Octopus Energy Spreads its Tentacles into Plug-and-Play Batteries

Plugging In to Savings: Octopus Energy’s Nook Cube Makes Stackable Battery Storage Actually Accessible

By eV Newt | 26 June 2026

We’ve heard a lot about ‘Balcony Solar’ recently - the off-the-shelf solar panels with inverter - that you simply plug into a mains socket in your house (yes really).

These panels can produce a decent amount of instant useable energy for the house, but if you don’t use this energy as it’s produced, it’s wasted and simply goes off into the grid. And without an export tariff to sell the grid your energy, it really has no additional financial benefit over saving on consumption.

What you really need with solar is battery storage as this transforms solar into a really powerful energy tool, shifting excess unused solar into storage for use later.

We had solar installed at home about five years ago and have a 9 kWp array comprised of 20 photovoltaic panels, plus we opted for 18 kWh of battery storage. This was not cheap as the battery made up a big part of the cost followed by labour costs for the installation, plus scaffolding costs.
As I own my house, installing such systems is relatively easy, but, for renters, this is something that they have been missing out on doing. It meant that they have had little choice but to pay for all the energy consumed and no option to reduce energy bills.

The problem (and why this matters)

Home batteries are brilliant on paper. They can be charged inexpensively overnight, and for free during the day via the solar panels. But the batteries can also be discharged when prices spike, and that pays owners very well, which in turn cut bills, adds inflationary resilience, and it helps the grid too.

Customers on smart tariffs have already saved hundreds of millions collectively by load shifting their usage. This is where customers buy energy when it’s cheap (normally overnight via a time-of-use tariff), and then store it until it’s needed when energy would otherwise be expensive.

Until now, the hardware side has been expensive for most people plus it requires DNO permissions and expert installation. It’s also not an option for renters, or anyone living in flats.

Octopus is trying to fix that with something properly simple, the Nook Cube.

What’s the solution?

Plug-and-Play Solar

Balcony solar is one good option that’ll soon be available to all, meaning base loads can easily be covered during the day with just a plug-and-play solar kit, but this is only half the story, because to extract the best from solar, you also need energy storage. Until now, energy storage has been somewhat challenging given its price and its need for a professional installation, so the other option is getting a ‘plug & play’ battery that simply plugs into your standard home socket. It seems too good to be true, but Octopus Energy have just announced such a system and that opens up solar and battery to a much wider market. It’s also fully transportable from home-to-home, too.

Nook Cube

At their Energy Tech Summit this week, CEO Greg Jackson announced the Octopus Nook range. This is a domestic stackable (expandable) battery storage solution, that doesn’t demand you own the house, drill into walls, or drop serious cash on a fully installed job.

The star of the show? The Nook Cube is a plug-in, stackable battery aimed at renters, flat-dwellers, and anyone who’s been locked out of the home battery party until now. And customers can add more capacity if needed.

The Nook Cube is a compact, shoebox-sized 2 kWh battery that plugs straight into a standard UK wall socket. No installer, no drilling, just unplug it and move house if you need to.

Want more capacity? Add extra units (called Cube Buddies) and stack them. Up to five units gets you around 10–10.5 kWh total, and everything is controlled through the Octopus app, which already knows your tariff, usage patterns, and when the cheap juice is flowing.

Do I Need Solar with a Nook Cube?

Even without solar, Greg Jackson says these should pay for themselves in two to three years just by arbitraging cheap grid power and avoiding peak rates.

But, add solar and it gets even better, as the system interacts nicely with the solar panels. Some early reports mention direct plug-in solar input options that could simplify things further, and no separate inverter required in certain setups.

The Nook Cube comes with a 12-year warranty - which is very decent - and it’s designed for self-consumption and bill saving rather than being a full off-grid monster.

Nook Colossus

For homeowners who can go the more permanent install and mansize system,  the Nook Colossus is a wall-mounted unit (5 kWh or 10 kWh base models) that can be stacked up to 30 kWh. These like my SolaX system require a proper electrical engineer installation, but it scales properly for bigger homes or higher demand. It has the same app control, same solar compatibility, and the same 12 year warranty.

Octopus Energy Nook Cube and Nook Colossus - Credit: Octopus Energy https://octopus.energy/

Why this feels different

This isn’t just another Tesla Powerwall rival. It’s direct from Octopus, a big, customer-facing energy supplier that puts skin in the game with hardware that lowers the barrier significantly, and levels the playing field for flat owners or people renting in the UK. It’s a realistic route to flexible storage without needing to convince a landlord or require a large loan, or remortgage to pay for it.

It fits the broader shift we’ve been talking about on Ctrl Alt Refuel for a while: the real win in energy isn’t just more renewables or more EVs – it’s flexibility at the edge by storing cheap, clean self-sourced energy and using it smartly. Batteries like this, paired with smart tariffs, make that possible without a heroic effort, or large expense.

Honest caveats (because we’re not here to shill)

•  It’s an announcement, not a launch. Real availability is 2027.

•  Exact pricing isn’t fully out yet, but it’s being positioned as far more accessible than big-ticket rivals, with some chatter suggesting that it’s significantly cheaper per kWh installed.

•  Output will be limited (Nook)by the plug  ~2 kW continuous – fine for household loads, not whole-house backup).

•  Full details on grid export, exact solar integration, and real-world app smarts are still to come.

•  You’ll almost certainly need to be (or become) an Octopus customer to get the best experience.

Conclusion

It’s a very welcome direction of travel that broadens solar and battery storage to a significantly wider audience, and allows customers to start small, and build it up overtime.

However, the Nook Cube is the most interesting element here because it’s a proper plug-and-play (or plug-and-stack) battery storage that could bring meaningful energy bill savings and energy flexibility to people who have been previously excluded.

Whereas, the Colossus gives the homeowners a solid scaled option too, that’s fully integrated into the home at source, and can draw more energy from the battery storage than the Cube, providing cheap, or free stored energy from the battery when the oven and electric hobs are on, for example.

We’ll be keeping an eye on pricing, real specs, and early customer feedback as the U.K. launch approaches. In the meantime, if you’re already with Octopus this feels like another reason to stay to lean into their flexibility tools.

What do you think? Drop your thoughts into our X feed @ctrlaltrefuel, or come and listen to us talk about it us on the next Ctrl Alt Refuel podcast episode.⚡

Deliveries

Both the Nook Cube and Nook Collosus are heading to Octopus customers in the UK, Germany, France, Italy, and Spain from 2027.

Credit: Octopus Energy https://octopus.energy/ for the use of the images.

Author

Newt is a lifelong car enthusiast and specialist in electric cars.

You can find Newt on𝕏 at @eV_Newt