World Solar Challenge: How Far In A Solar Car?

Solar power is a great source of renewable energy, but has always had its limitations. At best, there’s only 1,000 Watts/m2 available at the Earth’s surface on a sunny day, and the limited efficiency of solar panels cuts this down further. It’s such a low amount that solar panels on passenger cars have been limited to menial tasks such as battery tending and running low-power ventilation fans.

However, where some might see an impossibility, others see opportunity. The World Solar Challenge is a competition that has aimed to show the true potential of solar powered transport. Now 30 years since its inception, what used to be impossible is in fact achieved by multiple teams in under one tenth of the original time. To keep competitors on their toes, the rules have been evolving over time, always pushing the boundaries of what’s possible simply with sunlight. This isn’t mainstream transportation; this is an engineering challenge. How far can you go in a solar car?


The Quiet Achiever, pictured here on its 1982 cross-continental journey, was the progenitor of the World Solar Challenge.

The progenitor of the event was one Hans Tholstrup, a Danish-born adventurer with a passion for sustainability and alternatives to fossil fuels. Working with Australian touring car legend Larry Perkins and his brother Garry, the trio built a solar-powered vehicle named The Quiet Achiever.Β In 1982, the lightweight vehicle travelled 2518 miles from Perth to Sydney in just 20 days, solely under power from the sun. The feat received much public attention, directly leading to the first running of the World Solar Challenge just 5 years later.

The inaugural competition was put together in 1987, in partnership with the South Australian Tourism Commission. It saw 13 competitors line up at the start, with 6 reaching the finish line. General Motors won the event with Sunraycer, completing a course from Darwin to Adelaide in just 44 hours 90 minutes, beating the second placed entry from Ford Australia by almost 23 hours.

Initially happening every three years, it switched to every two years from the 1999 running. Some years have seen over 50 teams join the race at the start line, though many drop out due to crashes or mechanical issues bringing their race to an end. Entrants come from diverse backgrounds all over the world to compete in the race. The last three decades of competition has seen entrants from automotive manufacturers, technology companies, universities and even high schools. Often, team sponsors come from high-tech industries involved in technology relevant to such applications.Β  Having a company onboard that can supply highly efficient solar panels or a lightweight, powerful motor can go a long way.

The race is run from Darwin in the Northern Territory, down to Adelaide in South Australia. The race finishes with all competitors forming up in Victoria Square for final celebrations.

Over the years, the race has evolved as new technologies have come to the fore. Regulations on maximum solar panel area have tightened as panels have become more efficient over the years. This helps to keep costs down, as the latest and greatest solar panels don’t come cheap. Other regulations focus on limiting onboard energy storage and ensuring a level playing field among competitors. Competition vehicles run on public roads and thus are required to abide by speed limits and road rules.

As average speeds have increased over the years, the rules have changed to place a focus on practicality as well, aiming to guide competitors towards designing vehicles that are closer to something usable on the street. The competition now features the Cruiser Class for multi-passenger vehicles, which are graded on factors such as ease of ingress and total number of passenger-kilometers racked up over the journey.

It’s All About Efficiency

The Tokai Challenger, built by students from Japan Tokai University, won the 2009 event. Note the extreme, streamlined design aiming to minimise drag.

Much like traditional motorsports, the regulations of the World Solar Challenge have shaped the designs of competition vehicles. With limited energy available, efficiency is key in every aspect of design. A competitor that is able to capture the most energy and turn it into forward motion is best placed to bring home the win.

On the electrical side, the first concern is effectively capturing as much energy from the available sunlight as possible. Installing the highest-efficiency solar panels available is just one part of the equation. Teams will often tilt their solar panels to be perpendicular to the sun’s rays after driving ends at 5:00 PM, to make the most of the light available before sundown. To wring every last drop out of the cells, Maximum Power Point Tracking hardware is used to keep the solar cells in their optimum operating range. Motors and controllers are similarly designed with a focus on wasting as little power as possible when propelling the vehicle down the road.

