Results of the ASC 2022 Road Race

Wrapping up the American Solar Challenge, the chart above shows the final official distances. The chart places optional “loops” driven at the end of each stage, even mid-stage loops. At the bottom of each bar is the final placing, with a star marking MOV (Cruiser) cars. The notation “(Tr)” identifies cars that trailered or were deemed to have trailered.

Below is a logarithmic visualisation of the MOV (Cruiser) scoring. The final score (last bar in each group) is the product (visually, the sum, since the chart uses logarithms) of seven factors:

  • The distance driven d (in miles)
  • The distance driven with penalties d’ (in miles)
  • The average number of people p in the car
  • The reciprocal of the total external energy usage E (in kWh)
  • The practicality score P (out of 100)
  • The speed derating T (1/70.86 = 0.014 for AppState)
  • In grey, the reciprocal h of 171,780 (the longest distance driven, times 100)

This is equivalent to the way that the scores are broken down officially (since C = d’/1717.8 and D = d×p).

The final score for AppState is 1/4.2 = 0.24, as in the official results. Esteban (Poly Montreal) achieved the highest score through low total external energy usage, but was demoted to third place after missing a turnoff early in the race, which prompted this retrospective modification to regulation 12.11.C:

“Any team leaving the tour route must rejoin the route at the same intersection where they left the route or they will be considered to have trailered from their last completed route step before going off route. Their Load On Trailer Time will be the time that they went off route.”

PrISUm (Iowa State University) was forced to withdraw early on due to electrical issues, so scores 4th in the MOV (Cruiser) class.

Challenges in the ASC 2022 Road Race

True to the name, there have been some challenges in the American Solar Challenge now taking place. On the first stage, Esteban (Poly Montreal) missed a turnoff, prompting this modification to regulation 12.11.C:

“Any team leaving the tour route must rejoin the route at the same intersection where they left the route or they will be considered to have trailered from their last completed route step before going off route. Their Load On Trailer Time will be the time that they went off route.”

PrISUm (Iowa State University) was forced to withdraw early on due to electrical issues

“Unfortunately things did no go as planned for PrISUm. Due to safety concerns for both the car and our team, we did not want to drive the car any farther. It is unfortunate that there was an electrical issue, which is hard to quickly and safely fix on race. We are very proud of our team performance at FSGP, compared to the last couple of years. Thank you to everyone for all of your support and following us throughout our journey.”

Canadian team Éclipse (ÉTS) had a major crisis on stage 2:

“On our 2nd loop in the city of Casper, our topshell detached from the vehicle; no injuries. The damage from this incident to the vehicle is not minor, but we worked very hard to get it back on the road! Thank you to all who helped!

Solar panels replaced, topshell corner redone in carbon fiber wet layup, tightened security attachments, lights picked up, stronger canopy, MPPTs repaired and even two flat tires all under 24h our convoy made it to time at stagepoint #2 in Lander, Wyoming just minutes from closing! The vehicle is in shape, today we are driving to Montpellier, Idaho.”

Illini (University of Illinois) had a narrow miss on the same stage:

“Today on our way to Lander, the team and Brizo faced a very near collision. As the convoy was waiting to turn left along the route, a semi lost control and tried to swerve around a pickup in front. The semi crashed a few feet from Brizo and the pickup truck landed mere inches from our chase car. Thankfully the entire team and Brizo were unharmed. However due to lost time, we had to trailer part of the second stage. Tonight we arrived in Lander and are ready for the rest of the American Solar Challenge.”

Official times for the first two stages are summarised in the chart below. The chart places optional “loops” driven at the end of each stage, even mid-stage loops. MIT leads the SOV/Challenger class, followed by Principia and Kentucky. The MOV/Cruiser scoring system is more complex, and only distances are shown here. However, Minnesota does appear to be ahead.

Latest news had most solar cars arriving at the Montpelier, Idaho checkpoint (including AppState and, I believe, Berkeley):

Follow the remainder of the race with the ASC car tracker (or just the dashboard). You can also check out the official ASC social media at        (click on the icons).

ASC 2022 Road Race Team Photo

Above is the official American Solar Challenge team photo (slightly cropped). From left to right, the teams are:

Stars (★) mark cars in the MOV (Cruiser) class.

Follow the race with the ASC car tracker (or just the dashboard). You can also check out the official ASC social media at        (click on the icons).

ASC 2021: road race, final day

Today sees the end of the American Solar Challenge. Above (click to zoom) are the final SOV standings, in New Mexico flag colours. MIT won, followed by Kentucky and Principia (Principia would have come second, were it not for some fairly stiff penalties given during scrutineering for minor regulation non-compliance).

Teams marked with a dot were forced to trailer at some point, and hence score lower. The optional “loops” driven are marked at the end of each stage (even the La Junta loop, which occurred in the middle of Stage 2). In the MOV class (not shown), Minnesota ran into problems, making App State the winners – their mountain-built car having taken all the passes in its stride.

