The panels will go on sale in three stores - West Thurrock, Fulham and Croydon - from tomorrow.
It is expected to cost the average three-bedroom household£9,000 for enough solar panels to cover half its annual electricity usage.
Customers will receive a free in-store consultation with a trained adviser and receive a free assessment if their house is thought to be suitable. Installation is expected to take two to three days.
The retailer said customers investing in solar panels could expect to save 50 per cent on energy bills and cut carbon emissions by two tonnes a year.