2013 saw the introduction of the Cruiser class, for solar vehicles intended to carry multiple passengers.

Perhaps the biggest impact on the external design of these vehicles is aerodynamics. Travelling at speeds of up to 130 km/h for hours at a time, drag plays a huge role in terms of energy efficiency. Reducing drag to the absolute minimum is key, with vehicles in the single-occupant Challenge class often featuring swooping, knife-blade teardrop designs. Wheels are often fitted with airfoil-shaped fairings to allow them to slice through the air. Historically, most designs had drivers laying in near-prone or recumbent positions to minimise their contribution to the profile of the car, however in recent years, seating positions have been changed to a more natural upright position to better resemble a road-going vehicle. Entries in the Cruiser class tend to have more compromised designs in this area, as they are necessarily bulkier and taller in order to carry multiple seated passengers. However, they still aim to minimise drag wherever possible, even if knife-edge streamlined designs aren’t practical in this class.

Mechanical efficiency is also key in order to build a competitive vehicle. Rolling resistance must be kept to a minimum, and specially designed tyres are used in pursuit of this goal. It’s also important to ensure bearings, chains and belts are properly chosen and maintained to avoid excessive losses in these areas. Attention to such small details can have a serious impact when travelling thousands of miles, particularly when such low amounts of energy are available.

Looking To The Future

As teams continue to build cars to best the existing challenges, the ruleset continues to shift to push the limits further. For 2021, regulations will again change to focus on driver comfort, dynamic stability of competition vehicles, and include new safety features like daytime running lamps. All of these changes have an effect on performance, from changing aerodynamics to adding a new power draw to the vehicles. However, it is this very challenge that forces teams to innovate and adapt their designs, creating better and more capable solar cars than ever before. While we don’t expect solar panels to become standard on passenger vehicles any time soon, barring a major change to our Sun, the event nonetheless serves as a useful showcase and proving ground for the very best in solar and electrical propulsion technologies.

90 thoughts on “World Solar Challenge: How Far In A Solar Car?

  1. Great article. I was in Australia for the 2013 World Solar Challenge, and that was easily the craziest adventure I’ve ever been on. Today almost all entrants are from colleges and universities, so a big part of it is the learning experience for those involved.

      1. It is regular if infrequent, unless you like to indulge in climate hysteria and attribute the current state of the system to something else and imply that the current state will become more frequent in its occurrence.

  2. The solar challenge suffers from the same flaw as the Shell Eco Marathon, which is that the teams take advantage of every loophole in the rules and use increasingly esoteric optimizations that have nothing to do with practical road-going vehicles.

    For example, the passenger-kilometer rule is gamed by having a support vehicle trailing behind and carrying a number of people, such that when the wind turns favorable and the sun is up, the competition vehicle is loaded up with people to rack up more passenger-kilometers – and then when the sun starts to go down and/or the winds turn headwise, they unload people back to the trailing vehicle to reduce the rolling resistance.

    1. For the sake of the competition of course, this is not a problem because the rule is the same for everyone – but then the teams, or the sponsors and companies behind the teams, come out to advertise these vehicles as something revolutionary because they’ve done so well in the Solar Challenge.

      The Holland team (Stella Vie) for example is trying to sell the concept of their car as an actual road-going vehicle that could charge itself AND other cars, which is plainly ridiculous since it is unlikely to even charge itself in the central/norther European climates, and its road safety is dubious because it’s basically a rigid light frame on four skinny motorcycle wheels, which is better fit in the quadricycle category than an actual car (L6e or L7e depending on mass).

      And I think this is just a scam. I mean come on, who are you kidding really – you know the car doesn’t actually work, except under the scorching sunshine of outback Australia. When it’s winter in the Netherlands, you can’t ditch passengers and cargo when you’re running low on power, and keeping the car in a parking garage or under the shade of a tree or a building, it obviously gets no sun.

