Energy savings
AlphaESS inverter joined to Octopus half-hourly meter reads and tariff prices.
Solar & battery installed by Heatable
£150 off solar £75 off a battery £50 off your Octopus bill referral
Year 2
7 Apr 2026 – 31 Aug 2026
Updated 31st August 2026, 01:30
waiting on Octopus meter
Total benefit
£1,287.17
A lower bill plus export payments, over 7009 half-hours
Saved on bills
£781.97
Against no solar and no battery
Earned from export
£505.20
Export payments — real money in
Would have paid
£952.07
No panels, no battery
Actually paid
£170.10
Before export payments and standing charge
· −£335.10 net of export
Solar generation
6,761 kWh
37.7% used at home,
4,210 kWh exported
Heating
1,030 kWh
£61.84 of the bill
· 29.1% of what the house used
· £302.25 without solar
Self-sufficiency
65.5%
3,540 kWh used, 1,220 kWh bought
EV charging
£128.27
1,021 kWh, excluded from savings
Battery round-trip
86.5%
1,479 kWh discharged
Where the benefit came from, by day
Solar and battery are separated by costing three worlds for every half hour — no panels and no battery, panels alone, then what actually happened — and taking the differences. A negative battery day is one that spent more storing energy than it gave back; it returns when the battery discharges. Export earnings sit inside the solar bar rather than beside it: the panels-alone world already sells its surplus, so that income is part of what solar is worth.
Solar (including export earnings)
Battery
View as table
| Day | Solar | Battery | Total | of which export | Solar kWh | Imported | Exported |
|---|---|---|---|---|---|---|---|
| Mon 31 Aug | £0.00 | £0.00 | £0.00 | £0.00 | 0.0 | 0.1 | 0.0 |
| Sun 30 Aug | £4.85 | −£0.74 | £4.10 | £1.38 | 30.1 | 0.8 | 11.5 |
| Sat 29 Aug | £2.36 | £0.36 | £2.73 | £0.17 | 12.3 | 1.1 | 1.4 |
| Fri 28 Aug | £5.95 | £0.28 | £6.23 | £3.79 | 40.1 | 1.3 | 31.6 |
| Thu 27 Aug | £4.32 | £0.21 | £4.52 | £2.22 | 28.1 | 1.3 | 18.5 |
| Wed 26 Aug | £6.81 | £0.14 | £6.95 | £3.58 | 43.8 | 1.0 | 29.8 |
| Tue 25 Aug | £7.18 | £0.46 | £7.64 | £4.55 | 50.4 | 1.0 | 37.9 |
| Mon 24 Aug | £7.79 | £0.36 | £8.15 | £3.76 | 47.2 | 1.7 | 31.3 |
| Sun 23 Aug | £7.55 | £0.89 | £8.44 | £2.70 | 41.2 | 1.6 | 22.5 |
| Sat 22 Aug | £7.50 | £0.29 | £7.79 | £3.93 | 47.2 | 2.0 | 32.7 |
