@chickenbig You could also use the Ecofurb site South Cambs links to for a cost estimates for a whole series of improvements for your property.  I don't know if it works for Cambridge itself but for South Cambs, they seem to have a fair bit of the basic data on your home already, perhaps from EPC.

If you need a thermal imager, I have an FLIR One Pro LT I can lend you - I live in Bar Hill just outside Cambridge.

@robl

Thanks for all the info. I look to have just missed the thermal imaging season as next training is in November. It still feels cold enough to get a decent thermal imaging reading, though!

I'd not really thought about external wall insulation that much. The front elevation might be a bit troublesome as it is directly on the footpath; I'm guessing that the council would take a dim view of encroachment. The rear elevation is a bit more promising, although it faces east so will not get the predominant wind, and there also look to be some unresolved damp/salt marks which need fixing before then.

@majordennisbloodnok

I now have the solar panel group buy prices. The recommendation states it "is offering an average discount of 30%
compared to the typical market price for a similar high-quality solar PV system". 8 * 390W panels will cost £4,435, with 16 panels costing £7,365 (both include a £30/panel slate roof surcharge).

Battery storage (Fox ESS HV2600) is £3,030 for 4.7 kWh, £3,900 for 7 kWh and £4,650 for 9.4 kWh storage with a 10 year warranty; the group buy 0% VAT prices are about £400 or so above the 20% VAT inclusive prices in this link.

Overall I'm left a little uncertain about how good these prices are; I've asked for quotes from other suppliers, but I'm guessing that demand/inflation is taking hold of the renewables sector (having also been quoted around £12,000 to install an ~8kW ASHP, with extra to renew the radiator system).

@chickenbig The group buy for South Cambs has just offered me £3631 for 4.3 kWh storage, actual eqmt to be revealed - seems considerably higher than your offer.

@ChickenBig, we looked around at the component prices when we got our quote, and it didn't help us much. The comparison quotes from the various other companies was key, since all of them were coming in at about the same overall cost. Since the group buy overall price came in about the cost of a battery cheaper, it was clear what was the effect of the group discount. You're right that the cost of components may well have gone up with the extra demand, and you'll have to factor in whether you think there's any benefit in waiting to see if the prices will drop again. Either way, though, it still comes back round to getting those comparison quotes.

What I would say, though, is that there should be a webcast-style meeting where the chosen installer can introduce themselves and answer questions. If you find the same components cheaper than the group buy scheme, that's a perfect forum to bring this up and challenge Solar Together. My guess is that they'll be able to demonstrate that what they're buying is not quite what you found and that a like-for-like comparison is actually cheaper after all, and if that's right then happy days. However, you don't get to find out unless you ask, so I'd urge you to do so.

Your next step within the scheme after that, though, is getting the chosen installer round to provide a detailed survey and a more accurate quote based on what they calculate they can do rather than your "finger in the air" estimate of an appropriate number of panels and associated tech. That will be a cost, but you're only commiting to something like £150 or so. As a result, if after talking with the installer you don't feel comfortable continuing further then that £150 is all you lose.

@ronin92

Was the £3631 for installation alongside solar panels (i.e. the 0% VAT, plus cost benefits of having an all in one hybrid inverter), or stand-alone? I'm not sure what the price would be for me to get the no-solar system.

@chickenbig That's standalone.  I have panels already.

@ronin92

Aaah, so you'll be paying £600 because of a battery only installation is not 0% VAT rated. 😥 

@chickenbig If I were to just put on 4 panels ( I have roof space ) and an inverter, in addition to the batteries, would it become VAT-free?

Anyway, it's all moot.  The installers are so busy currently I can't even get quotes.  Nothing like energy prices to drive changes.

@ronin92 I don't see any restriction on the size of the solar system which must be installed to meet the 0% VAT criteria. The (now outdated) guidance does not mention batteries in section "2.14 Solar panels" (unlike wind and water turbines).

Still, I understand how difficult it is to get quotes for solar panels; I tried to contact about 10 installers and only 2 visited the site and only 1 (a non-MCS accredited installer) quoted. One installer said they were fully booked until August 2023! It is a good job I had the Solar Together group buy scheme to fall back on, although I harbour some doubts as to whether they will see this job as worth doing, being an older house with a more "characterful" skewed slate roof.

Well, the Solar Together scheme has let us down as we received a telephone call yesterday saying our roof was too complicated for them to do within the timescales. It is most disappointing took the installers nearly 3 1/2 months to figure that out. Most interestingly I asked the installer whether they could pass across the result of the roof survey, to which they said "They normally cost about £350. Because you are part of the Solar Together scheme and you're getting your deposit back we won't give you the roof survey." This being information of no use to them, I can't see why they would object to passing it on. I've complained to the Solar Together admin team who have promised to chase it up with the installer.

On the house improvement front, very little has improved (essentially just the double glazing). I'm also fully signed up to the Ripple wind farm (nearly 2,200W) so I am hoping this survives the price increases and higher interest rate environment. However I think the future is smokeless fuel burning as I've got a quote for installation within a week of asking, and are having someone around to do a survey today; that market does not seem to have overheated (yet). Now I just need to practice lugging 25kg bags of fuel around ...

@chickenbig, that’s very disappointing. Do you know if that’s Solar Together who let you down or the installer? If the latter, I hope you raise merry hell with Solar Together to stop that installer winning any more tenders.