Note: this chart reflect minor recent updates to the official Stage 2 numbers. The chart posted yesterday is therefore very slightly out of date.

The last day of the race was a short drive from Las Vegas, NM to Santa Fe, NM and back, across the Glorieta Pass through the Sangre de Cristo Mountains (easier than the Raton Pass). Above (click to zoom) is a day in the life of Illini according to the GPS tracker. Elevation data is from the tracker, so the elevation profile is slightly incorrect where the tracker cut out.

The chart above (click to zoom) shows MOV practicality scores. Black stars indicate final ASC placing (App State won the class). PrISUm did not qualify for the road race, but came third at FSGP.

Below (click to zoom) are some memories of the route (photos are from the ASC and the teams).

ASC 2021: one month to go

It is now just over a month until the start of scrutineering in the American Solar Challenge (27 July in Topeka, KS). I have updated my teams list with facts and pictures. As always, the documentation submission progress score gives an idea of which teams are in a good position (most of them, fortunately). A low score indicates that a team, considered as a socio-technical system, is operating in a highly stressed mode. In addition, if a team is building a car without official feedback on design documents, there is an increased chance of failing scrutineering (unless the team has considerable experience with prior ASC events).

There are 15 teams still registered for the race, although I do not expect the Egyptians to attend, and probably not the Taiwanese either. Of the remaining teams, 5 teams (Kentucky 3, Illinois State 17, Missouri S&T 42, Georgia Tech 49, and App State 828) will be racing veteran cars – although with various improvements – and the Brizo of Illini 22 is done. Of the 7 remaining teams building new cars, the Nimbus of MIT 4 is also done:

Nimbus on the track (credit)

In addition, PrISUm 9 have revealed their attractive-looking Cruiser Eliana:

The reveal of Eliana (credit)

Also, Principia 32 is making progress on their Ra XI :

Ra XI aerobody with vinyl wrap (credit)

Western Michigan 30 and Kansas 785 are also still busy with construction, the Freya I of UMNSVP 35 has a rolling chassis and aerobody, and North Carolina 99 is continuing their experiment of gutting a commercial ICE vehicle and turning it into a solar-powered Cruiser. Good luck, one and all!

ASC 37: Road Race Day 7

ASC, Day 7 (picture credits: 1, 2, 3, 4)

Day 7 of the American Solar Challenge was full of drama. An incredible race between Western Sydney and Michigan saw average speeds to the checkpoint in Mountain Home of 90.8 km/h (56.4 mph). In the Cruiser class, there was a tragic breakdown by Minnesota, which I think will leave Onda Solare the winners by default.

I am, however, giving my “Most Desirable Car Gem” award to PrISUm. Their car did not qualify for the road race, but I still think that their “solar SUV” is a fantastic concept.

And here are the night-time car positions (unreliable in the case of Michigan). I have overlaid them on my elevation map to emphasise the 850 metre downhill run into Mountain Home, and then the climb back up into Burns.

ASC 9: Aerodynamics

For both the Challenger class and the Cruiser class, solar car racing is to a large extent about aerodynamic drag. That’s overwhelmingly what the hard-earned solar energy is being wasted on, and therefore it’s what teams need to concentrate on minimising. The drag force on a car is given by the equation:

F = ½ Cd A ρ v2

Breaking that down, v is the speed of the car, ρ is the density of air (about 1.2), A is the frontal area of the car, and Cd is the drag coefficient, a number which indicates how aerodynamic (and therefore, how energy-efficient) the shape of the car is. For Challengers, minimising Cd allows the speed v to be increased, while for Cruisers (for which the average v is essentially given), minimising Cd allows non-solar energy use to be minimised. Of course, minimising frontal area is important too (and that is the motivation behind asymmetric Challenger cars).

To give a feeling for the all-important Cd, here are some vehicles with values ranging from 0.19 to 0.57:

Drag coefficients for a selection of vehicles. Clockwise from top left: 0.57 – Hummer H2 (photo: Thomas Doerfer); 0.30 – Saab 92 (photo: “Liftarn”); 0.26 – BMW i8 (photo: “youkeys”); 0.19 – General Motors EV1 (photo: Rick Rowen)

Because Cd is so all-important, it is the one thing that solar car teams are really secretive about. Challengers generally have values under 0.1. With no need for practicality, they chase their way towards the impossible goal of Cd = 0, trying to come up with the perfect race car, which will slice through air like a hot knife through butter:

Nuon’s 2005 car, Nuna 3, with Cd = 0.07 (photo: Hans-Peter van Velthoven)

Cruisers, on the other hand, have to balance aerodynamics with practicality. Bochum’s early SolarWorld GT had Cd = 0.137:

Bochum’s 2011 car, SolarWorld GT, with Cd = 0.137 (photo: “SolarLabor”)

Eindhoven’s recent Stella Vie, with its sleek aerodynamic shape, does much better than that (but they won’t say how much better):

Eindhoven’s 2017 car, Stella Vie (photo: TU Eindhoven, Bart van Overbeeke)

I understand that Sunswift’s 2013–2015 car eVe had Cd = 0.16. Appalachian State (Sunergy) have stated that their newly-built ROSE has Cd = 0.17. PrISUm’s Penumbra has a higher value (Cd = 0.2), because of the blunt end which they chose for practicality reasons (although they did do a few clever things to reduce the impact of that blunt end). I’m not aware of the Cd values for other ASC cars.