      1. I woul actually like these to be available to buy. They could be cheap because so little material is used. And for the Netherlands or Europe winter in general, i found out those nice cheap 48-80V “range extenders” with GX-fake-160 engines and 2-8kW of power output. Just hide one inside (as a cargo, of course) and off you go with ridiculous fuel efficiency.

        1. I don’t know if it’s any cheaper, since they use expensive materials like carbon fiber in a single shell frame which is not easy to manufacture.

          If it was ordinary welded sheet steel, it would be a different matter, but this is extremely optimized for weight so it has to employ exotic measures that do not lend themselves easily to mass-manufacturing.

        2. Hydraulic hybrids get no love nor research grants despite having been around for decades.

          Like a 2nd generation Prius but with a pressurized air tank pushing hydraulic fluid in and out instead of a battery and electricity. Unlike the battery the tanks and fluid don’t wear out and ‘recharging’ happens as fast as the fluid can be moved.

          Too bad they didn’t get a Bradley GT II body instead of the original Bradley GT. The original, while obviously having far less drag than a VW Beetle, is downright ugly. The GT II design, 45 years old now, looks like something that could be rolling off a line in 2020. The original GT looks like exactly what it is, a typical ‘sporty car’ design from 50 years ago, sculpted by someone who thought he knew what he was doing when it came to design. For some reason the company managed to sell around 6000 bare bodies, kits, and completed cars in 11 years while the better looking, better designed, *better in every way* GT II only sold around 500. Perhaps the GT should have been discontinued and all those resources put into increasing production and lowering the cost of the GT II?

    2. “teams take advantage of every loophole in the rules and use increasingly esoteric optimizations that have nothing to do with practical road-going vehicles.”

      Don’t you think that if they wanted the competition to be about “practical road-going vehicles” then they would have put that in the rules? This is an academic challenge, don’t mistake it for anything else.

      1. Sure, that’s not the problem I have. The comment moderation system just ate my other reply where I explained the point – maybe it will turn up a week later.

        Basically, some of the teams or their backers are going around literally selling these concepts as the next best thing since sliced bread and that’s not OK. That’s misleading.

    3. That is effectively outright cheating. The passengers should be in from the beginning to the end and should have the A/C going as well or windows rolled down. Otherwise it’s just a glorified toy car competition.

      1. No it’s not cheating. It is within the rules – and that’s the point I was making. The public thinks these are great strides towards solar mobility, but in reality it’s just winning by numbers.

    4. Of course, just about any motor racing tends to have creative, bizarre, tortured, or comical interpretations of the rules. One of the more famous examples was a drag racing class where they were trying to keep the cars in the class looking like street cars, so they specified a minimum windshield area to keep racers from lowering the roof line too much. One team showed up with a windshield that was the required area… installed nearly horizontal.

      1. Heh, figures.

        In the same vein, when Volkswagen showcased the 1 liter concept car ( XL1 prototype), they did so in Saudi Arabia. Why? Because when you’re running the car in 40 C desert heat, the air resistance is significantly lower due to lower density.

          1. I was thinking of the 2 seater, and if it really had gotten 300 mpg I wouldn’t care if it ran off of gasoline, kerosene, diesel, charcoal briquets, or sunflower oil.

          2. If you want one you can probably build one – the technology is fairly old now and as another commenter said it’s basically achieved by compromising everything else you might actually want out of a car.

            Or just buy something that’s already ridiculously light and unsafe like a Citroen 2CV or original Mini and swap the motor out for a tiny lightweight modern diesel – those cars got modern MPG with 60+ year old engine designs (carbs + points) so you should be able to crack 100MPG very easily if you’re willing to drive at the speeds your great grandfather did.

          3. Well, it if would get even close to 300 MPG I’m sure it would be of some use.

            But then again you can buy a diesel Royal Enfield motorcycle and get about the same mileage – with just as much comfort. They’re quite popular in rural India. As a curiosity, you select your speed by the gears – the throttle position has very little effect on the engine speed.

