The government hopes the plug-in panels will offer people a more affordable way into solar energy compared to roof installation, although savings will be lower because they generate less power.
A one-panel kit will cost £699 while two-panels will be £1,089, according to UK solar company UKSOL.
The current regulations only allow people to plug in one device per property, but this may be changed in future. A single device may include more than one panel.
The government expects prices to settle at £400-£600 as competition increases and more products are developed.
Its research shows a household could save between £70 and £110 a year on their energy bills.
The precise amount will depend on how the panels are orientated and how long they run. An unshaded south-facing spot is best.
Households which use energy during daylight hours will benefit most as the electricity must be used as it is generated.
Any power not consumed will flow back to the grid, but it’s unlikely homes will get any cash for this.
Unlike rooftop solar panels, these systems do not need to be certified under the official Microgeneration Certification Scheme (MCS), which is the UK’s official quality mark for small-scale renewable energy systems.
But it also means they will not normally qualify for the Smart Export Guarantee that pays people for excess solar power.