Plug-in solar batteries in the UK: what you can buy and what it costs
Lidl at about £260, EcoFlow STREAM Ultra at £1,399, Thunder Energy at £1,699.99: batteries for balcony solar exist and vary tenfold in price. Here is what is on sale, what each is, and the compliance question none of them has answered.
Rules and product details last checked on .
Key takeaways
- Three different things are sold as a “plug-in battery”. A solar-charged battery with its own panel input, a battery built into a balcony kit, and a power station. Only some belong next to a plug-in solar kit.
- Prices span about tenfold: Lidl’s balcony battery at around £260, the EcoFlow STREAM Ultra X at £1,399, and a Thunder Energy kit with battery at £1,699.99.
- A battery you charge from your own solar panels is the safe category. A battery designed to draw power from your home’s circuit is what the statutory definition excludes.
- None of the products we found publishes evidence on how its storage fits the socket route, which is the open question in our battery guide.
- Payback is long. A battery does not generate anything; it moves generation from noon to evening.
Searches for “plug in battery” mix three products and two legal situations. This page separates them, then lists what we could find on sale.
The three things being sold
A solar-charged battery. A battery with a panel input, charged from a separate panel. Lidl’s balcony battery, reported by TechRadar on 29 May 2026 at around £260 with a 1,000 W input, is this type. It stores your own solar, which is a different proposition from a plug-in generator.
A battery inside a balcony system. EcoFlow’s STREAM Ultra X, listed at £1,399 with 3.84 kWh of capacity, and Thunder Energy’s “Storm Plus 710W Plug-In Solar Kit with Battery” at £1,699.99, bundle storage with generation.
A portable power station. A camping-style battery, charged from a wall or a panel, that you plug appliances into. It does not feed your home’s wiring, so it is not plug-in solar and it never reduces your bill.
The legal line
The statutory definition of a plug-in microgenerator excludes a device “designed to import electrical energy from a low voltage consumer’s installation for the purpose of storing energy for later supply”, other than for control functions the specification permits. In plain terms: charging a battery from your own panels is one thing, charging it from your socket is another. We quote the wording and the specification’s battery warning in our battery guide, and we could not find that any manufacturer’s page settles how its product sits on that line.
What it costs, and what you get for it
| Product | Seen at | Type |
|---|---|---|
| Lidl balcony battery | about £260 | Solar-charged battery, 1,000 W input |
| EcoFlow STREAM Ultra X | £1,399 | 3.84 kWh, generation plus storage |
| Thunder Energy Storm Plus 710 W | £1,699.99 | Plug-in kit with battery |
Prices are snapshots from 3 to 11 September 2026 listings and the TechRadar report. We have not tested any of them.
Is it worth it
The arithmetic is unforgiving. An 800 W kit produces roughly 500 to 830 kWh a year depending on city and mounting, our modelled figures. Daytime use already absorbs part of that, and an export is unpaid, so a battery recovers only what you would otherwise give away. That is worth having, but against a £1,399 price it is a slow payback, and we cover the cost side here.
What we have verified, and what we have not
Verified. The statutory exclusion wording and the specification’s battery warning, from our battery guide; the prices and product types, from listings and the TechRadar report on the dates given.
Not verified. That any product is certified for the socket route, its real-world capacity or payback, or Lidl’s product page, which we could not load.
Our editorial policy explains how we handle claims we cannot check.
Prices in this category move quickly. If you see a different live price, tell us and we will verify it.