'll achieve great results.

Be careful what you say to him.....as he'll talk you into an apprenticeship!

Link These are what I use for a retro-fit where gas vs UFH is the remit and space is tight as they are wall-mounted. The 25 and 50L show as out of stock, so ask about availability. Other sellers are punting the same unit out for more money. Telford are now doing small buffer tanks, so if you require such a unit, contact Trevor from Cylinders2go and mention the forum and he will give you a discount.

Read the small print Over 60's are 5%, and under 60's need to have left 60% of the installation cost ( in materials ) behind to attract 5%. That's assets only, and doesn't include labour / scaffolding etc. Best to check your individual eligibility first.

How are you 5% VAT? Is this part of a large refurbishment?

I have found these to be rather complicated and somewhat unreliable tbh. I won't be using that system ever again ( and I've been installing central heating for nearly 30 years now ). Have a good read of the existing content here first, as this has been discussed quite comprehensively. You will definitely need to introduce a buffer tank to this setup to allow the UFH to run independently and reliably without short-cycling the boiler. Do you know if there is any insulation in the existing floors / walls? What is in the attic?

@Pinzameld Check out @Crofters blogs / posts. He’s done a demountable building under the same guidelines iirc.

Have many on here had comparative costs to go from a regular foundation system ( block and beam over trench or the type of system linked a few posts back ) vs a passive raft ( assuming screw piles are not required in each instance )?

It is a bridge over the possibly unstable ground in between the trenches. A raft over trenches in essence. It also gives a uniform level platform for the insulation to sit on too. Not necessarily a problem with a poured floor / screed, but a nice surface to work from nonetheless. Ground conditions are everything with foundation designs so proposals will differ site to site.

Yup. Male / female arrangement also, so no 'male' end on the light fitting itself can be touched when live and no connector inserted eg end of line fitting.

Agreed, and known. Yet OP pic shows that tooth which may be a manufacturer specific plug / connector vs the 'fits into anything, any way around' figure of 8 , and therefore it is likely the Interna plug / connectors will not go into the TLC fittings. Added for info so the OP can decide the best path.

I think it’s assumed that the overlay would either be a compromise / get out of jail solution, or would be atop an already insulated substrate. Let’s not get our knickers in a twist over a retrofit solution “it is what it is”.

Hence my phrasing “not necessarily”

Not necessarily. If it’s a 30mm system atop a 100mm layer of PIR or PUR then it’s a very efficient solution for the OP. Prob need to self level the block and beam to get a flat, uniform surface, so maybe allow 10-15mm worst case for that.

Usually only doubled up at the bottom courses but time will tell!

The item in the OP looks to be a polarity-conscious connector, whereas the figure of 8 is not? TLC offering is difficult to say from pics. Shouldn't really matter tbh but the OP item may need the leads cutting to create a hybrid interlink.

You'd have had to dig out regardless, for a decent sub-structure for the overlay to go atop. You'd have tried to make the overlay panels yourself, and we'd still be tiling if you went that way The overlay needs a solid structure or it'll all disintegrate.

What is the intended floor covering? Porcelain tiles? If so you can get an overlay system and have all insulation. https://www.wundagroup.com/underfloor-heating/wundatherm/the-system/

@Tyler Check out TLC directs offering https://www.tlc-direct.co.uk/Main_Index/Lighting_Menu_Index/Lighting_Kitchen_Index/Linkable_Flourescent_Fitting/index.html