For many years, we have been using solar power to produce electricity – and there have also been attempts to develop solar-powered cars. Team Sonnenwagen succeeded in its attempts and is today able to take part in Solar Challenge races with its Photon car. Read on for an exciting report from the Sonnenwagen specialists and learn about their innovative development – the Covestro Photon solar car.

What is the Covestro Photon?

The future of climate-neutral driving lies in solar power. Since 2015, Team Sonnenwagen has been developing solar racing cars. A team of students from RWTH Aachen University and Aachen University of Applied Sciences are collaborating with Team Sonnenwagen Aachen to design solar cars with which they can take part in Solar Challenges. The Covestro Photon is the third generation of solar car they have created. It is a solar electric car powered via solar panels. Efficiency was crucial in the design of the Photon: due to its catamaran design, the Covestro Photon is only half as tall as a racing bike, which means its aerodynamic drag is extremely low. The design also ensures high stability and enables high cornering speeds.


The solar cells were laid overlapping each other, allowing the new Photon to use 95% of the area efficiently for energy production. The electric motor, developed in-house, also ensures the necessary drive. To ensure that the driving strategy is also optimally considered and efficient, Team Sonnenwagen developed a new piece of software which automatically controls the speed using GPS and weather data. The driver can therefore focus fully on the traffic and steering.

Solar Challenge Morocco 2021 – Team Sonnenwagen reports

Solar Challenges aren’t simply called races. And for good reason, because they are much more than that. They begin much earlier than at the start of the race and are thousands of kilometres long. Solar Challenges last 2 years and include countless working hours, harsh setbacks and unbelievable achievements. When we set off for Morocco at the start of October, none of us had any idea what was ahead of us. And now, after a few weeks back in Germany, we still can’t put it into words – but this is at least an attempt to do that.

First stop Marrakesh, or rather Ben Guerir – a small place about an hour’s drive away from the Red Pearl. Each day, we commute between our workshop in the secure premises of an energy institute and the hustle and bustle of the city. To begin with, we’re all a bit overwhelmed. And why wouldn’t we be, when we have to ask for receipts for every business expense – the greengrocer on the corner thinks we don’t trust him! A group of Europeans attracts attention and at times also excitement, yet we receive a friendly welcome and make friends with many people, and even a few cats. But our main focus is on the Photon – we still have to put the finishing touches in place before the start of the race.

After a few days, we move to our second accommodation in a hostel in a suburb of Agadir, the town where the race begins. Our new workshop is actually on the site of the stadium that marks the starting point of our race. And the more Solar Family teams come together, the more serious things get. Just a few days to go until the start of the race. The clock is ticking.

Team Sonnenwagen prepares itself and its Photon for the Solar Challenge

With test laps, final improvements, little “features” and adjustments, we squeeze the last drop out of our Covestro Photon. Every day we set off for the stadium where we apply foils to our support vehicles, tighten chassis screws “just one last time” and check the drive train again and again. We all know the Photon has to be well prepared. 12,000 metres elevation gain, 2,500 km distance, countless potholes and one or two flocks of sheep stand before us.


The qualifying

Then comes the first challenge: the qualifying. A fully prepared Covestro Photon lines up to take pole position. We have done tests in the last few days, so we know we can do it. The warm-up lap goes well and we set our stop watches. But they run on longer than expected and it becomes clear that the Photon has had an accident. A tree trunk on the racing line has shattered our dreams in a split second.

Repairing the Covestro Photon

The feeling of seeing two years of work smashed to smithereens on the road – we wouldn’t wish that on anyone. Kevin, our driver, is in shock. But he has our full respect. Less than 12 hours until the race – can we repair the car? Then team shifts into what we call “solar car mode”. We get together, come up with a plan and everyone begins doing what they do best. Never has the analogy of a beehive been more appropriate. The chassis team fetches the spare parts, the structural components team begins repairing the places damaged by the tree trunk using adhesive and wet layup. The electrical engineers take a look at the mechanical damage on the battery. And soon it’s clear: it will be a lot of work, but we can do it! We will be able to drive tomorrow!


