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That's really interesting. This bit confused me as to how you're meant to apply if you're getting a whole house refurbed including insulation and an ASHP in place of a gas boiler:
"Your property must have a valid Energy Performance Certificate (EPC) with no outstanding recommendations for loft or cavity wall insulation."
https://www.gov.uk/apply-boiler-upgrade-scheme/check-if-youre-eligible
...but you're still applying for the grant despite getting everything done at once?
I'm not thinking that PV would heat the house under all circumstances. I think we'd have to rely on a combi boiler a bit, but we could substantially reduce our use of it from the PVs. What I'm struggling to understand is what an electric wet-UFH system looks like. Where does the element go? Is there a buffer tank and an expansion vessel? How big are they?
ffm-
If by ‘electric’ you mean ASHP, then it’s exactly the same as a ‘system’ boiler, with a hot water tank, pump, buffer/volumiser as necessary, rads, wet UFH etc, with the only difference being that you have an outdoor monoblock heat pump unit heating the water being pumped instead of an indoor gas boiler. The only direct electric resistance ‘element’ in the system might be a backup immersion heater for the hot water cylinder, but this isn’t essential.
The flow temperatures should ideally be lower with ASHP, therefore any rads should be larger.
As for the EPC requirement, you can check if your house has one on the gov.uk website, most do. If it doesn’t, obtaining one isn’t hard or expensive.
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Basically if the installer states that any loft insulation etc is getting done at the same time it’s fine. BUS will probably ask them for a photo or other proof.
ectoplasmosis
dbr
We’re currently claiming the full £7.5K BUS grant for installing ASHP as part of an ongoing refurb/extension; just find a friendly independent MCS-certified installer and it’s not a problem.
Solar on its own for heating won’t work (unless you have a field you can cover with PV panels). Most efficient system is solar PV charging a battery and running ASHP to ‘charge’ a thick, well-insulated UFH slab during off-peak periods of a smart energy tariff, then running your house from the battery and exporting solar at a high rate during the day.
Initial outlay for such a setup is very high, and payback often long enough to make it not worthwhile if your only criteria is reducing energy bills.
Sack off the gas if you can afford to.