Octopus Energy announced the Nook home battery range on 22 June 2026: a 2 kWh Cube that plugs into a normal wall socket with no installer, and a larger wall-mounted Colossus that stacks to 30 kWh. Pricing has not been announced, and UK availability is 2027. Everything else you have read about the Octopus Nook traces back to a launch keynote and Octopus’s own pages.
The headline claim deserves scrutiny. On stage, Octopus CEO Greg Jackson said a Nook will pay for itself “in two or three years”, even without solar panels. I run a 16 kWh battery on exactly the tariff arbitrage he is describing, so further down I check that claim against measured numbers. The short version: the arithmetic only works at a price no finished battery product currently sells for.
One thing to clear up before anything else, because the timing of the announcement invites the confusion: the Nook is not “plug-in solar”. Plugging a battery into a socket to charge is as legal as plugging in a kettle. Pushing solar generation into a socket is the thing UK law does not allow yet. The diagram below makes the difference obvious.
What did Octopus actually announce?
Two products on one platform. The Nook Cube is a 2 kWh battery you plug into a normal wall socket, stackable to 10.5 kWh, with no professional installation. The Nook Colossus is a wall-mounted, professionally installed battery in 5 kWh and 10 kWh sizes, stacking to 30 kWh. Both carry a 12-year warranty and arrive in the UK in 2027.
That is close to the full list of confirmed facts. The sources are the launch keynote at the Energy Tech Summit on 22 June 2026 and the Nook page on the Octopus website. Octopus has not disclosed who manufactures the Nook hardware.
Both products run what Octopus calls Octopus Intelligence: they charge themselves when grid electricity is cheapest on the smart tariffs, and you can override the behaviour in the app. Jackson gave the example of choosing whether your solar goes into the house or into the battery; the promise is that the defaults save money immediately and everything stays configurable.
The Cube is aimed at people who cannot have a normal home battery: renters, flats, anyone who cannot drill into a wall or pay for an installer. You plug it in, it charges when electricity is cheap, and because nothing is installed, nothing stops you taking it with you when you move. The Colossus is a conventional installed battery that will compete with the established brands.
| Nook Cube | Nook Colossus | |
|---|---|---|
| Capacity | 2 kWh per unit, stacks to 10.5 kWh | 5 or 10 kWh per unit, stacks to 30 kWh |
| Installation | Plugs into a wall socket, no installer | Wall-mounted, professional installation |
| Aimed at | Renters and flats | Owned homes |
| Warranty | 12 years | 12 years |
| Price | Not announced | Not announced |
| UK availability | 2027 | 2027 |
Two more things were said on stage that you should treat as launch claims rather than facts, because no pricing exists to check them against. Jackson said the Colossus will be “about a third cheaper than the best-known battery brands”, and that even without solar a Nook pays for itself “in two or three years”. The middle of this article tests the second claim.
Is the Nook the same as plug-in solar?
No, and the difference is the direction of power. A Nook draws electricity out of the socket to charge, exactly like any appliance, and that is legal today. Plug-in solar pushes generated electricity into the socket, and that is the part UK law does not allow yet. Charging a battery from a socket needs no rule change.
The confusion is understandable, because Jackson introduced the Nook minutes after talking about the government’s plan to make plug-in “balcony” solar easy. But these are separate tracks. The government consulted on the plug-in solar rule change in June 2026 and is analysing responses; there is no confirmed date for when plug-in kits become legal, and the interim product rulebook the government has published covers solar generators, not batteries. I keep the full state of that saga current in the plug-in solar rules guide.
One honest caveat, which connects to the unknowns list further down: Octopus has not disclosed how the Cube feeds stored power back to your appliances. If devices plug into the unit itself, no rule is involved. If it pushes power back through the wall socket, that is a compliance question Octopus has to answer before sale, not something you need to solve. Either way, the 2027 date rests on Octopus’s own production and pricing decisions rather than on the plug-in solar rule change.
Does the “two or three years” payback claim add up?
Only at a price no finished plug-and-play battery currently sells for. At today’s tariff spreads, a fully cycled 2 kWh Cube saves about £120 a year, so a two-to-three-year payback implies a launch price around £240 to £360. That is possible, but it would undercut every finished battery product on the market and land near the price of bare DIY cells.
Here is the mechanism. A battery without solar makes money one way: it charges when electricity is cheap and replaces grid electricity when it is expensive. On Octopus Go, the overnight rate is 7.5p/kWh between 23:30 and 05:30. The July to September 2026 price cap unit rate is about 26p/kWh. That is a spread of just over 18p on every kWh you shift. I walk through the full arithmetic, with my own measured system, in the battery storage without solar guide.
