Yet another quick solar racing update

In recent solar car news, we have now seen new car reveals from several teams. The latest ones are shown above (click to zoom). Promised new car reveals include Vattenfall16 July, Michigan19 July, Stanford21 July, Aachen22 July, WSU7 August, Durham12 August, Cambridge15 August, EcoPhoton: some time in August, and JU30 August. I will continue updating my list of teams as news and pictures come in.

FSGP 2019 team photo – L to R from front: Kentucky, Illini, Esteban (Poly Montréal), W Mich / Florida, Principia, Calgary, SIUE / Northwestern, UPRM, Illinois St, Ga Tech / NCSU, Berkeley (CalSol), Mich St, Waterloo / NJIT, with Rutgers absent (credit)

Meanwhile, 18 teams – Kentucky, Florida, CalSol (1st in 2017), Northwestern, Mich St, Illinois St, Illini, Waterloo, Principia, Ga Tech, Esteban (3rd in 2017), SIUE, Calgary, Rutgers, NJIT, NCSU, W Mich, and UPRM – raced at FSGP 2019 on 1–6 July. Final results were as below (click to zoom):

The FSGP regulations give the score for multi-occupant vehicles (MOV) as S = (D / E) × C × T, where S is the total score, D is the Total Person-Mile Distance, E is the Total External Energy usage of the solar car, C is the Completion Factor, and T is the Target Speed Derate.

The chart below (click to zoom) visualises these scores on a logarithmic axis, with six coloured bars being components of the score, and the seventh coloured bar S being the product (and therefore the sum of the logarithms) of those components. The six components are:

  • d, the total miles driven
  • d, the total miles driven with penalties
  • p, the average number of persons in the car (and so D = d × p)
  • E, the total external energy usage (as in the regulations)
  • T, the target speed derate, which penalises cars slower than 27 mph (as in the regulations)
  • h, a grey bar (the same for every team) showing the highest driving distance of any MOV entry (and so C = d′ / h)

This version of the formula, S = d × d′ × p × (1/E) × T × (1/h), makes it clear that the distance driven is essentially being squared, and hence dominates the other factors:

It’s also worth mentioning the lap speed record that was set on the COTA track:


21 thoughts on “Yet another quick solar racing update

  1. The Belgian car looks absurdly small now that you see the team in the background!
    Stella looks even better than the previous one; and cool features indeed!

  2. Seems like Waterloo finally resolved the issues that they were facing, and are now on the track. Unfortunately it looks like North Carolina and Michigan State still haven’t passed scrutineering.

    Reading through one of the Waterloo team members’ blog, it seems like they dealt with a bunch of issues this competition. I guess that’s part of the challenge of bringing a team of mostly new members and an old car? The blog does give a pretty candid play-by-play of what the team was dealing with, since their social has been rather quiet. Reads for a pretty crazy day in the life! I can’t help but compare their performance to last year’s at ASC 2018, and am a little disappointed, as I was hoping to see more of their car on the track.

    Apparently, this year, they showed up in Austin with damaged brake discs (, and were scrambling to get new ones machined in time.

    On Day 2 (, they were unprepared to deal with an issue with their suspension, and then they managed to do some damage to their steering column during egress testing, as well as injure a team member with a hot glue gun.

    On Day 3 (, they were having BMS issues, which is surprising since from what I understand, the car they brought is the car that competed in ASC last year, with some improvements for reliability. This seemed to carry into Day 4 (, when they passed BPS scrutineering and moved onto Dynamics. However, the pins used to mount the motor to the wheel had sheered, and they didn’t have parts on hand to replace them. Moreover, they were still having issues with their brakes (they had issues passing Brakes test last year in 2018), despite having made changes to pass Brakes this time around.

    Yesterday (, it seems like their array wasn’t working after doing some reharnessing, and then somehow there was a short that resulted in the occupants egressing from the vehicle. And then while driving around, their motor air gap somehow closed, resulting in them needing to swap motors and reharness their SCM 150.

    • That’s a remarkably frank account of their problems (” I thought I was staying ahead of things as a manager but clearly that isn’t the case”). And the photographs are really good. Plus I learned a new phrase: “freedom units.”

    • Hey Jay, author of the blog here nearly a year later but thanks for reading and hopefully it gave some more insight into the things that were going on at the event. Personally curious, how did you end up finding the blog?

  3. June 19
    Average Speed
    The Target Average Speed for the Event is 35 miles per hour
    The Overall Average Speed will be computed as the total driving distance divided by the total elapsed time over the course of the event, in miles per hour.
    If a team’s Overall Average Speed is below the Target Average Speed, their score will be multiplied by

    July 3
    Target Speed Derate (T)
    V is the Target Average Speed which is 27 miles per hour for Formula Sun Grand Prix
    Va is the team’s Overall Average Speed which will be calculated as the average speed of all valid laps
    completed by the solar car over the course of the event, in miles per hour.
    If Va ≥ V then the target speed has been met and the Target Speed Derate will be calculated as:
    T = 1
    If Va < V then the target speed has not been met and the Target Speed Derate will be calculated as:
    T = 0.4(V-Va)

    The penny dropped.
    Anyone care to calculate a score under the June 19 regs?

    • Well 35 mph (56.3 km/h) is the ASC 2020 target speed (slightly higher than the 2018 value of 53.5 km/h). A 23% reduction for the FSGP track is quite reasonable. It seems that initially they just copied the ASC formula without that adjustment.

      As to scoring, the present scoring is dominates by the laps squared. Throwing in an exponential time factor could theoretically benefit fast cars that did few laps, but there were no such cars here, and changing the target speed would not have altered the ordering of MOV teams at all.

      More worrying is whether CalSol can manage to increase their average speed from 46.3 km/h to 75 km/h for BWSC.

      • Also, under this system a team could use a huge battery to increase the distance travelled knowing that it far outweighs the efficiency penalty, provided they travel furthest.
        Changing the target speed would not have changed the order, just given some ridiculously low numbers.

      • Re Calsol
        It would seem that, at this time, their battery is about 10kw/h short of the consensus.

      • The numbers would have been 0.313, 0.044, and 0.001.

        As to the battery, the ASC/FSGP formula effectively squares distance. If making your battery 4 times bigger doubles your speed, you come out even. Teams do have to make their battery big enough to manage the minimum speed, though.

        And yes, 15.876 kWH for CalSol seems like a small battery for BWSC.

  4. Except that, under these circumstances, where teams are only managing to run for about 50% of the event time, or less, they do not need to double their speed – only their range. So they might only need to double the battery size to come out way ahead of their opponents.

    • Possibly. I do agree that the days of small-battery Cruisers are at an end.

      I also have the feeling that, although the Cruiser Class was inspired by the BOcruiser, the “ideal car” for the class is now more like Lightyear One.

  5. They keep changing the rules so it’s hard to say but, yes, this year with the emphasis being almost entirely on range the Lightyear car could do well. If it was the only car to complete stage 2 – not at all unlikely – it would win.

    To me though the most interesting thing about the Lightyear car is that, despite being founded by EHV team members, they very quickly realised that the Stella model is NOT the way forward – yet. Whatever the achievements at a solar race, to be commercial a car has to look good and Stella simply does not fit that bill. None of the versions of Cruiser class scoring to date has sufficiently addressed that truth – therefore EHV keep winning.

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