Where we can co-locate solar photovoltaics alongside infrastructure that would be there anyway

There aren't many other obvious downsides to the canopies, though, says Richard Watkins at the University of Kent. He notes that installers might want to fit them with efficient under-canopy lighting so that they don't result in dark, potentially dangerous spaces at night.

One hiccup facing many renewable energy projects at the moment is a lack of grid connections, since surplus energy generated by solar panels, for example, must be handled by the grid. Billions of pounds worth of renewable installations are effectively on hold because of this issue, according to BBC research.

"I've just had a megawatt car park, beautiful car park, for a factory turned down because it can't get a grid connection," says Mr Chilvers.

A spokesman for Solar Energy UK also highlights this problem, saying that solar car parks becoming a common sight will remain a "distant prospect" until it is resolved.

The energy industry regulator Ofgem is looking at ways to speed up connections and National Grid also has a plan to improve the process.

There are lots of other locations around the UK, besides car parks, that could also accommodate solar installations and help us ditch fossil fuels, notes Prof Sara Walker at Newcastle University. Cycle paths and railways, for instance, or reservoirs that can be covered with floating solar panels. These also help reduce the evaporative loss of water from reservoirs.

"Where we can co-locate solar photovoltaics alongside infrastructure that would be there anyway, like a car park, it enables us to get double use out of the land surface," she says.