The rules
- Up to 800 watts of output from the inverter (with up to 2,000 watts of panels behind it).
- Plug straight into a normal wall socket. No extension leads or adaptors.
- Use an approved kit listed on the official G98 Type Test Register, meeting the new plug-in solar product specification.
- Tell your network operator within 28 days, using a short online G98 form.
- Not on wooden structures or cladding, to reduce fire risk, under the new planning rules.
How much do they make and save?
A typical 800 W kit facing roughly south makes about 700 to 900 kWh a year. You only save money on what you use yourself while the sun's out, because plug-in kits can't currently get export payments.
If you used 400 kWh of it yourself, that would save about £105 a year at today's price of 26.32p per kWh.
Who they suit
- Renters: you can ask your landlord, who can't unreasonably refuse under the Renters' Rights Act 2025.
- Flats with a sunny balcony or garden.
- Anyone home in the day, who'll use most of what it makes.
The limits
- No export payments for now, because DIY kits can't get an MCS certificate.
- Plug-in batteries and all-in-one solar-plus-battery boxes aren't covered by the new rules.
- Much smaller savings than a full roof system. Compare with rooftop solar.
Sources: Fuse Energy summary of SI 2026/848, Planning Portal, Octopus Energy tariff data.