          4. Quick calculation on the diesel Enfield tuns up 200 MPG or 85 km/L although real-world mileage tended to be closer to 150 MPG in US gallons. They were made up until 2000.

            Just goes to show that it’s not impossible to get low energy consumption, but doing so sacrifices a lot.

        1. Maybe Volkswagen showcased the L1 in Saudi Arabia, but it certainly used it in Europe as well. VW CEO Ferdinand Piech traveled from Wolfsburg (VW headquarters) to Hamburg at an average speed of 72β€―km/h (45β€―mph) and a top speed of 120β€―km/h (75β€―mph), needing just 0.89β€―l/100km (264β€―mpg).

          Such cars are undoubtedly usable in day to day travel for average people. Just not built in quantities, because for the same money one would also get a 4-seater (with 5 times higher fuel consumption).

          1. The keyword is consistency. Using hypermiling techniques, you can increase your mileage by 30-50% in just about any vehicle. Add in favorable weather conditions and you’re set. However, this does not reflect real-world day-to-day driving.

            The reason for the Saudi Arabia showcase was just that. They picked the most favorable conditions to make sure it performs as advertised. This is also why even under the WLTP fuel consumption tests, the automakers can cheat, such as disconnecting the alternator and taping over the door gaps to get the absolute best test mileage.

      2. Or, do you remember the hoover cars? The Chaparral 2J and the one F1 car (Brabham BT46B) that used fans to suck the car down onto the road? There’s legends about cars that could stick to the ceiling of a tunnel, but these cars did produce 1.5 G of downforce even at moderate speeds. The 2J had a separate two-stroke engine just to run the fans at full blast all the time.

          1. That’s nice, but the airflow generated by the twin 17 inch fans of the Chaparral 2J would push the car along at up to 40 mph by themselves, and the car could in theory stick to a ceiling at standstill.

          2. Of course the 55 BHP two-stroke engine that was running the fans was never designed to operate upside down.

            What’s curious is that they weren’t banned because of the fans, but because they were using an adjustable skirt that sealed the car to the road. That violated the movable aerodynamic feature rule.

      3. That’s when the first streamliner bodied funny car rolled up to the line at an NHRA event, the organizers should have said “Get that out of here!” and banned it. Now they all are streamliners and if the bodies aren’t all identical they’re very close to it.

        Then Kalitta got killed running off the end of a track and the NHRA says “We need to slow the cars down. Let’s shorten the race to 1,000 feet.” The answer should have been *ban streamliners*!

        Revise the funny car rules so that a body from the base of the windshield aft and the centerline of the front wheels fore must be identical in size and shape to a stock vehicle. Stretching only allowed between the base of the windshield and centerline of the front wheels. Side skirts must extend straight down from the lowest part of the rocker panels, front fenders, and body. Skirts may be flared out starting 12″ ahead of the stock lower forward point of the rear wheel arch. Air dams, chin spoilers and other aerodynamic devices allowed ahead of the front wheels, from the farthest forward part of the stock front bumper down. All the size, height etc currently done rear spoilers should be allowed, as long as it’s mounted on top of the stock body shape and is removable for LASER scan shape verification. (NASCAR now LASER scans instead of using physical templates.) Body alterations to the rear quarters allowed to accommodate the big tires but must not involve the stock door panel areas or the rear bumper or trunk lid. All stock opening body panels’ lines must be molded into the body. No limit on how high the rear of the body can be lifted to allow for rear tire size and expansion, though going to an excessive amount over what’s actually needed should be avoided. Lifting the rear gives more downforce but slows the car down so that ought to be self limiting without a niggling nitpicky rule difficult to measure for due to the variability in tire expansion. Last thing, a limited angle range for the rear panel of the rear spoiler when the car is at rest without fuel and driver.

        Those rules ought to safely slow down funny cars by forcing them to punch bigger, rougher holes in the air. Cut up a stock metal body, mock up the allowed alterations, then make a mold and lay up one piece funny car bodies.

