Plug-in solar panels are now available in England, Scotland and Wales for the first time following changes taking effect on 27 August.
The systems use a microinverter to convert electricity generated by a small solar panel into power that can feed into a home's electrical circuits.
The technology could make small-scale solar generation accessible to some households that cannot install a conventional rooftop system, although people still need to check installation requirements and permissions, particularly when renting.
Energy Saving Trust says the change forms part of a wider Solar Roadmap aimed at increasing renewable generation and making solar more accessible.