The 2 kW cap on plug-in solar panels becomes law on 1 November, a change that could save a typical household £120 a year on electricity bills. The new permitted development right, announced by the Ministry of Housing, Communities and Local Government, removes the need for planning permission for these smaller systems. As reported by Engineering and Technology Magazine, the move is designed to make solar generation accessible to renters and flat-dwellers who cannot install roof-mounted arrays.
Who qualifies, and who doesn’t
The new rule applies to plug-in solar panels with a total capacity of up to 2 kW. That’s roughly six to eight portable panels, enough to power a fridge, a few lights, and a laptop. But there are catches. The panels must be installed on a flat roof, a balcony, or in a garden, not on a listed building or in a conservation area. Flats in blocks above ground level are excluded entirely. Ofgem confirmed to the BBC that plug-in systems will not qualify for the Smart Export Guarantee, meaning you cannot sell surplus electricity back to the grid. The Energy Saving Trust estimates that a typical 3-bed semi using 12,000 kWh a year would save around £120–£150 annually, assuming the system offsets 15–20% of consumption.
What it costs, and what it doesn’t do
A 2 kW plug-in kit costs roughly £600–£1,200, including panels, inverter, and cabling. At £120 a year saved, the payback period is five to ten years, comparable to a full rooftop solar array. But the comparison ends there. Rooftop systems improve your EPC rating by up to 10 points, which can add £1,500–£3,000 to your property value. Plug-in panels do not appear on the EPC at all because they are not fixed to the building fabric. Landlords hoping to boost a property’s rating for the Minimum Energy Efficiency Standard will need a permanent installation. The catch is that without EPC improvement, the financial case rests entirely on bill savings, no capital appreciation, no export income.
What this misses, and what the industry says
The Solar Trade Association welcomed the change but warned that the 2 kW cap is too low. “Most households could use 3–4 kW of portable solar,” a spokesperson told the Financial Times. “The cap should be reviewed within 12 months.” The bigger omission is the lack of a route to the Smart Export Guarantee. Ofgem argued that plug-in systems are too easy to disconnect and pose safety risks for grid operators. Yet the same technology is legal in Germany, where 1.5 million households use balcony solar without incident. The German cap is 600 W per unit, but multiple units are allowed, effectively no cap. UK homeowners lose out on up to £80 a year in export payments that their German counterparts receive.
What to do now
If you rent, live in a flat with a balcony, or cannot afford a full roof array, a plug-in system is worth considering from November. Buy from an MCS-certified installer to ensure safety and warranty cover. Check your building’s fuse box, older homes may need an electrician to add a dedicated circuit. And do not expect to sell power back: the savings come from self-consumption alone. For homeowners with a south-facing roof, a full 4 kW array still offers triple the savings and adds EPC value. The plug-in option is a step forward for renters, but for owner-occupiers, the full system remains the better bet.
Frequently Asked Questions
No. From 1 November, plug-in solar panels up to 2 kW are permitted development, no planning application needed. But they cannot be installed on listed buildings, in conservation areas, or on flats above ground level.
No. Ofgem has confirmed that plug-in systems do not qualify for the Smart Export Guarantee. You can only use the electricity you generate on-site, any surplus is lost unless you have a battery.