        For slowing down Top Fuel. No more slick closed cockpits. Tall windshields with a strong top edge and a metal grille to protect against ingress of car parts or track features in a crash, but make it produce drag. Ban any body extension or other device that shields the rear wheels from or otherwise diverts air over or beside them. The exhaust from a Top Fuel engine can produce 800~1,000 pounds of downforce. If the pipes are allowed to be angled aft any amount, stop allowing it. They should have no rearward angle at all with the vehicle at rest without fuel and driver so the exhaust force will contribute nothing to acceleration. Then when the car takes off and the tires are at maximum expansion, the exhaust will tilt slightly forward, providing some additional amount of resistance.

    5. You could make a similar criticism of Formula 1, should we not bother with that, either? Or Pikes Peak, or, while we’re at it, the Tour de France or the Americas Cup? There are many races which need back up, doesn’t make them worthless.

      1. Yes, but those races don’t pretend to be solving the world’s transportation woes. Pikes Peak is just about getting to the top of a mountain really fast, because it’s a challenge. It was never about pushing the envelope for road-going vehicles.

        You might make the criticism about the Formula E series, which some people say is pushing the envelope for electric cars – but what’s really happening is that the teams just buy what’s already available on the market and optimize that for racing, within the limitations of what they’re allowed to have. They’re not allowed to do anything that isn’t available to every other team, so no independent R&D is really possible and the point is lost.

        1. Every kind of racing should have an unlimited anything goes class to push the state of the art. If people get hurt or killed participating, well, nobody forced them to!

          But every time some “outlaw” class gets started up it either dies off from some people whining about how “unfair” things are or the whiners get into power positions in the organizing group and start putting in rules and restrictions until the “outlaw” class is pretty much identical to some other class, and it dies off because there’s no point to it anymore.

          Same thing happens when someone starts up an affordable class with few but very exacting rules about what is and isn’t allowed, intended so that anyone can easily and affordably participate with stock, off the shelf equipment with a few minor alterations allowed or required for safety and performance.

          People cheat and threaten to quit and take all their friends with them if their rule bending isn’t allowed, so the cheat gets put into the rules. Repeat and repeat until only people with multiple millions of dollars in corporate sponsorship can participate.

          That’s how NASCAR *began* in 1948 but by around 1951 the rules were being severely bent and broken and instead of Bill France putting his foot down and saying “NO!” to all of them, he started putting the cheats into the rule book – and the result is the crap NASCAR has become today.

          There was a “supercar” racing series in Europe in the 80’s and 90’s that began like NASCAR. The cars had to be built from a factory stock vehicle with very limited alterations allowed. By the time the series was disbanded they still had to start with a stock body but had allowed so many changes all that would be left was part of the outer skin on a metal tube and carbon fiber panel frame, with massive flared fenders which were sliced up into a large number of stacked winglets and you could see *through the car* when looking at the side. If only someone had said “NO!” and kept saying it whenever someone showed up with a not allowed modification from stock.

  3. While it’s a great challenge and will no doubt spur innovation that can be put to practical use the fact is we will never have purely solar cars, there is a reason plants don’t run around.

    1. Though granted, plants have an energy conversion ratio an order of magnitude worse than solar panels. They’ve evolved to survive on the minimum available power, not the average or the peak, so they toss away quite a lot of what they could collect.

      1. Yes plants aren’t as efficient but still moving a car purely on solar is still beyond us, topping a car up sure, but it still needs energy storage.

        “If the solar panels are very cheap, it makes all the sense in the world because it reduces the overall energy consumption of the car by about 10-20% depending on use and location, but in no way are you going to drive the car solely on solar power.”

        What he said.

        1. There’s two ways to go about it. You can use the peak available power, which gets you around fast but not reliably, or you can use the minimum available power which always gets you as far as it does, slowly.