A 2 kWh Cube cycled in full every day shifts about 730 kWh a year. At that 18.6p spread that is roughly £135 gross. Batteries lose 10 to 15% of the energy in the round trip, and no battery cycles perfectly every day, so call it £110 to £120 a year in practice, and treat that as an estimate that assumes a cheap-window tariff and disciplined daily cycling, which is exactly what Octopus Intelligence is built to automate.
Now run the claim backwards. £120 a year and a three-year payback prices the Cube at about £360; two years puts it at £240. Per kWh of storage that is £120 to £180 for a sealed, app-controlled consumer product. The cheapest route I know today is DIY rack batteries at about £110 per kWh, and those are bare cells that still need an inverter and an electrician. My own 16 kWh system cost about £3,300 all in and pays back in a measured 3.2 to 3.4 years. If Octopus prices the Cube where the claim needs it to be, it genuinely is the “no-brainer” Jackson called it. Until a price exists, the payback claim is marketing arithmetic that cannot be checked.
The same test applies to the Colossus. Ten kWh shifting the same 18p spread saves roughly £590 a year at full cycling, so a three-year payback implies about £1,800 for a professionally installed 10 kWh battery. Notice that the two launch claims sit uneasily together. The best-known brand of all, the Tesla Powerwall 3, runs £8,000 to £10,500 installed for 13.5 kWh in my battery overview, which is roughly £590 to £780 per kWh. A third cheaper than that puts a 10 kWh Colossus at £4,000 to £5,200, and at £590 a year that is a seven-to-nine-year payback, not two or three. Both claims can hold only if the batteries earn well beyond the simple overnight spread, for example by chasing Agile’s volatile days or being paid for grid-balancing events. Which tariffs the Nook will support, and how well, is covered in my Octopus export tariffs guide if you want the current tariff landscape.
What does 2 kWh actually cover?
Two kWh is small. In the battery guide I use 1 to 1.5 kW as a typical evening baseload for a UK home, and one Cube covers that for about an hour and a quarter to two hours, a little less once round-trip losses take their share. It will not cook dinner: an oven pulls 2 to 3 kW and would flatten a single Cube in well under an hour, assuming the Cube can even deliver that much power at once, which Octopus has not specified.
What one Cube plausibly does is shave the most expensive evening hours off your background usage. The stack-to-10.5-kWh option matters because one unit does not carry a whole evening. Renters should read the £110 to £120 a year above as a per-Cube ceiling, not a floor: the saving scales with how much of your usage the battery can actually cover.
What is still unknown
Months, and possibly more than a year, before availability, the unknowns outnumber the facts. Here is the honest list:
- Price. The entire economic case rests on it, and Octopus has not announced one for either product.
- The full specification. Chemistry, weight, maximum charge and discharge power, and exactly how the Cube delivers stored power back to your appliances. That last detail decides how much of your evening usage one unit can offset.
- The manufacturer. Octopus has not disclosed who manufactures the Nook hardware.
- The date. “2027” with no month, no pre-order, and no waiting list as of July 2026.
- Tariff dependence. Whether the batteries work, or work well, if you are not an Octopus customer on an Octopus smart tariff.
None of this is a criticism. This is a normal unknowns list for a product a year from launch. It is only a problem if you read the launch coverage as a spec sheet. I will update this page when pricing or a full specification lands.
What would I do before 2027?
If you rent or live in a flat, the Nook Cube is the first product I have seen from a major UK supplier aimed squarely at you, and waiting for the price is the right move. There is nothing to buy or pre-order yet, and no waiting list to join.
If you own your home and want battery economics now, you do not need to wait: the arbitrage the Nook will automate already works today with an installed or self-built battery, at a measured 3.2 to 3.4 year payback in my case. The battery without solar guide covers the hardware, the tariffs, and the maths.
And if you came here because you thought the Nook meant plug-in solar had arrived: it has not. The rule change is still pending, and the plug-in solar rules guide tracks exactly where it stands.
Octopus Nook FAQ
When is the Octopus Nook available in the UK?
Octopus says 2027, with no month confirmed. The range was announced on 22 June 2026 at the Energy Tech Summit, and as of July 2026 there is no price, no pre-order, and no waiting list. Treat any more specific date you read elsewhere as a guess.
Is the Octopus Nook legal in the UK?
Yes, in the sense people mean when they ask: charging a battery from a wall socket is as legal as plugging in any other appliance, and the pending plug-in solar rule change does not apply to a battery drawing power out of one. How the Cube returns stored power to your appliances is not yet disclosed; that compliance detail is Octopus’s to settle before the product goes on sale.
Do you need solar panels for the Octopus Nook?
No. The Nook charges from the grid when electricity is cheap on a smart tariff and covers your usage when it is expensive. Octopus claims it pays for itself in two or three years without solar, which cannot be verified until pricing exists. With solar panels it also stores your surplus generation instead of exporting it.
