Sunlight Fuels This Car
The World’s First Solar-Powered Car Gets up to 450 Miles of Range on a Single Charge
The Lightyear One solar-powered car debuted in 2019. Image Credit: Lightyear
Arjo van der Ham, cofounder and chief technology officer of Netherlands-based Lightyear, is sitting in an SUV parked in California’s Silicon Valley. It’s sunny in San Francisco, just the way van der Ham likes it. He’s in the middle of a three-week tour to show off the first prototype of his company’s solar-powered car, Lightyear One.
“We are super motivated to build a solar car in which people will never ever have to worry about charging.”
Outside his window is a sleek silver car that’s been making headlines since the company unveiled it in June 2019. Fifty-four square feet of thin black solar panels cover the vehicle’s hood and roof, constantly charging the car’s battery as long as the sun is shining. Mileage will vary depending on climate and driving frequency, but if placed in perpetually sunny places that never encounter shade, Lightyear One could get 12,000 miles per year on solar power alone. In places with tree shade or if parked in garages, the car will get about 8,300 miles per year, and in cloudier places, like the Netherlands, it could get about 4,375 miles annually. But that’s not all. Like a conventional all-electric vehicle, the hyper-efficient Lightyear One can be plugged into a 240-volt socket (standard in the U.S.) or a DC fast-charging station to charge the battery, which provides up to 450 miles of range.
For a bootstrap company founded by university engineering students, Lightyear has come a long way since it launched in 2016. Today it employs 130 people comprising a mix of young talent and industry veterans. LinkedIn named Lightyear the best startup of 2019 in the Netherlands, and recently the international accounting firm Deloitte agreed to buy 1 million sustainable car kilometers from Lightyear as part of a lease agreement.
With momentum gaining, van der Ham and his team think they can reach their goal of logging a lightyear’s worth of solar miles, the equivalent of 5.88 trillion miles, by 2035. Hence the name of their company. Underlying that goal is a mission to free people from the electric cords that bind them to charging stations and to provide clean mobility for everyone. “We are super motivated to build a solar car in which people will never ever have to worry about charging,” the company’s CEO Lex Hoefsloot told an audience at the unveiling of the car. Fulfilling that mission will demand that they push efficiencies in electric car technology further than anyone has before.
Origin of Lightyear
The road to Lightyear started with a competition, the Bridgestone World Solar Challenge. This biennial race, which began in 1987, challenges teams of engineers to build cars that can travel 1,875 miles on solar power alone. The course spans mainland Australia, with a starting line in Darwin on the northern coast and the checkered flag in Adelaide in the south. Each team is forced to design a system that efficiently balances power resources with energy consumption, using no more than 64 square feet of solar panels. If the car goes too fast, it can suck up too much juice from the battery and stall. If it goes too slow, it can lose the race.
The car designed for the 2013 World Solar Challenge traveled 1,875 miles in 40 hours, 14 minutes, achieving a top speed of 74.6 mph.
The Stella solar car with Solar Team Eindhoven at the World Solar Challenge 2013. Cofounders Qurein Biewenga, CFO (left) Arjo van der Ham, CTO (second from left), and Lex Hoefsloot, CEO (to the right of car). Image Credit: Bart van Overbeeke, TU/e
Van der Ham had heard of the race but hadn’t given it much thought. While he was in his third year at Eindhoven University, studying electrical engineering, he started to form plans of going on for a master’s degree and then landing a job at a corporation. But one day out of the blue, fellow student Lex Hoefsloot asked to meet. Hoefsloot said he was building a team to compete in the 2013 World Solar Challenge, and he wanted van der Ham to join. Van der Ham wasn’t sure he wanted to come on board, but as the two engineers started drawing electrical diagrams on a chalkboard, he warmed to the idea. After an hour, van der Ham told Hoefsloot he’d go home and think about it. “By the time I got home, I was like, ‘What am doing?’ I called back and said, ‘Yup, I’m going to do it,’” says van der Ham.
That year, 20 students joined to form Solar Team Eindhoven. For almost a year, the team, advised by several faculty members from Eindhoven University’s Electrical Engineering and Mechanical Engineering departments, worked days, nights, and weekends to perfect the design of their car, which they named Stella. They entered it in the World Solar Challenge’s Cruiser Class, in which cars are designed for practicality. (In the Challenger Class, cars are single-seat aerodynamic machines built for sustained endurance.)