          A regular car uses about 20 kW of power to get along. A person walking uses about 200 Watts of power. In order to make a solar powered car that can go whenever you want to go, you need a vehicle that can essentially be pulled along by a person walking. Essentially, a hand cart rickshaw.

          1. While I agree with your math, I don’t entirely agree with the conclusion. I have a power meter on my bike, and produce about 215 watts continuously for an hour. (More for shorter periods, slightly less for much longer periods.) 215 watts is enough that I average 34km/h on my 80 minute long commute to work, and that’s including stopping for stoplights.
            I’m not claiming that’s fast. But for a lot of people who live in cities, average commute speed is lower than that. It wouldn’t take a lot of battery, combined with one square meter of solar panel, to cover that use case. I’m not claiming this is even remotely useful for a family car if you have kids and need to haul building materials for house repair sometimes. But for some situations, 200W is might be marginally usable.

          2. > 80 minute long commute to work

            See, that’s already a dealbreaker for about 99% of the population. The rest is irrelevant.

            >average commute speed is lower than that.

            It’s not, and if you’re sitting 80 minutes in any sort of a car, you’ll be spending a least 1 kW just running the AC to keep you from sweating up your good shirt. Alternatively, for running the heater so your windows don’t frost up.

            The bicycle is not comparable to a car because you have different assumptions, like being able to take a shower and a change of clothes when you get to work.

          3. I’m with smelly here – even though your maths is reasonable you forget two things
            – That many vehicles drive for 20mins maybe an hour then sit for an entire workday before going back again. A great many cars don’t move for days as well – those folks that usually walk as they work local etc. So a usefully solar powered car doesn’t need to be as you describe at all if it has any onboard energy stores.
            – even for sustained driving you can easily fit onto a normal white van size vehicle a potential 2Kw (more even with some redesign in the body shape of ‘peak’ solar – so even if you assume its poorly orientated and a bit cloudly at the moment you still have more than 200 watts available based on the performance % of my own solar installation in a usually cloudy England I’d say double that is a fairer ballpark (yes it can be worse, but I rarely see a day bad enough to get such a really low percentage of the peak (at least if you only count the hours the sun is actually up – on the short days with 24 hour average you certainly are on the money – perhaps even generous at 200w)).

            You also exaggerate a little – 20kw is pretty high for ‘getting along’ power, perhaps about right for higher speed motorway type cruising but on the slower roads 5Kw might well be enough – heck some cars have less than 20KW maximum power – but this is going to vary by size, shape, weight and speed a fair bit).

    2. We don’t drive around in F1 racing cars either, but there are plenty of technologies developed for it that have made their way into consumer vehicles.

      A solar car isn’t just the solar panels, it’s the battery storage and electrical drive train as well, and those have huge potential for improving conventional EVs.

      1. In a roundabout way, yes, but mostly you have a parallel development somewhere else that is actually responsible for the technology. They just claim credit when it becomes popular enough. Some of the most egregious claims I’ve head is that the reason you have a magnet inside your heater boiler to collect iron particles is because Formula 1 cars use one in the oil filter – but the invention is obvious and trivial.

        Can you name one technology in F1 that’s actually original and saw widespread use because of it?

        1. – Active suspension
          – Sequential gearboxes
          – Steel Disc Brakes (not actually in F1 but Le Mans)

          And I’m sure that other things like tyres, aerodynamics and engines took a lot of the development on the F1 to the everyday cars.

          1. Active suspension: first developed by CitroΓ«n in 1954. Not from F1.

            Sequential gearbox: 1946 Porsche Type 360, Cisitalia Grand Prix. Not F1.

            Steel disc brakes, not F1 as you said.

            I rest my case. The point is that the technologies have parallel development outside of the F1 circuits, which is actually necessary because the same technology as applied to F1 cars cannot work in a street car as-is. Many solutions can work in a race car that will simply not do in a street car.

          1. Disc brakes are an ancient invention dating back to 1890’s.

            Coilover springs date back at least to the McPherson suspension system which pre-dates F1, and to airplane landing gear suspension systems developed by Fiat in the 1920’s.