The Solar Challenge Morocco 2021 – the race begins

It is 9 am on 25th October and the Photon rolls onto the Moroccan road. We are in the race! Our euphoria doesn’t last long, because we soon notice that a few more errors have crept in. The solar cells are no longer supplying the battery with sufficient energy. What can we do about that? We stop at a filling station and repair PCBs on the solar car in front of 100 school children. Like we said – Solar Challenges aren’t called challenges for nothing. The first day doesn’t go how we planned. We fall into bed – some of us have been awake for more than 48 hours. Between huge dunes and a perfect view of the Milky Way, we hope day 2 is better. And it is! A couple of electrical engineers worked through the night again and so the Covestro Photon is ready to drive again. The lead car drives in front of it, pointing out every pothole, chasing dogs off the road with its horn and protecting the Photon against all hazards. Behind it, the driving strategy team, ensuring the optimal speed and line driven. What an amazing feeling! Hairpin after hairpin, we move closer to the day’s finish. In the end, we don’t have enough energy to get all the way to the end of the stage – the first day had cost us too much. But we proved to ourselves and everyone else that we were able to drive. Anyone who still had any doubts fell silent on day 3.


The Covestro Photon catches up

We set off and initially overtake Team TopDutch from the north of the Netherlands. We continue without interruptions and, for the very first time, have time to look left and right and appreciate the landscape we are driving through. Red mountains are bordered with palm trees with streams snaking through them, waiting for the next rain. We drive through small villages, climb steep hillsides, see dromedaries nibbling the last few withered leaves on the trees. People can barely believe their eyes when we drive through towns whose roads are shared by donkey carts, cars and traders. And things continue to go brilliantly.

We overtake Vattenfall – another top team from the Netherlands. The Covestro Photon is driving and that is truly balsam for the team soul. We reach the end of the stage in third place. An incredible feeling of relief sweeps over us. We climb the red dune in Merzouga and prepare for a relaxing evening. Even the sand storm that awaits us late in the evening and almost blows away our tents can’t harm us now.

Problems with the solar vehicle


Day 4 begins well thanks to the power of the last day. We schedule a short charging stop and then want to continue. But when we try to move the car a little bit, so that it is standing perfectly in the sun, we hear a strange noise. In that moment, we know that the charging stop will take longer than planned. A bracket for a shock absorber has come loose from the structure. We unpack our workshop and get to work, because this damage could definitely affect safety. So there is no question about it – we have to repair it. It’s a bit of a case of using a sledgehammer to crack a nut, because the bracket is more securely seated now than ever before.

Final spurt of the Solar Challenge

Once again we drive through breathtaking scenery and notice that the race is slowly coming to an end. We give our all and reach our next overnight stop with a time delay. The fifth and final day couldn’t get off to a better start. Thanks to our unexpectedly long charging stops, we have a lot more energy in the battery than required, so we can enjoy pushing it to the limits. After the last difficult mountain stage and a flat tyre – has there ever been a race without at least one flat tyre? – we drive the Covestro Photon to the finish line in Agadir. We aren’t allowed to go faster than 100 km/h, but we are still able to cross the finish line by the afternoon.


Full success for Team Sonnenwagen

We hug each other and celebrate one of the biggest adventures of our lives. We did it! 2,500 kilometres later, we are back in Agadir. We proved to ourselves and to so many others that it is possible to cover such a distance using only solar power. And now we would like to thank you! Thanks for sharing the thrill with us, standing by us even when things got difficult and celebrating with us when things went well! Without your support, the last 2 years would not have been possible. The Covestro Photon was so much more to us than just a car for a race – it was a challenge that we took on with great success.


How useful was this post?

Click on a star to rate it!

Average rating 4.2 / 5. Vote count: 5

No votes so far! Be the first to rate this post.

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?