| Fri 21 Aug | £6.59 | £0.60 | £7.19 | £3.36 | 41.5 | 1.5 | 28.0 |
| Thu 20 Aug | £6.33 | £0.11 | £6.43 | £2.82 | 38.5 | 1.3 | 23.5 |
| Wed 19 Aug | £4.85 | £0.65 | £5.50 | £2.23 | 31.6 | 1.1 | 18.5 |
| Tue 18 Aug | £4.48 | £0.51 | £4.98 | £1.72 | 27.0 | 0.8 | 14.3 |
| Mon 17 Aug | £5.86 | £0.31 | £6.17 | £2.54 | 36.5 | 0.7 | 21.2 |
| Sun 16 Aug | £5.45 | £0.49 | £5.93 | £1.87 | 32.1 | 0.8 | 15.6 |
| Sat 15 Aug | £6.26 | −£0.18 | £6.07 | £2.17 | 40.8 | 0.9 | 18.1 |
| Fri 14 Aug | £7.40 | −£0.47 | £6.93 | £3.55 | 48.8 | 0.8 | 29.6 |
| Thu 13 Aug | £8.27 | £1.41 | £9.67 | £3.97 | 52.0 | 0.6 | 33.1 |
| Wed 12 Aug | £7.84 | £0.21 | £8.06 | £4.39 | 53.9 | 0.7 | 36.6 |
| Tue 11 Aug | £7.90 | £0.28 | £8.18 | £5.06 | 55.8 | 0.8 | 42.2 |
| Mon 10 Aug | £8.32 | £0.14 | £8.47 | £4.32 | 54.4 | 1.0 | 36.0 |
| Sun 9 Aug | £6.86 | −£1.83 | £5.03 | £2.14 | 52.8 | 1.3 | 17.8 |
| Sat 8 Aug | £8.64 | £0.79 | £9.43 | £5.05 | 56.1 | 1.0 | 42.1 |
| Fri 7 Aug | £8.39 | −£0.19 | £8.20 | £5.41 | 58.3 | 1.0 | 45.1 |
| Thu 6 Aug | £8.32 | £0.67 | £8.99 | £4.28 | 49.3 | 1.3 | 35.7 |
| Wed 5 Aug | £6.50 | −£1.87 | £4.63 | £1.87 | 42.8 | 4.6 | 15.6 |
| Tue 4 Aug | £6.79 | £0.14 | £6.93 | £2.95 | 40.8 | 0.9 | 24.6 |
| Mon 3 Aug | £7.48 | £0.64 | £8.12 | £3.84 | 47.0 | 0.9 | 32.0 |
| Sun 2 Aug | £8.80 | £0.33 | £9.14 | £4.78 | 56.2 | 1.1 | 39.8 |
| Sat 1 Aug | £9.04 | £0.22 | £9.27 | £5.16 | 59.4 | 1.1 | 43.0 |
| Fri 31 Jul | £7.12 | £0.55 | £7.67 | £4.01 | 48.2 | 0.8 | 33.4 |
| Thu 30 Jul | £8.41 | £0.34 | £8.75 | £4.33 | 52.8 | 0.8 | 36.1 |
| Wed 29 Jul | £8.95 | £0.85 | £9.80 | £5.32 | 58.4 | 0.9 | 44.4 |
| Tue 28 Jul | £8.19 | −£0.35 | £7.84 | £3.99 | 51.9 | 1.3 | 33.3 |
| Mon 27 Jul | £8.23 | £1.81 | £10.04 | £5.19 | 57.5 | 1.1 | 43.2 |
| Sun 26 Jul | £7.54 | £0.01 | £7.55 | £2.57 | 43.4 | 1.0 | 21.4 |
| Sat 25 Jul | £9.35 | £1.59 | £10.94 | £5.15 | 59.8 | 1.2 | 42.9 |
| Fri 24 Jul | £7.81 | −£0.56 | £7.25 | £2.68 | 44.9 | 1.5 | 22.3 |
| Thu 23 Jul | £6.33 | £0.91 | £7.24 | £2.93 | 40.5 | 1.8 | 24.4 |
| Wed 22 Jul | £6.53 | £0.55 | £7.08 | £2.60 | 41.0 | 1.4 | 21.6 |
| Tue 21 Jul | £6.08 | £1.93 | £8.01 | £2.67 | 36.9 | 1.7 | 22.2 |
| Mon 20 Jul | £10.04 | £0.71 | £10.76 | £5.46 | 64.3 | 2.0 | 45.5 |
| Sun 19 Jul | £9.07 | £0.72 | £9.79 | £5.99 | 62.9 | 1.4 | 49.9 |
