S2D2

Ah okay, they must have put that value in as they applied for the grant. Good to know!

A good option if you have the skills. I don't, so for the time to learn and then do it, £2k seems a fair labour price. I do remember from the BUS form I had to sign that the quote has to be above £7.5k. So that puts a lower limit on costs, essentially making it a "your labour vs theirs" comparison.

PV + small Battery + fixed export + EV here, I'm with Cosy as I also export a hefty chunk of generation.

At a very high level: https://octopus.energy/press/project-mercury/

It may help to think that the BUS budget is a tiny fraction of the windfall tax on oil and gas companies? Provided it can get the cost down to the same as a combi swap buy-in will accelerate. Of course plenty of companies make up a number they think people will pay, that's why I've been shopping around for the last year. I reckon it would cost me £6k to DIY. I had a quote just to supply + replace radiators at £4k. Finally got a quote with the BUS grant for the whole lot for £2.2k, but that frankly just involved a heavy dose of lucky timing.

-20% but still, sounds like my quote a year ago. Keep rolling the dice on the random number generators...

I didn't get as far as getting them out for survey but sent my local heat geek elite the spec and the ballpark cost was £7k after the grant. Instead I made use of some Octopus promotional discounts and locked in a price of £2k. When I got a quote from Octopus a year ago it was £5.5k. Heat geek website has told me anywhere between £4k and £12k(!) after grant over time, it's essentially a random number generator. Worth checking Octopus with their current 20% off before the end of the month, comes out similar to what I ended up signing up to. Like you I wanted the perfect system but it would never make back that £5k.

Cosy has rapidly accelerated the payback period on my battery, three full cycles a day so saved the purchase of two additional modules. Sure, it's harder on the batteries, but you're getting the same savings just in a condensed time period. ~12p/kWh into a heat pump with a SCoP of around 4, just with a cheapish 2.8kWh battery. Definitely cheaper than the gas boiler.

Yes, it's definitely R290.

I've had mine nearly two years, copes absolutely fine in cold weather. A segment on the display went and appliances direct were very awkward about the "labour" component of the warranty as technically it needs servicing annually by an fgas engineer (despite not being fgas). They still sent out the part though.

I have 5.2kWp on a 3.68kW hybrid inverter because it can still divert PV to the battery even when capped at 3.68kW AC output. It does take some intelligent prediction to hold back the right amount of battery to make this work but there's no clipping as a result. All that said, I would have fitted a larger inverter if it wasn't so much hassle/cost with the DNO, the actual material cost difference is negligible.

I don't seem to be able to get lifestyle frustratingly, smets2 properties on the street are eligible but I've got a smets1 firmware upgraded to smets2 and it just doesn't show as available. Cosy is working well though, 12p/kWh average for me. Tomato would probably be cheaper.

Thanks for the explanation, unfortunately my solax battery is 102V. It's a very good price but I assume my inverter wouldn't be compatible which is a shame, solax batteries are twice the price! The tomato tariff looks interesting but the website errors out when I ask for a quote...

Which inverter are you using with those batteries? I'm on cosy with a small battery and can't make the sums add up to expand the battery storage with the official batteries.

I spotted it in this video as I'm about to have a Daikin installed myself: You're right that there are extra brackets to sit it in between the feet and the heatpump so it would be a pain if you don't have a flex connection that would accommodate the change. I'd be tempted by the gutter idea, quick and easy and it might just be enough. I really don't understand the design process of the drainage holes, I have a suitable drain nearby for a condensate pipe but there just doesn't appear to be a way to do this with the Daikins, unlike all other manufacturers, even my cheap A2A unit.