What Octopus actually launched on 22 June 2026
At the Octopus Energy Tech Summit (ETS 2026) in London on 22 June 2026, CEO Greg Jackson stood on stage with a small grey cube and announced that Octopus is becoming the first major UK energy supplier to put its own home batteries on sale. The launch is in two parts.
Both units ship with Octopus Intelligence built in, which is the same Kraken-platform smart-charging logic that already runs Intelligent Octopus Go for EV drivers. The pitch is that you do not have to fiddle with charge schedules: the battery looks at your tariff, your half-hourly meter readings and the next day's wholesale prices, and dispatches automatically. Both products come with a 12-year warranty, which is at the long end of what UK home batteries currently offer.
The launch market is the UK, Germany, France, Italy and Spain, with sale starting "next year" (2027). No specific month has been confirmed. Octopus opened a waiting list on its blog the same day.
The price question Octopus has not answered
The thing the launch did not include was a price tag. What Greg Jackson did say was that the Nook Colossus will be "about a third cheaper than the best-known battery brands", and that the 2kWh Cube will pay for itself in "two or three years" without any solar panels. Those two statements anchor the maths in different ways.
Take the Cube first. A 2kWh plug-in battery on Octopus Go in 2026 looks like this:
| Cube assumption | Value |
|---|---|
| Usable capacity per cycle | around 1.9 kWh after round-trip losses |
| Charge rate (limited by 13A socket) | up to 3 kW |
| Octopus Go import rate (2026) | 9.5p/kWh |
| Octopus Go peak rate (typical, region-dependent) | around 32p/kWh |
| Saving per full cycle | 1.9 kWh × (32p − 9.5p) = around 43p |
| 365 cycles a year | around £155 a year |
| Plus typical Free Electricity Sessions capture | around £15 a year |
| Realistic Cube annual saving | around £170 to £200 |
For "two or three years" payback to be honest at those savings, the Cube needs to retail at roughly £400 to £600. That is feasible: similar-spec 2kWh plug-in batteries from Anker, EcoFlow and Bluetti currently sit in the £600 to £900 range, and Octopus has scale on its side. It would still be very keenly priced.
For the Colossus the anchor is different. The "best-known battery brand" Octopus is implicitly benchmarking against is Tesla Powerwall 3, which sells in the UK from around £7,499 fully installed for 13.5kWh of usable storage (about £555 per usable kWh). A third off would put the Colossus around £370 per usable kWh installed, or roughly £4,500 to £5,500 for a 10kWh unit. That is in the same neighbourhood as what Habo Energy already charges for its 11.5kWh system, so the Colossus is more "match the cheaper end of the UK installed-battery market" than "blow it up".
What is genuinely new about the Nook
Two things, in our read. The Cube is a real new product category for the UK. Plug-in batteries have been sold in Germany and Italy for a couple of years, but the UK market has been thin. The Cube is the first time a regulated UK energy supplier has put its own brand on a 13A plug-in battery with a 12-year warranty. That changes the conversation for the roughly 4.7 million English private renting households (per the ONS 2024-25 release) who have no install path for a wall-mounted battery, and pairs with what we covered on battery storage for flats and plug-in solar after BS 7671 Amendment 4.
Second, the Octopus Intelligence integration removes a friction point. Existing UK installed batteries (GivEnergy, Fox, Solis, Sigenergy, Tesla) all support smart tariffs, but the user has to set up charge windows and retune them when tariffs change. The Nook ships pre-bonded to the Octopus account, so charge windows, Free Electricity Sessions, Saving Sessions and future VPP dispatch payments happen behind the scenes. The trade-off is a tighter lock-in to Octopus as the supplier.
What is not new (and where to be careful)
A few claims have travelled further in coverage than the launch itself supports.
"Pays for itself in two to three years." True for the 2kWh Cube only if it retails at around £400 to £600 and cycles fully almost every day. For the Colossus, on the Octopus Go assumptions in our savings calculator, payback at the implied £4,500 to £5,500 price is more like five to six years. Still very good, not "two to three".
