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
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.
View as table
| Day | Solar | Battery | Total | of which export | Solar kWh | Imported | Exported |
|---|---|---|---|---|---|---|---|
| Tue 1 Sep | £0.00 | £0.00 | £0.00 | £0.00 | 0.0 | 0.1 | 0.0 |
Cumulative benefit
Running total across the selected window.
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 |
|---|---|---|---|---|---|---|
| Tue 1 Sep | 0.06 | 0.72 | 1,100.0% | 0.00 | 29.54 | — |
Return on investment
Measured across everything on record (7 Apr 2025 to 1 Sep 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.