iESC Race Report #1

The iLumen European Solar Challenge (iESC) in Belgium has held the KO Chicane component of the event, under extremely wet conditions (see this!).

This component of iESC counts for 20% of final points. On mean times, Cruisers were 2.1 seconds faster in the Chicane than Challengers. The revised chart below (click to zoom) reflects the scoring (which, it must be said, has Bochum bringing home the bacon so far). Times shown are the best out of qualifying, semi-final, and final times. See also this excellent video.

Tomorrow is the big race. For fans at home interested in the weather, here is a webcam nearby, looking towards the Zolder racetrack. See also my iESC teams list and information page and the live timing board.


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Solar Car Racing Status Check #2


Tokai, who came 4th at WSC 2017, will race against Nuon at SASOL this year (photo: Anthony Dekker)

In further solar car racing news, preparations are continuing for the SASOL Solar Challenge in South Africa (September 22 to 30). Defending champions Nuon and Japanese team Tokai will attend this event, along with local teams, such as North-West University.


The Belgian car, Punch 2, which came 3rd at WSC 2017, will be challenging Twente at iESC this year (photo: Anthony Dekker)

Thirteen teams have registered so far for the 24 hour iLumen European Solar Challenge (iESC) in Belgium (September 19 to 23), and Twente will be defending their title there. I am maintaining an information page and teams list for this race. See also the official iESC social media at  


Western Sydney’s car, Unlimited 2.0, which came 6th at WSC 2017, will race at ASC this year (photo: Anthony Dekker)

Thirty-two teams have registered for the American Solar Challenge (ASC) in July. Scrutineering for this race begins on July 6, track racing on July 10, and the road race runs from July 14 to July 22. I am maintaining a detailed information page and teams list for this race too.


Missouri’s new car, Independence, was unveiled on 18 April (picture credit)

Five teams are attending with cars that raced at WSC 2017 (including one Australian team), although these cars will require adjustment to satisfy ASC rules. Seven other teams had existing cars (including one Russian team). The remaining teams have been building new cars.


Poly Montreal’s new car, Esteban 9, was unveiled on 23 April (picture credit)

Recently unveiled cars for the ASC include Missouri S&T (18 April), Poly Montreal / Esteban (23 April), and Georgia Tech (24 April). There are 17 cars still to be unveiled.


Georgia Tech’s new car, SR-2, was unveiled on 24 April (picture credit)


World Solar Challenge: Challenger dimensions

MostDece has written a superb blog post on the WSC challengers. Based on that, I’ve updated my previous post on dimensions. The infographic above (click to zoom) shows the reported length and width of 16 WSC cars (Challenger class only, this time). The widest car (at 2.05 m) is the South African car from NWU (below), but of course that includes the outrigger wheels. The narrowest is the long narrow bullet car from Michigan. There are also short zippy little cars from Nuon, Principia, and Punch.

Update: The chart below clusters cars with similar length/width combinations. NWU is a visible outlier. Below NWU, we have big cars (ITU, MDH, Adelaide, Aaachen, JU – over 1.6 m wide and at least 4 m long), short catamarans (Nuon, Principia, Punch – 1.55 to 1.6 m wide and at most 3.5 m long), narrow catamarans (Nagoya, Stanford, Twente, WSU – 1.38 to 1.5 m wide and at least 4 m long), and monohulls (Tokai, Kogakuin, Michigan – at most 1.2 m wide and over 4.9 m long):

Update: Unfortunately, the two charts above reflect incorrect information from the Stanford team. The Stanford car is actually substantially wider.


World Solar Challenge: solar cells

Part of the rule changes for the 2017 World Solar Challenge was a change to allowable solar cell array areas. In the Challenger class, the limits became 4 m2 for silicon and 2.64 m2 for multijunction gallium arsenide (in the Cruiser class, 5 m2 and 3.3 m2, which is the same ratio). Depending on the efficiencies of the two technologies, we therefore get the following comparison:

There are two important caveats, however. First, the cars in the World Solar Challenge will be getting pretty hot. The performance of multijunction GaAs degrades less with heat than that of silicon, so this increases the benefit for GaAs beyond that shown in the chart. For example, if we assume a 24%/35% efficiency combination for Si/GaAs, with temperature coefficients of power of 0.4%/0.2%, then the red dots in the chart show a GaAs advantage above about 43°C.