    3. Somebody’s currently trying to resurrect the Aptera design and added solar panels; they’re claiming it gets 45 miles per day off the solar power if you can give it full sun all day. Longer distances require plugging it in to charge its batteries. It remains to be seen if they can actually get this into production.

  4. This seems like an inefficient and unreliable application/goal for solar. Just like with most solar powered loads/applications, you only use the load a fraction of the sun-producing day. However, solar doesn’t give you much live constant output of current. This is why every solar setup involves either a battery to store juice collected throughout the day (off-cabin grid, RV, etc.) or backfeed AC power to the grid, where someone else on the grid will consume the power (and you get paid for the little bit of power you fed to the grid).

    You wouldn’t put solar on your off-grid house with no means of storing power – you wouldn’t have any power to use at night, and even during the day you wouldn’t be able to run certain high current but short use duration items. With proper battery setup in the mix, your constraints loosen up a bit – you simply need to consume less power per day than your PV panels produce per day.

    With a car it makes even less sense – you’re not properly angling the panels at the sun because itd be really awkward to do every time your car changed orientation, and you would constantly be in shadows if you drive anywhere except desert highways. Itd be a lot more efficient to have distributed solar farms and use that power to recharge EV batteries. This is how solar is done (and any other renewable energy source that gives a low but somewhat constant output).

    1. That’s why the solar challenge vehicles are allowed a set amount of batteries and charging per day of travel.

      For a car parked outside under clear skies, you have a potential to get about 5 km free per day on average. That’s assuming 2 square meters of panel at 15% efficiency and 15% capacity factor. This makes for about 45 Watts and 1080 Wh per average day, divided by 200 Wh/km which is typical for a small hatchback like a Nissan Leaf.

      If the solar panels are very cheap, it makes all the sense in the world because it reduces the overall energy consumption of the car by about 10-20% depending on use and location, but in no way are you going to drive the car solely on solar power.

      1. You’re right about solar challenge vehicles – they’re built as competition cars and would be pretty lousy in real-world scenarios. The Cruiser class cars are judged on “practicality”, so they make all sorts of claims about their usefulness that really only hold up in comparison to other solar cars. Most teams realize that there is no marketability for any of their cars.

        That said, solar panels are indeed very cheap, and Sono Motors is doing exactly what you’re describing. They claim 20 miles/day of charging (presumably under ideal circumstances). Not that I’m expecting that idea to take off, but it’s worth mentioning.

        1. Then again, when you leave your car out in the sun to charge and take off, you’ll need the power collected by the solar panels simply to run the AC to make the car tolerable to sit in.

          80% of the energy goes right past the panels and heats up the car.

        2. All good points Dude & Peter. Obviously this is a challenge, and a cool challenge at that – so on that note I shouldn’t be whining about how the end objective isn’t the most practical for real life. After all, revolutionary innovation doesn’t come from saying “the way we currently do things is best, so lets just work on incrementally optimizing the way we currently do things”.

          That being said, I think the following two constraints are major blocks in a truly “off grid” car ever being remotely as practical as plug-in EVs with tech that’s already decades old.
          1) PV panels size is limited to that of the footprint of the car. This immediately puts a cap on your daily budget of power to work with.
          2) It is difficult to angle the PV panels so they are directly normal to the sun’s rays when the vehicle is constantly changing orientation & pitch while driving. This leads to just mounting them “flat”, where you’ll get reduced but equal performance from all cells, or mounting them on a curved surface, so that some cells are aimed optimally and others are making zero power – either way you get the same result of incredibly low efficiency solar (like 40%-60% the overall power compared to mounting the same cells on a roof where they are fixed at the most ideal angle and orientation.)

          My point is that overall, it would make more sense to have PV panels in fixed land based locations. Although you absolutely lose power & efficiency transmitting and distributing power to where it needs to go, as well as storing power so there’s reserves to use at night – the overall efficiency and lack of constraints are greatly improved by sticking with land-based PV panels collecting and transferring power to battery EV cars as needed (and that still counts as powering cars with solar power!).