| Sat 18 Jul | £8.79 | −£0.22 | £8.57 | £5.67 | 61.4 | 1.0 | 47.3 |
| Fri 17 Jul | £8.00 | £0.09 | £8.09 | £5.09 | 55.5 | 1.4 | 42.5 |
| Thu 16 Jul | £9.58 | −£0.24 | £9.34 | £5.30 | 64.7 | 0.9 | 44.2 |
| Wed 15 Jul | £9.76 | £1.20 | £10.96 | £5.54 | 66.0 | 1.2 | 46.1 |
| Tue 14 Jul | £11.88 | −£0.12 | £11.77 | £5.20 | 67.1 | 0.9 | 43.3 |
| Mon 13 Jul | £9.62 | −£0.52 | £9.10 | £5.43 | 67.4 | 1.0 | 45.3 |
| Sun 12 Jul | £9.19 | −£0.66 | £8.53 | £5.44 | 68.3 | 0.9 | 45.3 |
| Sat 11 Jul | £9.56 | £0.39 | £9.95 | £6.14 | 66.7 | 0.8 | 51.2 |
| Fri 10 Jul | £9.40 | £0.78 | £10.18 | £5.83 | 62.9 | 0.8 | 48.6 |
| Thu 9 Jul | £9.28 | £0.19 | £9.47 | £5.94 | 63.6 | 0.8 | 49.5 |
| Wed 8 Jul | £10.20 | £0.42 | £10.63 | £5.22 | 63.5 | 0.7 | 43.5 |
| Tue 7 Jul | £9.02 | £0.51 | £9.53 | £5.70 | 62.3 | 0.9 | 47.5 |
| Mon 6 Jul | £9.73 | £0.57 | £10.30 | £5.77 | 64.5 | 0.9 | 48.1 |
| Sun 5 Jul | £10.40 | £0.23 | £10.64 | £5.17 | 63.1 | 1.1 | 43.1 |
| Sat 4 Jul | £9.72 | £0.49 | £10.21 | £4.50 | 57.2 | 1.2 | 37.5 |
| Fri 3 Jul | £10.08 | −£0.07 | £10.01 | £6.48 | 68.5 | 1.1 | 54.0 |
| Thu 2 Jul | £9.40 | −£0.01 | £9.38 | £5.58 | 62.2 | 0.9 | 46.5 |
| Wed 1 Jul | £7.17 | −£1.03 | £6.14 | £2.29 | 43.4 | 1.8 | 19.1 |
| Tue 30 Jun | £6.54 | −£1.30 | £5.24 | £2.23 | 41.5 | 1.6 | 18.6 |
| Mon 29 Jun | £9.71 | £0.16 | £9.88 | £5.53 | 62.4 | 0.9 | 46.1 |
| Sun 28 Jun | £9.94 | £0.27 | £10.21 | £4.47 | 59.6 | 0.8 | 37.3 |
| Sat 27 Jun | £7.15 | £0.37 | £7.51 | £3.47 | 45.0 | 0.8 | 28.9 |
| Fri 26 Jun | £9.37 | −£1.65 | £7.72 | £3.44 | 60.0 | 0.6 | 28.6 |
| Thu 25 Jun | £9.90 | −£1.67 | £8.23 | £4.36 | 66.3 | 0.8 | 36.3 |
| Wed 24 Jun | £9.93 | £0.50 | £10.43 | £6.11 | 66.4 | 0.5 | 50.9 |
| Tue 23 Jun | £7.93 | £0.23 | £8.15 | £5.15 | 55.6 | 0.7 | 42.9 |
| Mon 22 Jun | £10.04 | £0.05 | £10.09 | £6.26 | 67.6 | 1.2 | 52.1 |
| Sun 21 Jun | £8.16 | £0.38 | £8.55 | £5.06 | 53.5 | 1.1 | 42.1 |
| Sat 20 Jun | £6.06 | −£0.38 | £5.68 | £2.62 | 36.9 | 1.4 | 21.9 |
| Fri 19 Jun | £10.45 | £0.46 | £10.91 | £6.30 | 70.3 | 1.8 | 52.5 |
| Thu 18 Jun | £6.07 | £0.28 | £6.35 | £2.51 | 34.6 | 1.7 | 21.0 |
| Wed 17 Jun | £6.46 | £0.15 | £6.61 | £2.94 | 39.2 | 1.8 | 24.5 |
| Tue 16 Jun | £9.60 | £0.02 | £9.61 | £5.73 | 63.2 | 1.9 | 47.7 |
| Mon 15 Jun | £9.42 | −£0.16 | £9.26 | £4.37 | 55.8 | 2.2 | 36.4 |
