Plug-in solar panels hit UK supermarkets at £400

Asda and Lidl will put plug-in solar panels on their shelves within weeks, priced at roughly £400 each. The i Paper reports that the panels, built to be plugged directly into a household socket, are being positioned as a budget-friendly way for renters and homeowners to generate their own electricity. But the headline figure hides a more complicated reality for anyone hoping to slash their energy bills.

As reported by The i Paper, the panels are essentially small photovoltaic modules, typically 100–200 watts, with a microinverter and a plug that connects to a standard UK socket. No electrician required. No scaffolding. No planning permission. For the 4.5 million UK households living in flats or rented homes, that sounds like a door finally opening to solar.

Who qualifies, and who doesn’t

The panels are aimed squarely at households that cannot install rooftop solar: renters who cannot alter the fabric of the building, flat dwellers without roof access, and homeowners who want to dip a toe into generation without a £6,000 outlay. On paper, the target market is enormous. Of the 28 million households in England alone, roughly one in five is a private rental, and a further 20% live in flats or maisonettes.

But there is a catch: the plug-in panel must be connected to a socket that is on a dedicated circuit, not a standard ring main. Most UK homes have ring mains serving multiple sockets. Plugging a 200-watt panel into a bedroom socket could backfeed into the ring main, creating a risk of electric shock for anyone working on that circuit. The i Paper notes that some manufacturers recommend using a dedicated ‘solar socket’ wired back to the consumer unit. That requires an electrician, and adds £150–£250 to the upfront cost.

What it costs a typical 3-bed semi

A single 200-watt panel in a south-facing window or balcony in southern England will generate roughly 200–250 kWh per year. At the current price cap of 24.5p per kWh (October 2024–March 2025), that saves between £49 and £61 a year. Two panels double the saving to roughly £100–£120, but also double the upfront cost to £800 plus installation.

Compare that with a standard 3.5 kW rooftop array costing £6,000–£7,000. That system generates about 3,000 kWh a year, saving £735 at current rates, and qualifies for the Smart Export Guarantee, which pays roughly 15p per kWh exported. A plug-in panel does not qualify for SEG because it is not installed by an MCS-certified installer. The payback period for a single plug-in panel is around six to eight years. For a rooftop system, it is roughly eight to ten years. The difference is smaller than the price gap suggests.

EPC impact, negligible without certification

Energy Performance Certificates reward solar panels only if they are installed by an MCS-certified professional and connected to the grid via a Generation or Export meter. A plug-in panel that simply feeds into a socket does not meet those criteria. The Energy Saving Trust confirms that unmetered generation is not counted in SAP calculations, which underpin EPC ratings. So a £400 panel from Asda will not move a D-rated home to a C, no matter how many you stack on the balcony.

Yet the panels are not worthless. For a household that cannot install rooftop solar, a plug-in panel can still offset a portion of daytime baseload, the fridge, the router, the TV on standby. The key is to treat it as a supplement, not a solution. Ofgem data shows the average household uses about 2,700 kWh of electricity a year. A single plug-in panel covers less than 10% of that. Two panels cover perhaps 15%.

The i Paper reports that Asda and Lidl will stock the panels from mid-April. Before buying, check whether your home has a dedicated socket circuit or budget for an electrician to install one. And remember: no EPC uplift, no SEG payments, and no guarantee that the panel will survive a British hailstorm. But for £400, it is the cheapest way to generate your own electrons, and for many, that is a start.