Why car parks are the hottest space in solar power

There is more to this parking lot than just cars and empty spaces. Huge rows of angled solar panels sit atop jet black steel supports, absorbing the sun and shading the vehicles below.

A total of more than 2,000 panels with a peak output of almost 1 megawatt (MW) now stand in front of the offices of a large automobile manufacturer in southern England.

That’s enough to power hundreds of homes.

“They look stunning,” says Guy Chilvers, Business Development Manager at SIG, the company that supplied the solar roofs.

These buildings make parking lots more visually appealing, he emphasizes and admits: “I would say that too.”

Solar parking spaces or carports enable electricity to be produced in open spaces, which are usually located near energy-guzzling facilities such as hospitals, shopping centers or offices. The canopies have the added benefit of protecting cars from rain and snow or from the hot sun in summer.

To encourage the generation of clean energy, the French Senate recently passed a law requiring the covering of all existing and new car parks with 80 spaces or more with solar panels.

Whilst there is no such requirement in the UK, solar parking has been around for years and there are signs that it is booming here. With electricity prices still high at the moment, many companies are turning to on-site renewable energy to keep costs down over the long term.

There is a big opportunity to convert more UK car parks to solar farms, according to a new report from rural charity CPRE and the UCL Energy Institute.

“We estimate that the total potential of the built environment is around 117 GW,” says Prof Mark Barrett of UCL. “And of that, in our opinion, 11 GW are parking spaces.”

For comparison, the UK currently has around 15 GW total solar capacity and will need 40 GW by 2030 to reach net-zero targets, according to Solar Energy UK.

Prof Barrett points out that the figure of 11 GW is conservative and based on an estimate of 130 square kilometers of available car parking space in the UK – less than the 200 square kilometers estimated by estate agent Knight Frank. The CPRE and UCL report also assumed that 50% of each individual car park would be covered by a canopy instead of 100%.

Any way you look at it, there’s plenty of room in parking lots for solar panels, and people are starting to realize that.

“It’s gone absolutely insane,” says Mr Chilvers, referring to his inbox. Recently he is quoted for hotels, hospitals and leisure centers. Mr. Chilvers and his colleagues design and build the steel structures for solar roofs, while the panels are supplied separately.

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Competitors speaking to the BBC also reported high demand for solar park canopies.

Spain-based Praxia Energy delivers around 3MW of solar panels to car parks in the UK each year and expects that number to increase tenfold by 2028.

A spokeswoman for Veolia says the company has recently installed a 1.1MW solar canopy system in Eastbourne Hospital’s car park and the company has recently seen increased demand for solar infrastructure in the UK.

Solarsense, a Clevedon company, says it has also received increasing inquiries in recent months.

Tim Evans, chief executive of 3ti, argues that the UK has historically been slow to advance this technology compared to countries on the continent. “We’re pretty far behind the curve,” he says.

However, there are already some prime examples. The largest solar park installed in the UK to date is at the Bentley car plant in Crewe with a peak capacity of 2.7MW.

Mr Evans says he is currently evaluating four new potential projects with customers that could reach peak capacity in excess of 5MW.

Solar panels in parking lots can also enable electric vehicle (EV) charging. This works particularly well in offices where employees’ cars are parked outside for many hours. Shopping malls, football stadiums, leisure centers and cinemas are also suitable venues, as cars are typically parked for two hours or more to allow for sufficient charging, says Mr Evans.

However, the steel supports required for many solar roofs add to the cost. It is often cheaper to simply mount solar panels on the roof of large buildings, such as supermarkets. Mr Evans estimates that rooftop solar panels currently provide around 9p per kWh of electricity, compared to 14p or 15p per kWh for panels in car parks.

However, there aren’t many other obvious downsides to canopies, says Richard Watkins of the University of Kent. He points out that installers may want to equip them with efficient lighting under the canopy to avoid creating dark, potentially dangerous spaces at night.

A problem that many renewable energy projects are currently facing is the lack of grid connections, since excess energy generated by solar panels, for example, has to be routed to the grid. According to a BBC study, the problem has effectively put billions of pounds worth of investments on hold.

“I’ve just been turned down a megawatt lot, a beautiful lot, for a factory because it’s not connected to the grid,” says Mr. Chilvers.

A spokesperson for Solar Energy UK is also highlighting the problem, saying the imminent spread of solar parking remains “a long way off” until the problem is resolved.

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

As well as car parks, there are many other sites across the UK that could also house solar panels and help us move off fossil fuels, notes Newcastle University’s Prof Sara Walker. For example bike paths and railways or reservoirs that can be covered with floating solar panels. These also help to reduce the evaporation loss of water from reservoirs.

“If we can place solar photovoltaics next to infrastructure that would be there anyway, like a parking lot, we can double use the land area,” she says.