| Sun 14 Jun | £10.85 | −£0.60 | £10.25 | £4.82 | 67.0 | 2.0 | 40.1 |
| Sat 13 Jun | £12.78 | £1.86 | £14.64 | £5.00 | 72.0 | 2.8 | 41.6 |
| Fri 12 Jun | £8.61 | £1.53 | £10.14 | £1.99 | 35.3 | 16.0 | 16.6 |
| Thu 11 Jun | £5.68 | £1.74 | £7.42 | £0.69 | 18.0 | 17.3 | 5.7 |
| Wed 10 Jun | £0.00 | −£0.06 | −£0.06 | £0.00 | 0.0 | 22.4 | 0.0 |
| Tue 9 Jun | £2.08 | −£0.05 | £2.03 | £0.17 | 6.8 | 25.3 | 1.5 |
| Mon 8 Jun | £5.59 | £0.94 | £6.54 | £1.30 | 23.5 | 16.3 | 10.9 |
| Sun 7 Jun | £6.68 | −£2.18 | £4.50 | £0.91 | 34.8 | 10.4 | 7.6 |
| Sat 6 Jun | £4.79 | £3.69 | £8.48 | £0.48 | 19.4 | 5.1 | 4.0 |
| Fri 5 Jun | £7.16 | −£0.42 | £6.74 | £2.85 | 40.7 | 4.2 | 23.7 |
| Thu 4 Jun | £7.91 | £0.55 | £8.46 | £2.10 | 40.1 | 3.9 | 17.5 |
| Wed 3 Jun | £5.39 | £0.08 | £5.47 | £0.39 | 20.8 | 4.7 | 3.3 |
| Tue 2 Jun | £5.96 | £0.28 | £6.24 | £1.94 | 31.2 | 2.1 | 16.2 |
| Mon 1 Jun | £7.63 | −£0.11 | £7.52 | £4.01 | 48.7 | 1.5 | 33.5 |
| Sun 31 May | £7.17 | £0.10 | £7.27 | £3.80 | 46.8 | 0.9 | 31.7 |
| Sat 30 May | £9.24 | £0.34 | £9.57 | £5.35 | 60.3 | 1.0 | 44.6 |
| Fri 29 May | £7.53 | £0.31 | £7.84 | £3.72 | 46.1 | 0.7 | 31.0 |
| Thu 28 May | £8.04 | −£0.07 | £7.97 | £4.84 | 55.8 | 0.8 | 40.3 |
| Wed 27 May | £10.57 | £0.72 | £11.28 | £5.61 | 65.5 | 0.8 | 46.8 |
| Tue 26 May | £9.56 | £0.42 | £9.98 | £6.02 | 64.1 | 0.9 | 50.2 |
| Mon 25 May | £8.85 | −£0.09 | £8.76 | £5.20 | 59.5 | 0.8 | 43.4 |
| Sun 24 May | £8.94 | £0.32 | £9.26 | £5.52 | 60.6 | 1.0 | 46.0 |
| Sat 23 May | £9.85 | £0.05 | £9.90 | £4.73 | 61.0 | 1.1 | 39.5 |
| Fri 22 May | £10.44 | £1.39 | £11.83 | £6.12 | 65.1 | 7.0 | 51.0 |
| Thu 21 May | £11.32 | £1.54 | £12.85 | £4.62 | 58.0 | 15.7 | 38.5 |
| Wed 20 May | £9.46 | £1.31 | £10.76 | £2.30 | 39.9 | 21.5 | 19.1 |
| Tue 19 May | £6.95 | £3.55 | £10.50 | £0.70 | 27.6 | 23.9 | 5.9 |
| Mon 18 May | £8.92 | £3.05 | £11.97 | £1.42 | 34.5 | 22.7 | 11.8 |
| Sun 17 May | £11.41 | £3.20 | £14.60 | £2.39 | 46.4 | 21.8 | 19.9 |
| Sat 16 May | £9.21 | £2.94 | £12.15 | £1.39 | 35.6 | 21.9 | 11.6 |
| Fri 15 May | £9.37 | £2.98 | £12.35 | £1.98 | 39.7 | 21.7 | 16.5 |
| Thu 14 May | £10.36 | £2.25 | £12.60 | £2.93 | 45.8 | 24.3 | 24.4 |
| Wed 13 May | £9.20 | £3.50 | £12.70 | £2.76 | 43.6 | 20.0 | 23.0 |
