Hey everyone,
It’s been a whirlwind since the Daikin heat pump went live in October 2025 – ditching the old gas boiler for good and completing our multi-year journey to an all-electric, ultra-efficient home. With full 2024 solar data, early heat pump stats, and our Intelligent Octopus Go tariff humming along at 99.5% off-peak, I thought it was time for a proper update: what are the real savings, and what’s the ROI looking like?
Quick Recap of the Setup
- Solar: 4.5 kWp installed mid-2021 (£12k total incl. 16.8 kWh GivEnergy batteries + charger)
- Heat pump: Daikin 8 kW (net £5,242 after grant) – keeping the house at a steady 20°C
- EVs: 2021 Hyundai Kona (£15k, ~8,000 miles/year) + 2021 Tesla Model 3 (£19k, ~11,000 miles/year)
- Magic sauce: Home Assistant automations shifting everything to 7p/kWh off-peak windows
The Numbers – Where We Are Now 2024 solar: 3,200 kWh generated, 1,851 kWh exported (great export credit at 15p/kWh). With the heat pump adding winter load, self-consumption should climb nicely – batteries are loving it.
Projected full-year usage post-heat pump:
- House basics: ~4,000 kWh
- Heat pump: ~3,574 kWh (early data shows COP 4.0 over first 7 weeks – 2,080 kWh heat from just 520 kWh input!)
- EVs: ~5,107 kWh (Kona averaging 3.9 mi/kWh, Model 3 3.6 mi/kWh) Total: ~12,681 kWh gross → ~10,761 kWh imported after solar.
Current bill: ~£769/year (mostly 7p off-peak, tiny peak usage, minus export). Compare that to before: £4,853/year (gas £947 + elec £1,219 + petrol/diesel £2,687 for equivalent miles in the BMW X3 / VW Up).
Savings & ROI – The Bottom Line Annual savings: ~£4,084 (conservative – could edge closer to my original blog prediction of £4,500–£5,200 if self-consumption improves or winters stay mild).
Total investment: £17,242 → payback in about 4.2 years, with an effective annual ROI of ~23.7%. That’s beating most investments hands-down, and we’re only a few months into the heat pump era!
The house feels warmer and quieter, bills are predictable and tiny, driving is basically free at night, and we’re slashing carbon. Early days, but so far, so brilliant.
What do you think? Anyone else gone full heat pump + solar + batteries? Drop your stats in the comments – always keen to compare notes.
Thanks for reading.