Secondly, the use of a 2.64 m2 GaAs array allows teams to build a smaller (and hence more aerodynamic) car, as Nuon and Punch have done. This increases the benefit for GaAs even further. Consequently, the five favourites (Nuon, Twente, Tokai, Michigan, and Punch) are all capable of winning the race, but the teams that switched to GaAs might have made a good move.

Update – the graph below clarifies the temperature-dependence for the two technologies (assuming a 24%/35% efficiency combination for Si/GaAs, and temperature coefficients of power of 0.4%/0.2%):


World Solar Challenge: the favourites

I will need to re-do this at some point, but the poster below shows the favourites (based purely on 2015 performance) for the 2017 World Solar Challenge (click to zoom). There is a very interesting mix of designs this year! For more details, see my annotated list of teams.


World Solar Challenge: doing media right

I’ve often pointed out that a solar car team is more like a startup company than anything else. A little like the early days of Google, really. The main product (the solar car, the search engine) is a gigantic money sink, and any cash coming in relates to something else (sponsorship, advertising). Overall success requires multiple skill sets working together. In particular, making sponsorship work requires an excellent media team (as well as a car fast enough to generate lots of good news). A number of teams have a track record of doing this well – Twente, for example, and Punch.


Deufol Technics packs Punch’s car and gear yesterday

An important example of sponsorship relates to transport. Here, the team acts as a kind of giant billboard for a tricky logistics problem handled well. This year, Punch provided a textbook example of superb media handling on this topic:

‘Voor mij is het de eerste keer dat ik voor zo een uitdaging sta,’ zegt logistiek manager Pieter Galle uit Leuven. ‘Het batterijpakket versturen is de grootste uitdaging voor het team. De batterijcellen die wij gebruiken zijn vaak niet toegelaten op vluchten. Om deze toch te kunnen versturen moeten er veel veiligheidsmaatregelen getroffen worden. Gelukkig heeft DHL Global Forwarding, in samenwerking met Deufol als verpakker van de goederen en batterijen alles tot in de puntjes kunnen regelen, zodat wij ons met het team volledig op het wereldkampioenschap konden concentreren.’” (Translation: “‘It’s the first time I’ve faced a challenge like this,’ says logistics manager Pieter Galle from Leuven. ‘Transporting the battery pack was the biggest challenge for the team. The batteries we use are often forbidden on flights. To be able to send them, many safety measures need to be taken. Fortunately, DHL Global Forwarding, in cooperation with Deufol our packer, has managed all the details, making it possible for us to focus our attention on the world championship.’”)

And Pieter Galle wasn’t just engaged in hyperbole there – transporting lithium battery packs really is tricky. In 2015, and again this year, there have been horror stories involving battery packs. I should also point out that some good photos really help the sponsorship game too, like these from Twente this year, or this one from Michigan, or this one from Nuon in 2015:


Nuon’s 2015 flightcase being loaded (photo: Jorrit Lousberg)

Another important sponsorship category relates to the team’s university. Here Western Sydney provides an excellent example, with their 2015 car being part of a major university rebranding exercise:


Western Sydney University’s 2015 car (photo: A. Dekker)

Michigan always does a great job of this during the American Solar Challenge. Their media team generates local news coverage everywhere they go. And the University of Michigan can afford to take the long view. If a 12-year-old boy or girl somewhere in rural America gets excited by the car, and decides to study engineering at Michigan one day, that’s a win. And not just for the university – if the sponsorship money keeps rolling in, the cars keep rolling on, and the fans can keep watching.


World Solar Challenge car sizes

The infographic above (click to zoom) shows the reported length and width of eight World Solar Challenge cars. The widest car (at 1.8 m) is that of the Swedish MDH Solar Team (although this car has large bites taken out of each side). The two family Cruisers from Eindhoven and Lodz (dashed lines) are also quite wide, and take full advantage of the maximum allowed length of 5 m.

The Belgian Punch Powertrain Solar Team has produced a very short zippy Challenger class car (illustrated), and Nuon’s car (not shown) seems of a similar size. In contrast, Michigan has a long narrow bullet car, powered by GaAs solar cells. Twente, using Si cells, has a substantially longer car than Punch, but a narrower one. It will be very interesting to see how these differences play out in the race, come October.