| Tue 12 May | £10.29 | £2.63 | £12.92 | £2.76 | 49.2 | 22.6 | 23.0 |
| Mon 11 May | £7.34 | £3.07 | £10.41 | £0.80 | 29.3 | 25.2 | 6.7 |
| Sun 10 May | £5.34 | £3.68 | £9.02 | £0.71 | 19.4 | 18.0 | 5.9 |
| Sat 9 May | £10.66 | £2.00 | £12.66 | £4.32 | 56.0 | 15.7 | 36.0 |
| Fri 8 May | £9.25 | £2.01 | £11.26 | £2.84 | 44.0 | 17.0 | 23.7 |
| Thu 7 May | £6.91 | £1.99 | £8.90 | £0.60 | 24.2 | 17.5 | 5.0 |
| Wed 6 May | £9.42 | £1.50 | £10.92 | £3.09 | 44.9 | 15.5 | 25.7 |
| Tue 5 May | £9.67 | £1.54 | £11.21 | £4.38 | 53.0 | 15.2 | 36.5 |
| Mon 4 May | £6.48 | £1.30 | £7.78 | £1.37 | 27.2 | 20.7 | 11.5 |
| Sun 3 May | £8.69 | £2.19 | £10.88 | £3.32 | 42.7 | 13.9 | 27.7 |
| Sat 2 May | £8.91 | £0.89 | £9.80 | £4.66 | 52.2 | 12.0 | 38.8 |
| Fri 1 May | £8.57 | £0.73 | £9.30 | £4.45 | 50.4 | 14.6 | 37.1 |
| Thu 30 Apr | £9.72 | £2.80 | £12.52 | £4.08 | 53.5 | 18.0 | 34.0 |
| Wed 29 Apr | £9.20 | £2.25 | £11.45 | £4.42 | 55.2 | 14.5 | 36.9 |
| Tue 28 Apr | £7.75 | £1.50 | £9.25 | £3.05 | 43.3 | 15.9 | 25.5 |
| Mon 27 Apr | £8.83 | £1.99 | £10.83 | £4.09 | 53.9 | 15.6 | 34.0 |
| Sun 26 Apr | £9.71 | £0.97 | £10.68 | £3.59 | 53.0 | 16.7 | 29.9 |
| Sat 25 Apr | £9.38 | £2.22 | £11.60 | £3.55 | 52.3 | 19.9 | 29.6 |
| Fri 24 Apr | £10.15 | £2.31 | £12.46 | £4.40 | 59.8 | 22.2 | 36.7 |
| Thu 23 Apr | £9.59 | £3.60 | £13.19 | £4.15 | 57.3 | 19.6 | 34.6 |
| Wed 22 Apr | £10.02 | £2.67 | £12.70 | £4.20 | 59.3 | 24.3 | 35.0 |
| Tue 21 Apr | £7.55 | £2.91 | £10.47 | £1.01 | 36.2 | 23.1 | 8.4 |
| Mon 20 Apr | £7.82 | £3.03 | £10.85 | £2.37 | 40.9 | 20.1 | 19.7 |
| Sun 19 Apr | £9.31 | £2.14 | £11.45 | £3.44 | 51.6 | 17.3 | 28.7 |
| Sat 18 Apr | £8.78 | £1.63 | £10.42 | £2.81 | 46.5 | 19.8 | 23.4 |
| Fri 17 Apr | £8.85 | £1.51 | £10.36 | £3.25 | 48.6 | 22.0 | 27.0 |
| Thu 16 Apr | £6.03 | £2.08 | £8.11 | £0.57 | 23.9 | 31.5 | 4.8 |
| Wed 15 Apr | £3.72 | £3.52 | £7.24 | £0.59 | 13.3 | 36.5 | 4.9 |
| Tue 14 Apr | £5.32 | £3.30 | £8.62 | £0.63 | 19.2 | 34.5 | 5.3 |
| Mon 13 Apr | £4.85 | £3.11 | £7.97 | £0.67 | 17.4 | 32.4 | 5.5 |
| Sun 12 Apr | £5.04 | £3.22 | £8.25 | £0.77 | 18.2 | 32.3 | 6.4 |
| Sat 11 Apr | £4.16 | £3.50 | £7.66 | £0.65 | 14.9 | 31.5 | 5.4 |
| Fri 10 Apr | £4.23 | £2.35 | £6.58 | £0.59 | 15.2 | 25.0 | 4.9 |
| Thu 9 Apr | £2.79 | £2.10 | £4.89 | £0.48 | 10.4 | 24.2 | 4.0 |