"Up to 10kWh from five Cubes." Mathematically yes (5 × 2kWh), but five separately metered plug-in batteries are not the same product as a single 10kWh wall-mounted unit. Each Cube draws through its own 13A plug, you need five spare double sockets distributed around the house, and you are limited to what each socket's spur can safely deliver.
"On sale in 2027." Octopus has not committed to a month. BS 7671 conformity and PAS 63100:2024 audits for the Colossus add lead time even after the hardware is ready. Plan on H2 2027 as a realistic Colossus on-shelf date, and the Cube somewhat earlier.
Wait or buy now: the twelve-month maths
If you are a UK homeowner with somewhere to put a battery, the question that matters is what waiting twelve months actually costs. There are three line items.
| Cost of waiting (per household) | Approximate value |
|---|---|
| Foregone Octopus Go arbitrage for 12 months | £800 to £950 |
| Foregone Free Electricity Sessions / VPP payments | £100 to £300 |
| 0% VAT on home batteries expires 31 March 2027 (per HMRC VAT Notice 708/6) | +20% on hardware and installation labour |
| Cost of waiting 12 months for the Nook Colossus | roughly £900 to £1,250 plus 20% VAT exposure |
For the Colossus to win on lifetime cost vs buying now, it needs to launch (a) before 31 March 2027 so 0% VAT still applies, (b) at a price more than £900 below the equivalent battery you would buy today, and (c) without a long install queue. The first two are plausible; the third is not under Octopus' control. The Nook will roll out alongside Octopus' existing waiting list for installed batteries, and ETS 2026 confirmed that demand is already heavy.
The position we land on is the same as our read on sodium-ion home batteries: waiting for a future product to undercut today's market is a real option, but the savings the current market delivers right now are not free if you delay.
Who the Nook genuinely suits
Strong fit: renters and tenants in flats who have no install path for a wall-mounted battery today. Leaseholders whose freeholder will not permit fixed electrical work. People who move every year or two and want a battery they can take with them. Octopus Go customers who already trust the Octopus app stack and would rather not configure a third-party battery.
Weak fit: owner-occupiers in houses with a meter cupboard, garage or utility room. EV-driving households where the battery economics are dominated by load-shifting tens of kWh of car charging (the Cube is far too small). Anyone whose 12-year horizon includes the 31 March 2027 VAT change and a likely supply constraint at Nook launch. People who want guaranteed whole-home backup during a power cut, which a plug-in Cube cannot deliver.
The wider context: supplier-brand batteries
The Nook is Octopus following a pattern, not reinventing it. Tesla pairs Powerwall with Tesla Electric UK (Ofgem licence granted 11 March 2026). British Gas has been quietly piloting subscription batteries. The direction of travel is supplier-owned hardware tied to supplier tariffs and supplier-run flexibility markets. More competition pushes installed prices down and flexibility payments up, both good for households. The thing to watch is supplier lock-in: optimisation, warranty and firmware updates are tied to the Octopus account, which makes switching energy provider more friction than it is with a GivEnergy or Fox box.
The bottom line
The Octopus Nook Cube is a genuinely new UK product category and the right answer for renters and flat-dwellers who currently have no install path. The Nook Colossus is sensible competition at the cheaper end of the installed-battery market that UK-focused suppliers already occupy, and not the price reset that the "third off best-known brands" headline suggests. For UK homeowners, the calculus has not changed: waiting until 2027 to buy a battery costs around £900 to £1,250 in foregone savings, plus exposes you to the 20% VAT change on 31 March 2027. Joining the Nook waiting list is free. Putting off the install is not.
Don't wait until 2027 to start saving
Habo Energy ships an 11.5 kWh home battery fully installed for £4,599, MCS-certified, with 0% VAT locked in and Octopus Go ready out of the box. Same supplier-agnostic Kraken integration, no waiting list.
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