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Batteries · Advice

Can I make money selling battery power to the grid?

Short answer

Only on wide spreads. Buying at 8p and selling at 12p with a 90% round trip earns 3.1p per kWh, less than the battery wear of about 16–25p per kWh. Octopus Flux (15.3p night import, 28.6p 4–7pm export) earns about 11.6p before wear. Using the stored power at home instead of paying ~30p peak saves about 21p per kWh.

Last checked 24 September 2026 · 14 sources

What should I know before deciding?

Margin per kWh exported = sell price − buy price ÷ RTE. 8p → 12p at 90%: 12 − 8.89 = 3.1p. At 150 kWh a day that's £4.67/day maximum (one full cycle), before wear. £20/day on 150 kWh needs a 13.3p net margin per kWh, e.g. buy 8p and sell ≥22.2p. Export is capped by the DNO limit × window length: 5 kW × 3 h (16:00-19:00) = 15 kWh per day, however big the battery. Agile 12-month (London): cheapest 4 h/day 12.39p in; Agile Outgoing 16-19 mean 17.95p out → 4.2p margin at 90%.

Can a big battery really earn GBP20 a day trading electricity?

Not on an 8p-in, 12p-out spread. Allowing for 10% losses, each kWh nets about 3p, so 135 kWh delivered earns roughly £4 a day. Earning £20 needs peak export prices near 30p, three-phase inverters, a DNO export permission large enough to sell over 100 kWh in the evening peak, and a warranty that tolerates the throughput.

8p buy / 12p sell: 12 - 8/0.9 = 3.1p per kWh; 150 kWh x 90% = 135 kWh -> ~£4.20/day. Flux-style peak export ~28-29p vs Flux cheap import ~15.3p: ~11.6p/kWh net -> £20 needs ~170 kWh exported in 16:00-19:00, i.e. ~57 kW of export permission for 3 hours. Agile Outgoing occasionally spikes higher; averages are what matter.

Can I get paid for letting the grid use my battery?

Yes, through virtual power plants and flexibility schemes that discharge or charge your battery during grid events. Examples in 2026 include Axle Energy (about £1 per kWh in events with a £10 monthly minimum, owner reports), Tesla's Powerwall VPP with Octopus, Octopus Saving Sessions and Power-ups, and NESO's Demand Flexibility Service via suppliers and apps.

Axle: independent platform working alongside your supplier; supports brands incl. Fox ESS, GivEnergy, SigEnergy, SolaX, Solis, Duracell, SolarEdge (site logos); owner blog Feb 2026: £1/kWh, £10/month minimum, ~20 h notice. Tesla/Octopus Powerwall VPP launched July 2025 (secondary); Tesla Energy Ventures got a GB supply licence effective 11 Mar 2026; a Tesla Electric UK retail launch date was not confirmed in sources read. NESO DFS: year-round since Nov 2024; v4 from 9 Apr 2026 adds bi-directional flexibility and zonal procurement; from 7 Oct 2026 constraint management.

How does a DNO export limit affect what my battery can earn?

An export limit caps how much the battery can sell in a peak window, whatever its size. At the G98 3.68 kW limit a battery can export at most about 11 kWh between 4pm and 7pm, or about 15 kWh at 5 kW. Anything larger only earns by covering your own evening use or by exporting at lower off-peak rates.

Max peak-window export = export limit (kW) × window hours (Flux/Cosy peak = 3 h). G98 (connect-and-notify) ≈16 A per phase ≈ 3.68 kW. DNO fast-track routes: NGED SGI-1/2 ≤16 A per phase, SGI-3 ≤60 A per phase (~13.8 kW at 230 V), all type-tested. ENWL fast track: Intrinsic Design Capacity ≤32 A and aggregate ≤60 A. Export limitation (G100) lets a larger inverter connect with a lower export cap. Charging/self-use is not limited by the export cap, but export arbitrage is.

Should I choose a battery based on export tariff income?

Be cautious. Export rates can fall: Outgoing Octopus Fixed dropped from 15p to 12p per kWh on 1 March 2026, its first change since 2022. Using stored energy yourself avoids the full import price, about 26p under the October 2026 cap, so self-consumption is the steadier basis for a business case; treat export and VPP income as a bonus.

Self-use value ~26.32p vs fixed export 12p (Oct 2026). Premium export deals are often tied to a supplier or installer and can be withdrawn. SEG minimum rates from some suppliers are 2-6p (existing tariff rows).

What to do next

Use your own half-hourly electricity data where possible. Compare usable kWh, kW, tariff rules and warranty terms before buying.

Sources

Last checked: 24 September 2026