When the Beatles released Here comes the sun back in 1969, as part of the album Abbey Road – the idea of installing solar cells in cars already existed. William Cobb – an American businessman – unveiled a 38 cm-long vehicle during the 1955 edition of the General Motors Powerama Auto Show. What he – as well as John Lennon and Paul McCartney – couldn’t know is that 67 years later, Lightyear would also introduce the first solar car in the world.
Lightyear nowadays is one of the leaders in solar cars. It is headquartered at the Automotive Campus of Helmond, Netherlands. Founded in 2016, it made headlines for its way of envisioning sustainable mobility. Lightyear’s concept revolves around a powerful solar power system, which – in addition to powering vehicles with green energy – aims to reduce reliance on the electricity grid.
The Dutch company launched its first model globally last June – Lightyear 0 – and also announced that production will start in the fall and delivery of the first models to customers in November. The manufacturer plans to launch its second car by 2025, which is expected to have a lower price tag than its predecessor – at a cost of €250,000. Lightyear 0’s 60 kWh battery pack can drive 625 km on a single charge, but solar power can extend the distance driven.
“Mobility is a human need. The fact that we can travel makes us happy and it is a part of us, we see new places, visit friends and explore just by being on the move,” says Emanuele Cornagliotti, Lightyear’s solar lead engineer. In its vision for a more sustainable way to travel, the Dutch company, the Dutch company puts efficiency as the cornerstone principle guiding all kinds of design choices.
As efficient as it can be
In order to be sufficiently efficient, the aspect of drag must be taken into consideration first. Also known as air resistance, drag describes the forces that are in opposition to the relative motion of an object as it passes through the air. Automobiles, trains and airplanes counteract this force by exerting a force that makes them move at the desired speed. Air resistance is proportional to speed, since it increases as acceleration increases. Less drag implies using less energy to move and consequently being more efficient. This aspect is particularly relevant to electric vehicles, since today’s batteries have a shorter range than those that run on fossil fuels.
Aerodynamics plays a crucial role in designing a car. In Lightyear 0’s case, engineers came up with a double curvature on the solar panels. “It is a matter of compromise. Choosing a flat option would have compromised aerodynamics. Also, shaping the car differently would have resulted in a smaller solar surface,” Cornagliotti explains further.
In Lightyear’s idea of efficiency, making the most out of the car surface was also a point to take into account. Lightyear 0 has 5 m2 of solar cells covering the roof, the bonnet, and the rear of the vehicle. Other manufacturers are opting for engraving solar cells on the doors too, but that’s not the case for the Helmond-based company. “Vertical photovoltaics have half of the yield of horizontal ones. Adding them to the car would have meant increasing costs without any significant energy production. Not to mention that those parts are much more prone to bumps – even minor ones. Aesthetics also influenced our choice,” Cornagliotti stresses. These decisions are paying off. In a recent wind tunnel test held in Germany, Lightyear 0 scored the lowest drag coefficient for a production car.
Maximizing harnessing of sunlight
The solar panels are the tip of the iceberg of a much more complex system that makes the most out of the sunlight that the vehicle harnesses. No matter how efficient the car may be, the way energy is handled is influential.
“First, you have to make sure that energy goes wherever you need it at that moment – it could be to the low-voltage battery or the high-voltage one. At the same time, it’s fundamental to have as few conversions as possible. Every conversion step results in the loss of some energy,” the engineer points out.
All efforts to collect sunlight would be useless without an efficient connection between the solar panels and the batteries. Specifically, this consists of a DC-DC – direct current – conversion to the battery pack. This is done by Lightyear through the use of an algorithm. It tracks the highest power point of the solar array, so that it can deliver the maximum amount of power at every given moment.
Emanuele Cornagliotti
Solar lead engineer at Lightyear
Having a Ph.D. in photovoltaics technology, he worked in developing solar cells and modules, before joining Lightyear in 2020.
Panels on the road
Being a kind of moving solar park, other aspects come into play as well. Coping with road vibrations, for instance, was solved by developing interconnectors between cells that make sure that vibrations don’t alter the performance of the solar panels. Efficiency over time is guaranteed – like household solar panels that can harness the sun for over 20 years – and maintenance isn’t needed. Although, as with every other vehicle, collisions can happen.
“Minor impacts don’t affect the functioning of the solar panels. In case of more severe cracks,these can be repaired just like a windshield. When the damage is too much and can’t be fixed this way, it’s better to replace the panel, because a new one will still produce electricity,” Cornagliotti adds. “However, it won’t be hermetic anymore and, therefore, more prone to early degradation. Still, there’s less risk in comparison to a windshield as far as being damaged by stones while traveling is concerned, since the panel is not as vertical, and therefore less slanted towards the road.”
No longer reliant on the grid
Lightyear estimates that – on a sunny summer day – solar cells can add up to 70 more kilometers of driving range. Every year, that can add up to as much as 11,000 km – if you live in Southern Europe. In the case of the Netherlands, engineers calculated that this figure would amount to no less than 6,000 km per year.
“These figures are predicated on outdoor parking during daylight,” Cornagliotti emphasizes. “They are considerable amounts, particularly for those who drive maybe 10 or 15 thousand kilometers a year.” As electricity – possibly clean – will increasingly power households, cars, and companies, the risk of grid congestion will be more likely too. Electric cars driving longer off-grid would as such be less dependent on the deficits and surpluses that grids have.
Solar mobility to be the new standard
Although such a transition won’t happen overnight, Cornagliotti firmly believes in solar mobility. “In 20 years, most cars will have solar body parts. This is for three reasons. Firstly, we will need to deploy photovoltaics – PV – everywhere, particularly as close as to where the energy is being used. Secondly, electric vehicles will be pushed more and more towards becoming as efficient as possible, and regulation will play a role in this. Lastly, PV technologies will reach even higher levels of efficiency, and their costs will still go down.”
Eventually, the sun came out. And it’s here to power our journeys.
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