The survey found that London boroughs make up 23 of the 25 ranked bottom of the league table of all 380 local authorities in the country.
The government's up-take figures published in April 2013 suggest that 362,000 homes have installed solar panels in the UK since April 2010, which is the equivalent of about one roof in every 70, or around 7% of households.
Dumfries and Galloway, parts of Herefordshire and parts of Devon showed above average panel installation rates of about one in 40 roofs, while the Orkney Islands in northern Scotland have similar levels of installation despite sunshine levels, which are far below those in southern England.
But installation rates in London, the Welsh Valleys and the West Midlands lag far behind more rural areas in mid Wales and Cornwall, and this was consistent across the UK, said WSP.
WSP director David Symons said: "What seems clear is that - when combined with biomass, anaerobic digestion facilities and wind - there's an increasing trend for the countryside to be the renewable power station of the city.
"If solar panels are going to be one of our green energies of the future, our analysis shows there's a lot more work to do," Symons added.
"Poorer performer housing associations have to be highlighted, there needs to be more trust in energy companies and installers and, ultimately, panels have to become more efficient and cheaper."
Image: The survey found that the highest number of panel installations are consistently high in rural areas such as mid Wales and Cornwall. Photo: Courtesy of FreeDigitalPhotos.net.