Appalachian State’s beautiful ROSE, with Cd = 0.17 (image credit)

ASC 8: About Cruiser Practicality

The American Solar Challenge Cruiser class is a contest for multi-person solar vehicles, each powered by 5 square metres of silicon solar cells (or 3.3 m2 of multi-junction cells), with the option of recharging from the grid. The contest is not actually a race – cars must get to the finish line on time, carrying as many people as possible, and drawing as little power from the grid as possible.

Cars are also scored partly on practicality. This can mean different things. Eindhoven’s 2015 car (Stella Lux), for example, was designed as a four-person family car, and the team took photos of it doing family things like shopping, going on holiday, and picking children up from school. A big feature was that, for an average family in the Netherlands, the car would produce more electricity than it used. The car scored 84.5 for practicality at the 2015 World Solar Challenge.

Eindhoven’s Stella Lux (photos: TU Eindhoven, Bart van Overbeeke 1, 2, 3, 4 – click to zoom)

Bochum’s 2015 car (ThyssenKrupp SunRiser), on the other hand, was a luxury two-person sports car, with leather seats and an incredibly beautiful interior. It was an almost perfect example of the car it was trying to be, and scored 80.5 for practicality (far higher than the next car, which scored 63.5).

Bochum’s ThyssenKrupp SunRiser (photo: Anthony Dekker)

One of the highest WSC 2017 Cruiser practicality scores went to PrISUm for their four-seat Penumbra, which was intended as the kind of practical SUV that you might take on a fishing trip. The car has plenty of room for carrying your esky, tackle box, etc. PrISUm deliberately made some aerodynamic compromises in order to achieve their practicality goal, and the car scored 79.8 for practicality at WSC 2017.

PrISUm’s Penumbra (composite image)

This year at ASC, PrISUm’s Penumbra is again a strong contender. Minnesota (UMNSVP), Appalachian State (Sunergy), and Waterloo (Midnight Sun) are entering two-person solar sports cars, while Onda Solare from Italy seems to be inspired by Eindhoven (see my annotated teams list). It promises to be an interesting field.

Midwestern Solar Challenge

On June 3, two of the top Cruiser-class solar cars held a Midwestern Solar Challenge, racing south from St Paul, MN to Ames, IA. The teams were:

Race news


Here is my (totally informal) scoring of the race (see the chart below):

  • Person-kilometres is the race distance times the average number of people carried (which I believe was 4 for PrISUm and 2 for UMNSVP). The first coloured bar shows this, scaled so that 100% is the highest value.
  • Energy input is the number of charges (1, in this case) times battery size. The second coloured bar shows this, scaled so that 100% is the highest value (this bar points downward, because smaller is better).
  • The third coloured bar shows the ratio of these numbers, scaled so that 80% is the highest ratio.
  • We add on (in grey) the practicality scores (I’m estimating 9 for PrISUm and 7 for UMNSVP), scaled so that 20% is the highest practicality.
  • This gives final scores of 100 for PrISUm and 82 for UMNSVP. Congratulations, PrISUm!
  • But will PrISUm still have the advantage when it needs to carry passengers uphill?

Solar Car Racing Status Check

In solar car racing news, preparations are beginning for the SASOL Solar Challenge in South Africa (September 22 to 30). It seems that both Nuon and Tokai will attend this event, along with local teams.

Nuon at WSC 2017 (photo: Anthony Dekker)

Thirteen teams have registered so far for the 24 hour iLumen European Solar Challenge 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  

Twente at WSC 2017 (photo: Anthony Dekker)

The American Solar Challenge is a lot closer than those two races, with scrutineering beginning on July 6, track racing on July 10, and the road race running from July 14 to July 22. I am maintaining a detailed information page and teams list for this race. At last count, 34 teams were registered, with Anderson, UCSD, Principia, UC Irvine, Phoenix, and UT Austin having, sadly, dropped out.

Six teams are attending with cars that raced at WSC 2017, although these cars will require adjustment to satisfy ASC rules (Michigan, Western Sydney, Principia, and Illini, plus the Cruisers PrISUm and Minnesota). Six other teams are attending with cars that previously raced at ASC.

PrISUm at WSC 2017 (photo: Anthony Dekker)

Twenty-two other teams are frantically building cars for ASC. Car unveils that have been announced include team 42 (Missouri) on 18 April, team 55 (Esteban) on 23 April, team 101 (Eclipse) in mid May, team 828 (AppState) in mid June, and team 65 (Calgary) on 16 June.

Missouri’s unfinished car (picture credit)

See my detailed information page and teams list for this race for more information and for social media links. I will continue to update that page as news comes in.