Vehicles soak up the sun to help deliver power to the people

THE ANNUAL Sasol Solar Challenge is a showcase of solar technologies from across the world in which competing teams work hard to improve the technology and efficiency of their vehicles to clock up the furthest distance.

But how exactly do these solar cars work?

Event director Winstone Jordaan explained: “A solar panel converts ultraviolet energy into electricity. The electricity charges a battery, and the battery drives a motor.”

The solar vehicles used in the challenge need two things to optimise performance – a maximum power point tracker (MPPT) and a motor controller.

“The MPPT keeps the voltage constant and allows the amps to vary,” Jordaan said.

He said voltage was critical when charging a battery, and the MPPT helped to charge batteries more efficiently.

The motor controller worked between the battery and motor to make sure the timing of the signal that drove the motor was correct.

At sunrise each day, teams could be seen tilting their cars for maximum exposure to the sun before the start.

One morning, members of the Polish Lodz Solar Team stood a few metres from their vehicle, Eagle One, their long shadows falling just shy of the car.

Anyone who walked too close to the car was at risk of being tackled out of the way. Nearby, the Japanese Tokai University Solar Team placed traffic cones around their vehicle to keep people at bay.

Jordaan explained why it was important for the teams to prevent shadows from covering the solar panels on their cars.

“If you have three MPPTs, it means each MPPT has one third of the panel running on it. A shadow would cause the voltage to drop so far that the panel shuts down.

“The more MPPTs you have, the less susceptible you are to a shadow knocking out a whole panel.”

Jordaan said he was impressed by how much the efficiency of solar panels and motors had improved since 2014.

“The solar panels are getting very good. The efficiency isn’t changing a lot, but sensitivity to light is.”

This meant, for example, that the panels could still be charged even when the sun was at a low angle. Jordaan said the Solar Challenge was important because of its technological advances and innovations. “We’re developing the core technology for solar panels that will go on your home, and for electric vehicles.”