Cost, Energy & Comfort [6 Days | 31 Jul–5 Aug 26] HP £2.11 cheaper than modeled boiler without off-grid solar+battery DHW HP — IGo EV Saver - £0.90 use + £2.80 elec SC = £3.70 Boiler — Fixed gas + Agile elec - £1.05 gas + £1.76 gas SC + £3.00 elec SC = £5.80

Solar hot water: [123 Days | 5 Apr 26 to 5 Aug 26] 5 Aug: 2.30 kWh; since 5 Apr 277.2 kWh into tank. Modeled boiler gas input ~402.0 kWh; net input saved ~124.7 kWh. Modeled CO₂e avoided: ~0.65 kg on 5 Aug; ~78.8 kg since 5 Apr. ~31% less input, ~1.45x vs boiler model.

Solar payback: [123 Days | 5 Apr 26 to 5 Aug 26] Today 5.04 kWh; import saved £0.98 + export earned £0.10 Rates 23.9p Tracker import; 12.0p export Total 1011.20 kWh; £194.50 total return (£1.58/day) Payback £595.92 left; 24.6% recovered; break-even 18 Oct 2027

Cost, Energy & Comfort [3 Days | 2 Aug–4 Aug 26] HP £1.01 cheaper than modeled boiler without off-grid solar+battery DHW HP — IGo EV Saver - £0.41 use + £1.40 elec SC = £1.81 Boiler — Fixed gas + Agile elec - £0.44 gas + £0.88 gas SC + £1.50 elec SC = £2.82

Solar payback: [122 Days | 5 Apr 26 to 4 Aug 26] Today 6.33 kWh; import saved £0.64 + export earned £0.45 Rates 29.7p Tracker import; 12.0p export Total 1006.16 kWh; £193.43 total return (£1.59/day) Payback £596.99 left; 24.5% recovered; break-even 17 Oct 2027

Cost, Energy & Comfort [832 Days | 24 Apr 24–3 Aug 26] Modeled boiler without off-grid solar+battery DHW £118.87 cheaper than HP HP — Agile - £1811.21 use + £414.48 elec SC = £2225.69 Boiler — Tracker→Fixed gas + Tracker→Agile elec - £1328.32 gas + £238.78 gas SC + £539.71 elec SC = £2106.82

Solar hot water: [121 Days | 5 Apr 26 to 3 Aug 26] 3 Aug: 2.27 kWh; since 5 Apr 274.9 kWh into tank. Modeled boiler gas input ~398.6 kWh; net input saved ~123.7 kWh. Modeled CO₂e avoided: ~0.65 kg on 3 Aug; ~78.1 kg since 5 Apr. ~31% less input, ~1.45x vs boiler model.

Solar payback: [121 Days | 5 Apr 26 to 3 Aug 26] Today 7.65 kWh; import saved £1.01 + export earned £0.46 Rates 29.5p Tracker import; 12.0p export Total 999.83 kWh; £192.33 total return (£1.59/day) Payback £598.09 left; 24.3% recovered; break-even 15 Oct 2027

Cost, Energy & Comfort [365 Days | 3 Aug 25–2 Aug 26] HP £283.30 cheaper than modeled boiler without off-grid solar+battery DHW HP — Agile - £437.90 use + £182.44 elec SC = £620.34 Boiler — Tracker→Fixed gas + Tracker→Agile elec - £559.32 gas + £108.57 gas SC + £235.75 elec SC = £903.64

Solar hot water: [120 Days | 5 Apr 26 to 2 Aug 26] 2 Aug: 2.31 kWh; since 5 Apr 272.7 kWh into tank. Modeled boiler gas input ~395.3 kWh; net input saved ~122.7 kWh. Modeled CO₂e avoided: ~0.66 kg on 2 Aug; ~77.5 kg since 5 Apr. ~31% less input, ~1.45x vs boiler model.

Solar payback: [120 Days | 5 Apr 26 to 2 Aug 26] Today 6.87 kWh; import saved £0.62 + export earned £0.52 Rates 29.6p Tracker import; 12.0p export Total 992.17 kWh; £190.87 total return (£1.59/day) Payback £599.55 left; 24.1% recovered; break-even 15 Oct 2027

This heat pump increased total energy demand by 74.7%, from 13,835.8 kWh to 24,177.6 kWh a year. Still net positive on many other levels 💚☺️

Your Gas Boiler Has a DIRTY Secret... But Is My Heat Pump Better?

YouTube video by Everything Home

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Cost, Energy & Comfort [180 Days | 3 Feb–1 Aug 26] HP £125.02 cheaper than modeled boiler without off-grid solar+battery DHW HP — Agile - £177.17 use + £89.97 elec SC = £267.14 Boiler — Tracker→Fixed gas + Tracker→Agile elec - £224.71 gas + £53.33 gas SC + £114.11 elec SC = £392.15

Solar hot water: [119 Days | 5 Apr 26 to 1 Aug 26] 1 Aug: 3.50 kWh; since 5 Apr 270.3 kWh into tank. Modeled boiler gas input ~392.0 kWh; net input saved ~121.7 kWh. Modeled CO₂e avoided: ~1.00 kg on 1 Aug; ~76.8 kg since 5 Apr. ~31% less input, ~1.45x vs boiler model.

