Discussion of the problems of harnessing solar power to charge electric vehicles and improving their range.

With the issue of climate change driving politicians to commit to a carbon-neutral future, the pressure is on motor manufacturers to develop environmentally-friendly cars that,not only boast green credentials, but also operate as reliably as current models that are powered by fossil fuels.

While global sales of electric vehicles have rocketed in recent years, by as much as 57% year-on-year, over half of purchases are made in China, whereas consumers in western countries remain unconvinced by the electric option:
charging time is perceived to be slow, there are often insufficient charging points in working order and electric cars simply aren’t able to complete longer-range journeys on a single charge.

Photovoltaic panels are already a common feature throughout the world, typically adorning the roofs of domestic and commercial properties to provide electricity for heating, lighting and other appliances.

However, could there be an opportunity to incorporate solar panels within the body of electric vehicles in order to power them, avoiding the need to make lengthy or inconvenient stops at designated charging points?

Energy experts believe photovoltaic panels may be a viable option in the long-term and are already a feature of some versions of hybrid cars.

This year, Korean car manufacturer Hyundai released a hybrid model from its Sonata range that uses solar panels in the roof to charge the battery, improving fuel efficiency and reducing carbon emissions.

Both the Toyota Prius and the Karma Revero are also available with solar cell options, but crucially these are hybrid vehicles that combine electric power with traditional fossil fuels so are not, in themselves, all-electric cars.

Relying solely on photovoltaic panels to charge a vehicle’s battery is a more challenging problem. Hybrid vehicle batteries tend to be smaller than those of all-electric cars, so solar panels are likely to be more effective.

Even taking this into consideration, the benefits are questionable: Hyundai claims that solar charging on the Sonata could supply sufficient energy to power the car up to 1,300 kilometres a year – a tiny drop in the ocean for most motorists who average ten times this distance over a 12 month period.

Solar cells also add cost to the price of vehicles – a key factor that could dissuade consumers from choosing to purchase all-electric over traditional fuelled cars – as well as weighing more – again, a key factor that could determine the driving range of a solar-charged vehicle once operating in normal conditions.

Furthermore, while it is the photons in sunlight that are converted to electricity in solar panels, cloud cover is not considered ideal for optimum energy production, so in countries in northern Europe that enjoy variable weather conditions, it is unclear how effective a solar-powered electric car would operate or whether difficulties, such as reduced range, would occur.

New technologies, such as those proposed by the Fraunhofer Institute for Solar Energy, could offer an increase in driving range by up to 10%.

But as Andreas Bett, the institute’s director, explains, if truly carbon-neutral energy supply is to be achieved, “we have to promote the expansion of photovoltaics vigorously, even beyond house roofs and open spaces.

In the future, solar modules will be integrated into our already built environment even more, for example into vehicles.”

One company is forging ahead with plans to build a more efficient solar-powered electric car. Dutch start-up Lightyear plans to release the Lightyear One which is billed as the world’s first long-range solar car.

With four electric motors to drive the wheels and solar cells incorporated into the vehicle, Lightyear claims that a small battery could generate between 30 and 40 miles a day in sunny weather, with a standard EV charging system available as back-up for in-journey or overnight charging.

But this new technology comes with a catch: with limited builds planned while the Lightyear One remains in the design stage, expect the price tag to stretch to beyond £100,000, with more affordable vehicles only becoming available once large scale production is underway.