Why car parks are the hottest space in solar power

Apr 11, 2023

There's more than just cars and empty spaces in this car park. Huge arrays of angled solar panels sit atop jet black steel supports, soaking up the sun and shading the vehicles beneath.

Outside the offices of a major car manufacturer in the south of England, there are now more than 2,000 panels in total with a peak capacity of just under 1 megawatt (MW).

That's enough to power hundreds of homes.

"They are looking stunning," declares Guy Chilvers, business development manager at SIG, the firm that supplied the solar canopies.

These structures make car parks more visually appealing, he insists, while admitting, "I would say that".

Solar car parks or car ports enable electricity production in open spaces that tend to be positioned conveniently near to energy-guzzling facilities such as hospitals, shopping centres or offices. The canopies have additional benefits in that they protect cars from rain and snow, or hot sun in the summer.

In a drive to boost clean energy production, the French Senate recently approved legislation that makes it mandatory for all existing and new car parks with 80 spaces or more to be covered by solar panels.

While there is no equivalent requirement in the UK, solar car parks have been around for years and there are signs that they are beginning to boom here. With electricity prices currently still elevated, many businesses are turning to on-site renewables to try to keep costs down in the long run.

There is a huge opportunity to turn more British car parks into solar farms, according to a new report published by the countryside charity CPRE and the UCL Energy Institute.

"We think the total potential in the built environment is about 117GW," says Prof Mark Barrett of UCL. "And of that, 11GW, we think, is car parks."

For context, the UK currently has around 15GW of solar capacity in total and requires 40GW by 2030 in order to meet net zero targets, according to Solar Energy UK.

Prof Barrett notes that the figure of 11GW is conservative and is based on an estimate of 130 sq km of available car parks in the UK - lower than the 200 sq km estimated by estate agents Knight Frank. The CPRE and UCL report also assumed that 50% of each individual car park would be covered by a canopy rather than 100%.

Whichever way you look at it, there's plenty of space out there in car parks for solar panels and people are beginning to realise this.

"It's absolutely gone crazy," says Mr Chilvers, referring to his inbox. Lately, he's quoted for hotels, hospitals and leisure centres. Mr Chilvers and his colleagues design and build the steel structures for solar canopies while the panels are supplied separately.

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Rival companies that spoke to the BBC also described high demand for solar car park canopies.

Praxia Energy, based in Spain, supplies about 3MW of car park solar installations in the UK each year and says it expects this to grow tenfold by 2028.

A spokeswoman for Veolia says the company recently installed a 1.1MW solar canopy system in the car park of Eastbourne Hospital and the firm has registered increased demand for solar infrastructure in the UK lately.

Solarsense, a company in Clevedon, says it has also received rising enquiries in recent months.

Tim Evans, chief executive of 3ti, argues that, in the past, the UK has been slow to pursue this technology in comparison with countries on the continent. "We are quite some way behind the curve," he says.

There are some flagship examples already in place, though. The largest solar car park installed to date in the UK is the one at the Bentley car factory in Crewe, which has a peak capacity of 2.7MW.

Mr Evans says he is currently exploring four new potential projects with clients that could exceed 5MW peak capacity.

Solar panels in car parks can also power electric vehicle (EV) charging. This works especially well at offices, where employees' cars are parked outside for many hours. Shopping centres, football stadiums, leisure centres and cinemas are also suitable venues, since cars tend to be parked for two hours or more to allow sufficient charging, says Mr Evans.

But the steel supports required for many solar canopies do add to the cost. It is often cheaper to simply put solar panels on the roof of large buildings, such as supermarkets. Mr Evans estimates that rooftop solar yields electricity at about 9p per kWh currently, versus 14p or 15p per kWh from panels in car parks.

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.