Solar payback: [119 Days | 5 Apr 26 to 1 Aug 26] Today 10.43 kWh; import saved £0.50 + export earned £0.96 Rates 26.8p Tracker import; 12.0p export Total 985.30 kWh; £189.73 total return (£1.59/day) Payback £600.69 left; 24.0% recovered; break-even 13 Oct 2027

[31 Days | 1 Jul–31 Jul 26] Profile-based subtotal: HP £13.22 lower vs modeled boiler without off-grid solar+battery DHW HP IGo EV: £4.21 use + £14.46 elec SC = £18.67 Boiler gas Fixed, elec Agile: £7.30 gas + £9.10 gas SC + £15.49 elec SC = £31.89

Solar hot water: [118 Days | 5 Apr 26 to 31 Jul 26] 31 Jul: 0.46 kWh; since 5 Apr 266.8 kWh into tank. Modeled boiler gas input ~386.9 kWh; net input saved ~120.1 kWh. Modeled CO₂e avoided: ~0.13 kg on 31 Jul; ~75.8 kg since 5 Apr. ~31% less input, ~1.45x vs boiler model.

Solar payback: [118 Days | 5 Apr 26 to 31 Jul 26] Today 9.17 kWh; import saved £0.72 + export earned £0.76 Rates 29.9p Tracker import; 12.0p export Total 974.87 kWh; £188.27 total return (£1.60/day) Payback £602.15 left; 23.8% recovered; break-even 12 Oct 2027

1/4 Starting tomorrow... A fairer heat pump vs boiler comparison should use the total household bill, including unavoidable standing charges. e.g. Over this 90-day period, the heat pump household cost £65.99, compared with £101.77 for the modelled boiler household.

Cost, Energy & Comfort [90 Days | 2 May 26 to 30 Jul 26] HP £20.99 cheaper than boiler without off-grid solar+battery DHW HP — IGo EV Saver - £39.52 SC-adjusted - £65.98 elec+SC - £26.47 avoided gas SC Boiler — Tracker -> Fixed, modeled - £60.51 incl gas SC

Solar hot water: [117 Days | 5 Apr 26 to 30 Jul 26] 30 Jul: 2.31 kWh; since 5 Apr 266.4 kWh into tank. Modeled boiler gas input ~386.2 kWh; net input saved ~119.9 kWh. Modeled CO₂e avoided: ~0.66 kg on 30 Jul; ~75.7 kg since 5 Apr. ~31% less input, ~1.45x vs boiler model.

Solar payback: [117 Days | 5 Apr 26 to 30 Jul 26] Today 11.80 kWh; import saved £1.08 + export earned £0.91 Rates 29.2p Tracker import; 12.0p export Total 965.70 kWh; £186.79 total return (£1.60/day) Payback £603.63 left; 23.6% recovered; break-even 11 Oct 2027

Cost, Energy & Comfort [30 Days | 30 Jun 26 to 29 Jul 26] HP £6.93 cheaper than boiler without off-grid solar+battery DHW HP — IGo EV Saver - £9.24 SC-adjusted - £18.05 elec+SC - £8.80 avoided gas SC Boiler — Fixed, modeled - £16.17 incl gas SC

Solar hot water: [116 Days | 5 Apr 26 to 29 Jul 26] 29 Jul: 1.47 kWh; since 5 Apr 264.1 kWh into tank. Modeled boiler gas input ~382.9 kWh; net input saved ~118.8 kWh. Modeled CO₂e avoided: ~0.42 kg on 29 Jul; ~75.0 kg since 5 Apr. ~31% less input, ~1.45x vs boiler model.

Solar payback: [116 Days | 5 Apr 26 to 29 Jul 26] Today 6.69 kWh; import saved £0.92 + export earned £0.37 Rates 29.3p Tracker import; 12.0p export Total 953.91 kWh; £184.80 total return (£1.59/day) Payback £605.62 left; 23.4% recovered; break-even 11 Oct 2027

Cost, Energy & Comfort [21 Days | 8 Jul 26 to 28 Jul 26] HP £5.21 cheaper than boiler without off-grid solar+battery DHW HP — IGo EV Saver - £6.34 SC-adjusted - £12.50 elec+SC - £6.16 avoided gas SC Boiler — Fixed, modeled - £11.55 incl gas SC

Solar hot water: [115 Days | 5 Apr 26 to 28 Jul 26] 28 Jul: 1.68 kWh; since 5 Apr 262.6 kWh into tank. Modeled boiler gas input ~380.8 kWh; net input saved ~118.2 kWh. Modeled CO₂e avoided: ~0.48 kg on 28 Jul; ~74.6 kg since 5 Apr. ~31% less input, ~1.45x vs boiler model.

Solar payback: [115 Days | 5 Apr 26 to 28 Jul 26] Today 7.12 kWh; import saved £0.46 + export earned £0.60 Rates 28.3p Tracker import; 12.0p export Total 947.22 kWh; £183.51 total return (£1.60/day) Payback £606.91 left; 23.2% recovered; break-even 9 Oct 2027

Cost, Energy & Comfort [18 Days | 10 Jul 26 to 27 Jul 26] HP £4.26 cheaper than boiler without off-grid solar+battery DHW HP — IGo EV Saver - £5.47 SC-adjusted - £10.75 elec+SC - £5.28 avoided gas SC Boiler — Fixed, modeled - £9.73 incl gas SC

Solar payback: [114 Days | 5 Apr 26 to 27 Jul 26] Today 5.36 kWh; import saved £0.74 + export earned £0.28 Rates 28.3p Tracker import; 12.0p export Total 940.09 kWh; £182.46 total return (£1.60/day) Payback £607.96 left; 23.1% recovered; break-even 7 Oct 2027