Billed as the first four-seater “family car,” Stella was built with lightweight materials and electric motors in the wheels to keep its weight at 840 pounds. Using MATLAB® and Simulink® from MathWorks, the team designed a highly efficient energy management system that helped make efficient use of solar energy while also reducing the weight of the battery. The car accommodated three passengers over the course of the race and achieved an average speed of 41.6 mph with a top speed of 74.6 mph. It finished the race in 40 hours, 14 minutes. Another team finished a little faster, but Solar Team Eindhoven received extra points for being able to seat more than one person. With a final score of 97.5, the team won first place in the Cruiser Class.
The cofounders advised the 2015 team in the design for the Stella Lux, which won the World Solar Challenge cruiser class again in 2015. Image Credit: Bart van Overbeeke, TU/e
Their winning solutions paid off again. Two years later, members of the 2013 team advised a new group of engineers from Eindhoven University, who won first place again in the Cruiser Class, with their car, Stella Lux. “People started saying, ‘This is cool, but when is it going to get to the market?’” says van der Ham. It began to dawn on the engineers that they could commercialize the technology. Hoefsloot, van der Ham, and two other members of the competition team, Qurein Biewenga and Koen van Ham, scraped together initial funding from their friends and families, and by the time engineering students from Eindhoven University entered the 2017 World Solar Challenge, Lightyear was off the ground.
Although van der Ham and the rest of the 2013 engineers played only a minimal role in Solar Team Eindhoven’s third World Solar Challenge in 2017, the team won with Stella Vie. In the meantime, Lightyear had organized an investor café and had begun pitching to larger investors. By spring 2019, they had secured more than $20 million in funding and were on their way to unveiling their first prototype that June.
Static charging the solar car Stella on day six of the 2013 Bridgestone World Solar Challenge. Image Credit: Bart van Overbeeke, TU/e
A Performance Mindset
The key to winning the 2013 World Solar Challenge was adopting a performance mindset, says van der Ham. They reduced the multifaceted problem of designing a car that balanced electricity generation with power needs to a simple question: How much energy do you need to drive one mile? And then, using MATLAB and Simulink, they optimized the solar panels, the battery, and the aerodynamics. For instance, when considering the car’s roof, they needed to find the right balance between a completely flat, wide shape that would maximize sunlight exposure, and one with curves that would reduce wind resistance. By running simulations in Simulink, they were able to scrutinize these kinds of design tweaks and see where the best tradeoffs were to improve efficiency.
They carried this mindset and the use of MATLAB and Simulink over to their commercial endeavor. As an early-stage company, Lightyear initially received access to products and support through the MathWorks Startup Program. Van der Ham says that this license was key to a smooth transition. All of the engineers they hired in the early days came from Eindhoven University, where MATLAB and Simulink were ubiquitous. Having access to the same technology as a startup company encouraged a smooth transition.
“You want your team to work efficiently and they work most efficiently if they are able to work with not only the best tools but also the tools they’re used to working with,” he says.
Their engineering expertise resulted in Lightyear One, an extremely lightweight, aerodynamic, and energy-efficient electric car. The team was able to limit the car’s weight to 2,870 pounds by using lightweight materials and a small battery pack and by incorporating wheel motors into each wheel instead of relying on one large engine and a drive train.
The car’s electronics efficiently convert sunlight into electricity and optimize how much energy the car draws from the battery. As a result, Lightyear One uses 160 watt-hours of electricity per mile.
Stella was entered in the cruiser class in the 2013 Bridgestone World Solar Challenge. Image Credit: Bart van Overbeeke, TU/e
“You want your team to work efficiently and they work most efficiently if they are able to work with not only the best tools but also the tools they’re used to working with.”
Lightyear One. Image Credit: Lightyear
Lightyear One’s aerodynamic shape adds to the car’s high efficiency. It’s long with a slope that resembles the cross-section of an airplane wing. Other decisions, such as adding wheel covers to the rear tires and replacing side mirrors with cameras, squeezed out even more efficiency. Wind tunnel tests showed that Lightyear One broke the record for being the most aerodynamic five-seater electric car to date.
Van der Ham says that as they grow the company, they’ll continue to build on their engineering expertise and draw from the most advanced tools to improve performance. “Good is not good enough; we’ll keep pushing to make it better all of the time,” says van der Ham.
