The Holy Grail of electro mobility: solar powered cars.
Free fuel from the sky.
Kiss goodbye to worries about range and charging time.
A simple but brilliant idea that let two companies
who pursued it into bankruptcy:
Sono Motors in Germany and Lightyear in the Netherlands.
That we've seen, there's a lot of ways to ruin the concept.
They put everything into building their own solar cars and failed.
So what's the big deal breaker about solar cars?
First we need to understand how they work.
That's why we're here in Aachen, Germany
with the solar raceteam "Sonnenwagen".
So this is one of the most efficient electric vehicles in the world?
Yes. I mean, you can look at it, right?
It looks like a ping pong table basically.
So it doesn't have too much in common with the normal car.
This is Enno Dülberg.
Back in 2017, he was one of the founding members
of "Team Sonnenwagen" in Aachen, a team to participate in solar racing
competitions across the world, for example in Australia.
It looks a bit like a soapbox.
Yeah, like a bathtub, you could say.
And it rides a little bit like that, too.
So how many kilometres do we get out of this thing?
Depends, right? Depends totally on the sun, right?
If you're driving without the sun, it could be around 600 kilometres.
That's a rather small 6 kWh battery.
But if you have good sun, direct sun, then you
can drive indefinitely, you can just keep going.
Of course, it's depending on the speed then, right?
If you don't have too much sun, you have to go slower.
Unfortunately this solar race car needs to remain stationary today.
It has a top speed of 120 kilometers per hour
and is covered in four square meters of solar cells.
And it has only three wheels, with the engine sitting directly
in the wheel in the back.
For the car to be as efficient as possible, aerodynamics are key.
Just to give you an idea how light this is:
When I do this, the whole car is shaking.
How much does this weigh?
It depends a little bit on the battery chemistry,
but somewhere around 160 kilograms.
Yeah, it's just purely made of carbon fiber.
Everything is milled out of titanium or aluminium,
carbon fiber, so lightweight is definitely the way to go.
Because everything else is more rolling resistance.
And rolling resistance needs more energy.
The real crux of commercial solar cars
is that they are much heavier than this race car,
and solar can only produce so much power.
That's why making them run only on solar power is really, really hard.
Like every other electric vehicle, they also have
batteries that can be recharged on the grid.
But the solar cells are actually where bankruptcy started for
solar car startups like Sono Motors from Germany
and Lightyear from the Netherlands.
Because manufacturing these cells is quite complex.
Usually panels are straight, but in solar cars they need to be curved.
The electronics become more of a challenge when the surface
is quite curved because then one solar cell is looking at
the sun in a different way than the other solar cell and then you need
complex electronics to still get most of the yield out of solar.
But that's not the only challenge.
The cells should be robust and shouldn't splinter
if the car crashes.
And integrating them into a car part isn't easy either.
Buying the machines, buying the materials,
developing manufacturing processes.
And after you did all that, you need to get your newly developed
solar car parts certified for everyday streets.
All of this costs a lot of money.
Sono Motors would have needed 200-300 million euros
just to go into mass production.
No pocket money for startups.
But solar cells are only one part of the puzzle, the other one being
how many kilometers you actually get out of it.
And there are quite a lot of things to consider.
The size of the solar array: bigger means more generated energy.
Location on the globe:
some countries get more sun than others.
Time of the year of course, shading, dust on panels,
solar panels aging, which makes them less efficient, and more.
Projected ranges were 34 or 70 kilometres per day,
both promises that couldn't be kept.
Sono couldn't raise enough cash.
The company is restructuring and selling off their
car manufacturing capacities.
Lightyear underestimated manufacturing costs.
They plan to sell their Lightyear Zero for €120,000 but increased it
to €250,000 due to expensive car parts.
They filed for bankruptcy in 2023.
But what happens if you blow one parameter
completely out of proportion?
Something that is being tested right now by the truck manufacturer
Scania in Sweden in collaboration with Uppsala University, a real world
trial that has been going on since September 2023.
Instead of two square meters like most cars, the hybrid truck
has 113 square meters of solar cells that charge a battery in the trailer
for an estimated 5000 kilometers of added range per year.
We expect maybe somewhere around five to ten percent of the energy
that could come from solar energy.
And one should say that that is also in Sweden,
which is maybe not the best place to test this.
They even ran the numbers for southern Europe and
that could turn out twice as much energy.
So there are some great use cases for solar when vehicles are very light
and they are deployed in sunny regions
like here in Tunis with these delivery tricycles or these
small buses for public transport in Nigeria that mainly run on solar power.