The Costco signal: UK retailers are stocking home solar batteries

I keep a running note of where you can actually buy this hardware, because distribution is the clearest demand signal we have. So when I turned a corner in Costco this week and found pallets of EcoFlow and Jackery stacked between the Duracell and the decking, I stopped and photographed the lot. Warehouse retail does not clear floor space on a hunch, it clears it on numbers, and the numbers have clearly moved.

Before I read anything into it, I want to be precise about what is on that shelf, because the box marketing blurs a line that matters a great deal for what you are legally allowed to do at home.

What I actually photographed

Two brands, three products, one general-merchandise aisle. The EcoFlow DELTA Pro 3 was boxed as an "8000W Solar Battery, Plug and Play", rated 2600W with a 4000W surge, 4 to 12 kWh expandable, on UK 3-pin sockets, with a shelf tag reading £1,399.99 valid to 05 July 2026. Beside it, the EcoFlow DELTA 3 sat deep on the pallet as a "3600W / 1024Wh Solar Battery", and a few bays along, a full pallet of Jackery Explorer 500 solar generators, 512Wh and 500W, UK output, twelve boxes to the stack.

The company these products keep is the tell. This is not a specialist solar reseller or a niche online store, it is the same pallet economics as batteries and flooring, which is what mainstream demand looks like when it arrives. Currys already lists the full EcoFlow portable range online, so the warehouse floor is the physical edge of a shift that has been building in the channel for a while.

Germany ran this exact play, three years earlier

If you want to know where the UK is heading, Germany already drove the route. The pattern there was simple: the law simplified, energy prices spiked, the discounters put kits on pallets, and adoption went vertical. The registration numbers tell the story cleanly.

The German numbers are worth stating flat, because they are settled. Germany added 200 MW of balcony solar in the first half of 2024 alone, per pv magazine. Kits sold for around €500 at the supermarket, with a payback near five years, and a well-sited system covering roughly 15% of a household's electricity, according to Canary Media's September 2024 reporting. Solarpaket I took effect on 16 May 2024, lifting the inverter cap from 600W to 800W and collapsing registration into a single free entry in the Marktstammdatenregister, with the old grid-operator notification abolished. In July 2024 the Bundestag stopped landlords from arbitrarily blocking installs, per Reuters. Aldi, Lidl and Netto now run balcony sets as routine promotional lines, with Lidl partnering brand makers including EcoFlow.

Read together, those are the three ingredients: a law that got out of the way, a bill shock that gave people a reason, and a retail channel that made buying frictionless. Germany had all three by mid-2024, and the curve shows what happened next.

Where the UK actually sits

The UK now has all three ingredients in place. The retail piece is visibly here, and not only at Costco. Amazon, Asda, B&Q, Currys, Screwfix and Wickes all joined a UK government roundtable on plug-in solar in June 2026, and Lidl has backed the plan since March 2026, according to pv magazine. The bill-shock motive has been with UK households for three winters. The third ingredient has landed too: the enabling law was made on 16 July 2026 and plug-in solar became legal on 27 August 2026.

That last row was the whole story through the summer, and it has since turned over. The DESNZ consultation that closed on 30 June 2026 covered a change to plug and socket safety rules and an interim product specification, and notably it addressed connecting to a mains socket "without batteries", so the route unlocked first was panels only. Meanwhile the hardware already on the Costco pallet is battery-led. The market arrived from the battery end while the regulator opened the panel end, and the two have now met: register-listed panel kits are on sale and the batteries are on the warehouse floor.

What it means if you are buying this year

Two honest paths, depending on what you are actually trying to do. If you want backup power, or a way to use a portable panel on a balcony or in a garden, the power stations on the Costco floor are legal to buy and use today, and the warehouse channel means UK VAT, UK returns and UK consumer protection on a serious purchase. If your goal is solar that quietly offsets your daytime baseload through your home wiring, you can now do that by plugging a kit in. Update, 15 September 2026: plug-in solar became legal on 27 August 2026 under SI 2026 No. 848, and forty-eight kits from thirteen manufacturers are listed as Compliant on the ENA G98 Type Test Register, with 15 on sale and the cheapest at £432. A Compliant kit goes into an ordinary 13A socket and is self-notified to your network operator afterwards, with no electrician. A CPS-registered electrician and a hardwired connection are needed only for a kit that is not on the register. See the live register tracker.

So the shelf was telling the truth and a half-truth at once when I wrote this in July. It was true then that home solar and storage had gone mainstream in UK retail, and it was not yet true that you could buy a compliant plug-in solar kit and feed your ring main with it. That second half has now changed, and both things are still worth keeping apart before you spend.

What I said I would watch for has happened. The law came into force on 27 August 2026, register-listed kits are on sale, and the German curve and the UK shelf have lined up. The buying pages here have been updated to match. I still treat the Costco pallets as a signal about demand, and the ENA G98 Type Test Register as the thing that tells you what you may plug in.

Frequently asked questions

• Is the solar battery on sale in Costco legal to use in the UK?
  Yes. The Costco units, EcoFlow DELTA 3, EcoFlow DELTA Pro 3 and Jackery Explorer 500, are portable power stations and solar batteries. They power devices through their own sockets and do not export into your home wiring, so they are legal to buy and use today with no G98 notification and no BSI certification. The regulated category is plug-in solar that feeds the ring main through a 13A socket, which became legal on 27 August 2026 under SI 2026 No. 848. A kit listed as Compliant on the ENA G98 Type Test Register may be plugged into an ordinary 13A socket and self-notified afterwards.
• How far ahead of the UK is Germany on home solar?
  Germany passed 1 million registered balcony solar systems by June 2025 and over 1.3 million by spring 2026, according to the Bundesnetzagentur Marktstammdatenregister. Its curve steepened after Solarpaket I simplified registration on 16 May 2024 and discounters put kits on shelves. The UK has the retail piece moving and the law in force since 27 August 2026, roughly the position Germany held in 2023 to early 2024.
• Which UK retailers are moving into plug-in solar?
  Amazon, Asda, B&Q, Currys, Screwfix and Wickes joined a UK government roundtable on plug-in solar in June 2026, and Lidl has backed the plan since March 2026, according to pv magazine. Costco is already selling EcoFlow and Jackery power stations on the warehouse floor, which I photographed on 1 July 2026.
• Should I buy a solar battery from Costco now, or wait for plug-in solar?
  They do different jobs. A power station or solar battery is useful today for backup and for pairing with a portable panel, and it is legal now. If your aim is panels that feed your home through a socket, that route has been lawful since 27 August 2026. A kit listed as Compliant on the ENA G98 Type Test Register can be plugged into an ordinary 13A socket and self-notified to your network operator afterwards, with no electrician. A CPS-registered electrician and a hardwired connection are needed only for a kit that is not on the register. This is general information, not financial advice.