| Wed 8 Apr | £3.01 | £1.63 | £4.65 | £0.49 | 11.0 | 30.6 | 4.1 |
| Tue 7 Apr | £4.05 | £3.50 | £7.55 | £0.68 | 14.5 | 31.4 | 5.6 |
Cumulative benefit
Running total across the selected window.
Friday 12 June 2026, half by half
Energy arriving above the line, energy leaving below it, and the price you were paying on the same timeline. Charging through a cheap window and discharging through an expensive one is the shape to look for.
Solar generated
Imported
Exported (below the line)
Inverter versus meter
The two measure at different points in the circuit and will never agree exactly. A few percent of drift is normal; a consistent double-digit gap means one feed is wrong and the solar/battery split should be treated with suspicion. The headline figures come from the meter either way.
| Day | Meter import | Inverter import | Drift | Meter export | Inverter export | Drift |
|---|---|---|---|---|---|---|
| Mon 31 Aug | 0.06 | 0.00 | -100.0% | 0.00 | 0.00 | — |
| Sun 30 Aug | 0.84 | 0.60 | -28.5% | 11.50 | 18.30 | 59.1% |
| Sat 29 Aug | 1.11 | 0.92 | -16.8% | 1.41 | 2.61 | 85.4% |
| Fri 28 Aug | 1.34 | 0.98 | -26.8% | 31.59 | 31.49 | -0.3% |
| Thu 27 Aug | 1.26 | 0.94 | -25.6% | 18.50 | 18.42 | -0.4% |
| Wed 26 Aug | 1.03 | 0.78 | -24.0% | 29.84 | 29.77 | -0.2% |
| Tue 25 Aug | 1.04 | 0.69 | -33.3% | 37.91 | 37.78 | -0.3% |
| Mon 24 Aug | 1.67 | 1.05 | -37.1% | 31.32 | 30.89 | -1.4% |
| Sun 23 Aug | 1.60 | 0.98 | -38.9% | 22.49 | 22.12 | -1.6% |
| Sat 22 Aug | 1.96 | 1.26 | -35.8% | 32.72 | 32.24 | -1.5% |
| Fri 21 Aug | 1.50 | 0.92 | -38.8% | 28.02 | 27.66 | -1.3% |
| Thu 20 Aug | 1.28 | 0.76 | -40.8% | 23.51 | 23.23 | -1.2% |
| Wed 19 Aug | 1.10 | 0.65 | -41.0% | 18.55 | 18.42 | -0.7% |
| Tue 18 Aug | 0.77 | 0.48 | -37.5% | 14.32 | 14.22 | -0.7% |
Return on investment
Measured across everything on record (7 Apr 2025 to 31 Aug 2026), not the range selected above — annualising a fortnight of summer would roughly double the apparent return. The yearly figure comes from the trailing twelve months, so it covers a full seasonal cycle.
Recovered so far
£4,118
of £18,990
21.7% recovered
£14,872 to go
Benefit per year
£2,743
Trailing 12 months
Annual return
14.4%
Of the £18,990 outlay
Full payback
5.4 yrs
Around Feb 2032