Solar cells on the roof of your car and electricity from the side of the road: Solar mobility reduces vehicles’ dependence on the power grid and could be pivotal for electromobility.
In the debate about the future of mobility, the vision has long been clear: electric vehicles are what we want – climate-neutral, quiet, and emissions-free. But one challenge remains: the infrastructure for charging is lagging behind, particularly in rural areas, emerging countries, and places with poor network coverage. The solution could come from high up above: solar mobility. Solar mobility involves more than just charging electric cars with green electricity; it also involves integrating photovoltaics (PV) into vehicles. It is a concept that not only supplies energy, but also fundamentally changes the idea of mobility.
“Integrated photovoltaics can be used to encase buildings, roads, and vehicles in order to capture solar energy,” says Dr Martin Heinrich from the Fraunhofer Institute for Solar Energy Systems (ISE). This approach can be used for a variety of applications, including cars, commercial vehicles, buses, boats, ships, and even drones. The key advantage is that the energy is generated precisely where it is needed, in a decentralised, climate-friendly way, and potentially independent of the power grid.
Unlike conventional electric cars, which depend on external power sources, solar vehicles can charge themselves, at least partially. This technology is based on three pillars: fully integrated solar vehicles, hybrid models with PV panels on the body, and a solar-based charging infrastructure. Together, these pillars pursue one goal: greater self-sufficiency, lower operating costs, and a more decentralised system.
“Integrated photovoltaics can be used to encase buildings, roads, and vehicles in order to capture solar energy.”
Perovskite cells: The new generation of PV
The Lightyear 0 from the Dutch start-up of the same name
Perovskite solar cells are the lighthouses for solar vehicle technology. Regarded as the next generation of photovoltaics, they are lighter, more flexible, and cheaper to produce than traditional silicon cells – while also becoming increasingly efficient, explains Heinrich. An efficiency of almost 27 per cent has already been achieved in laboratory tests, trending up. Particularly exciting for the field of mobility is the fact that: “Perovskite cells can be applied to curved surfaces, such as car roofs or side walls, enabling completely new forms of design and integration. In combination with tandem cells, in which perovskite and silicon are layered on top of each other, even higher yields could be achieved in future, even in diffuse light,” says Heinrich. Organic photovoltaics (OPV) and thin-film technologies are also being developed further, particularly for lightweight, flexible applications in the vehicle sector. This brings us closer to a type of mobility that is self-sufficiently supplying itself with solar energy in a virtually invisible way – while also achieving better yields and a significantly lower environmental impact during production.
One example of fully integrated vehicles is the Lightyear 0 from the Dutch start-up of the same name, which developed e-cars from 2016 to 2023. With around five square metres of solar cells, this model can travel up to 70 kilometres per day in favourable conditions – using solar energy alone. In countries with high levels of sunlight, this is sufficient for the daily commute of many people. The German start-up Sono Motors took a similar approach with its Sion, whose outer shell also served as a solar panel. Although this project was a commercial failure, the idea lives on.
Well-established manufacturers such as Nissan, Hyundai, and Toyota also offer models with configurable solar roofs. However, this remains a niche offer for now: “It’s still more of a lifestyle thing and doesn’t appeal to a broad segment of buyers,” says Heinrich.
Public transport is taken to a new level
The Osnabrück Sunglider concept was awarded the top prize at the NY Product Designs Awards 2022 out of 500 entries from all over the world. The picture shows a visualisation of the solar levitation train at Neumarkt
A key area of application is local public transport. Solar mobility shows its strengths precisely where vehicles run regularly and travel predictable routes. In Osnabrück, for instance, the ‘Sunglider’ project demonstrates how an intelligent ‘upperground metro’ can be powered by PV modules along the route. The principle is simple: a tree canopy-like route structure with solar cells that generate green electricity for the trains gliding underneath. Thanks to inductive charging at the stops, the vehicles require no additional overhead lines. The result is an efficient, scalable public transport system that is CO₂ free, more city-friendly, and cheaper.
“We want to transform public transport by building a railway that runs into city centres via roads covered with solar panels,” says Winfried Heerbaart, who is part of the core team developing the Sunglider project.
To make the project more tangible for the general public, a test track for the Sunglider will be built on the site of the former Transrapid test track in Lathen, Emsland. “Starting construction this year would send a strong signal. After all, we are building on German engineering skills, infrastructure, and the tradition of vehicle construction in our region,” says Prof Dr Dieter Otten, Chairman of the Supervisory Board of Sunglider AG.
However, the potential of solar mobility technology extends far beyond public transport. Stefan Bachstein, Flat Laminates Manager at Brianza Plastica, believes that solar mobility technology has great potential in logistics in particular: “Solar mobility will play an important role alongside public transport, for example for the final mile of a journey.” When it comes to the commercial vehicle sector in particular, Bachstein believes that integrated photovoltaics are already economically viable: energy savings of between 22 and 29 per cent are possible – a clear argument for transport companies, municipal fleets, and parcel services.
Another aspect that is becoming increasingly important is the integration of solar mobility with the ‘vehicle-to-grid’ concept, whereby vehicles act as mobile storage units for renewable energies such as wind and solar power. In the future, vehicles could not only use this energy to power themselves, but also to feed electricity back into the grid, which would be an important contribution to stabilising decentralised energy systems.
And what about the price? Solar mobility makes both ecological and economic sense. While conventional electric vehicles currently cost between six and ten cents per kilometre to run, solar solutions cost between two and five cents. Operating costs are lower and the energy needed from the grid is reduced – a real advantage in times of rising electricity prices.
The movement’s pioneers can be found worldwide
Solar car from the Californian company Aptera
In Australia, start-up company Evie Networks is testing mobile solar charging stations for use in remote regions, while universities are developing integrated photovoltaic (PV) solutions for off-road vehicles. In California, Aptera is experimenting with ultra-light solar cars designed for efficiency and range, and Envision Solar (now Beam Global) is installing solar charging stations operated independently of the power grid. The United Arab Emirates is focusing on completely solar-powered vehicle fleets for inner-city traffic in its innovation city Masdar City.
The Swiss SolarStratos project involves the use of photovoltaics in aviation
Progress is also being made in Europe. In the Netherlands, Lightyear is developing production-ready solar vehicles with a range of up to 800 kilometres. In Switzerland, projects such as SolarStratos are demonstrating the potential of photovoltaics for aviation. Germany is also a major player in this field of research, with institutions such as the Fraunhofer ISE in Freiburg and university projects in Aachen, Stuttgart and Munich. Start-ups such as Sono Motors (which remains innovative despite its insolvency) and pilot projects such as Sunglider demonstrate that this country is also carrying out pioneering technological work.
Even if many of these names are not the word on the street yet, companies such as Aptera, Lightyear, and Envision Solar are setting international standards. They are all united in their attempt to reimagine mobility in an electrified, solar-powered, and sustainable way.
Solar mobility is not a cure-all, but it is a significant step towards climate-friendly mobility. It offers real alternatives where conventional charging infrastructure reaches its limits: it is decentralised, clean, and quiet. In the future, cars will not only be able to drive, but also to supply themselves with energy. And maybe even help to stabilise the power grid.
