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July 31, 2020

Lightyear’s solar impulse

Lightyear’s solar impulse

September 2016 — Lightyear founded

Designing Lightyear One around the solar roof

With the belief that all cars should be energy positive in 2035. We started the development of our solar vehicles by designing around the system that will power it all: the solar roof. By maximising the solar yield we maximise the independence and amount of true sustainable kilometres for the end user. Our goal is to have one lightyear of solar kilometers by 2035.

The roof is designed as an integrated and structural part of the car, thus not merely an add-on. After analysing the trade-offs of energy yield and production complexity we decided not to include the solar cells on the sides of the car. On the hood and roof of the car, the solar cells are integrated with the glass roof. Doing the same for the doors of the car would increase the production complexity of the vehicle, add more weight for cables and the glass to the doors while the energy yield is relatively limited.

March 2018 — Velocity program start

Making the right trade-offs between solar yield, structural performance and aesthetics

To speed up the development of our signature solar technology, we teamed up with TNO in the Velocity Program, a research subsidised by Dutch government. Together we put the focus on the realisation of double-curved solar panels that could be integrated into the aerodynamically shaped roof of the car with special attention on manufacturing of the complete structure and the optimisation of the solar yield. By modelling different solar cell sizes and patterns, we were able to fully maximise the available surface, reaching the maximum number of cells per square meter and herewith increase the solar yield per vehicle. Within the same program we started designing a new manufacturing process in order to deliver an aesthetically pleasing solar roof, with optimised solar yield and structural performance.

September 2018 — First solar car integration

Solar yield optimisation & first solar roof prototype

Once we reached the optimal size and shape of the cells to maximise the solar surface, the solar yield was improved through the development of Distributed Maximum Power Point Tracking (DMPPT). This system allows small groups of solar cells within the integrated panels to operate at maximum power regardless of the other cells’ exposure to the sun. Meaning that a bit of shadow from a tree or lamppost doesn’t influence the yield of the whole system. The first deliverable of the Velocity program was the physical prototype of the solar roof for the exclusive Lightyear One design unveiling in September 2018 and the entire Velocity program was completed successfully in February 2019.

Lightyear one solar powered car


Lightyear One visiting California and the Bay Area in October 2019.


June 2019 — Unveiling Lightyear One & Accelerate program start

Developing and testing for automotive standards

With the learnings from the Velocity program we were able to create the integrated solar roofs for the prototype of Lightyear One. After the successful global launch, Lightyear and TNO initiated the Accelerate Program mid 2019 to take the technology even further.

In this Accelerate program we set out to ensure that the strict automotive guidelines are respected for our solar technology. This includes the further development of the solar roof, Lightyear’s DMPPT and a number of thermal and crash tests, all to ensure the technology is ready for the production of Lightyear One. One test for example entailed a heat resistance test simulating twice the power of the sun in order to make sure the roof is also able to handle additional influx generated from light reflected from the built environment.

September 2019 — Sunpower supplier partnership

Lightyear’s long lasting partnership with Sunpower was formalised in September 2019. In earlier years, Sunpower supplied the solar cells that led our founders to victory in the World Solar Challenge in 2013 and their successors in every edition since.

With custom sized solar cells using Sunpower’s Maxeon Technology, tested for stress, shock and thermal resistance, we were able to optimise our solar technology to last the lifetime of the car. Lightyear’s commitment to solar mobility was rewarded with Bertrand Piccard’s Solar Impulse label and was awarded one of TIME magazine's best inventions of 2019.

Tesla with solar powered roof


Lightyear’s latest Research Vehicle 006 driving around in Dutch nature


Spring 2020 — Validation with research vehicles on the road & Collaboration DSM

In the spring of 2020 we took the first steps in building a fleet of research vehicles in order to validate and test our solar technology and solar yield under driving conditions. Aiming for 30.000km driven with the solar areas realised on the research vehicles. The generated data will be used for further optimisation of the solar roof.

Having completed the initial development of our solar roof, we sought to proceed with commercialisation and signed a joint development agreement with DSM. With a focus on pilot projects in the automotive and transportation sectors, Lightyear’s Research Vehicles, feasibility studies with other corporate actors and extensive testing under all different use cases. We aim to generate a new solar impulse for electric vehicles.

Over the horizon

Looking ahead, we will focus on optimising the production process for the start of production of Lightyear One which is scheduled next year. Next to that we will integrate the solar roof with our own developed powertrain in the fall of 2020 and start real life testing with our next research vehicle from the start of 2021.

Finally, we have recently decided to leverage the B2B market for our solar technology. We are currently working with several automotive and transportation parties to integrate our solar technology on larger surfaced vehicles such as electric trucks and buses. Bringing us closer to reaching that goal of one lightyear of solar kilometers by 2035.


Lightyear’s solar technology, which powered the Stella that championed the 2013 World Solar Challenge, is at the heart of our company. Since founding Lightyear we have put solar technology development at the forefront of our company as we push to create our own disruptive advantage for commercial solar vehicles. Read about the milestones and developments of the integrated solar cells from the moment Lightyear started up until now.

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