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Flat tyre costs SA Solar Challenge team dearly

Motorsport

Graaf-Reinet - 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 ultra- violet energy into electricity. The electricity charges a battery, and the battery drives a motor.”

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Teams tilt the solar panels of their cars towards the early morning sun to maximise their charging rate. Picture: Barry Aldwortht / eXpect Life

The solar vehicles used in the challenge need two things to optimise performance - a maximum power point tracker 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 can be seen tilting their cars for maximum exposure to the sun before the start. on Tuesday 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. Anybody 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. Their efficiency isn’t changing a lot, but their 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.”

Day Four - Gariep Dam to Graaf Reinet

The fourth day of the challenge saw the 11 teams cross the border from the Free State into the Eastern Cape. Strong winds throughout the day and a particularly challenging hill meant teams had to carefully strategise, to do as many loops as possible while keeping enough charge to make it to Graaff-Reinet.

Dutch team Nuon clocked the most distance with 586.1km, followed by Tokai and the Hungarian team’s MegaLux car. North-West University’s team missed out on a third-place tie with Megalux due to a 10.7km penalty, incurred by finishing late after a flat tyre cost 15 minutes next to the road.

The Star

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