          1. Then there’s the factor that a car should last for 20 odd years, so the solar panels must take all sorts of dings and bangs, road salt, being blasted by dust, rocks… and they can’t have a thick protective glass on top because that would weigh a ton. Instead they’re thin film panels that are laminated under a clear coat of polyurethane paint, which offers little protection from physical damage.

            All you need is a single hailstone in the right spot and the panel is dead, and then you have to replace the entire roof of the car, which is a structural member, which means your car is now broken.

          2. Forgot to specify: the solar panel would be laminated onto a carbon or glass fiber composite chassis which is made in one piece to be extremely light. If the solar panel breaks, the whole thing is junk.

  5. Darwin to Adelaide’s Victoria Square? I guess McLaren (sp?) Vale got tired of being invaded every year. In the 1990 WSC, there were vehicles managing 45-60mph, running for 8 hrs a day, and drawing 50% of the power required directly of their arrays.

      1. I’m not. I’m complaining about the hype that surrounds this competition, just like with all similar competitions that actually have nothing to do with sustainability or green transportation any more than box car racing does.

    1. What is the “sustainability” of a thing that has no practical application?

      That’s called greenwashing. It’s harmful for the entire cause to pretend that technologies that are mostly but a bag of tricks have anything to do with sustainability, because it’s creating the illusion that we have all this figured out and saving the world is just a matter of making more hocus pocus.

      This is an endemic problem in the society. For example, we have a plastics problem; people say, “Let’s recycle plastics. There, problem solved!”, and then it turns out you can only recycle about 10% of it and even doing that much still takes tremendous amounts of other resources. The response: “They will improve it – don’t worry!”. What this response does, it just puts you off looking for actual solutions to the problem by pretending that a poor solution will magically turn into a good solution against all odds and limits of physics and society.

      In society, whenever you have a problem to solve, there are some good solutions, and then there are those solutions that cause you to drag your feet endlessly because these wonder solutions act as a distraction and draw resources away from the rest. Everybody has some snake-oil to sell.

      1. This competition isn’t the real world, but it has lead to cunning innovations in how you extract energy from the panel and use it efficiently. That without it it may never have be done – if there is no way to showcase and demonstrate ideas then the innovations are lost unless they meet an obvious and easily profitable need.

        Competitions like this one, the human powered aircraft contests etc all put people of technical backgrounds together comparing the methods of the other teams. With better ideas getting recycled and polished into something functional.

        Would steam locomotives have gotten anywhere without the competition that made The Rocket a blueprint for future locomotives and proved it actually could be done? Perhaps, but equally we could all have been stuck with cable pulled railways by static engines or horse power alone until some other tech demonstrates its worth the investment to develop and deploy. Heck Steam power itself had be known for centuries before it got any use at all, and if nobody demonstrates and uses such things it may have stayed the genteel scientist’s curiosity not a useful tool.

        1. > but it has lead to cunning innovations in how you extract energy from the panel and use it efficiently

          I see it rather the other way around, since these are mainly student teams. They apply techniques like MPPT, which were developed elsewhere. This is a showcase for existing technology, sure, but not the only one and not a necessary one in that role.

          If you want to justify the race, do it by the challenge of it – don’t try to excuse it by greenwashing.

          1. There is a massive difference between some lab or even purely theoretical “hmm MPPT might work idea” to actually using it. So even if the initial kernel of the idea didn’t come about specifically for the competition the engineering and invocations required to use it…

            And many of these ideas do come from the competitions – it provides the motivation to take what you know and do new things with it. Find elegant ways to use existing tools, or new variant, and combinations. With each team studying the competition and spotting the cleaver new twists being applied that they didn’t think of.

        2. As for the Stephenson’s Rocket steam locomotive, it wasn’t actually the first steam locomotive. It was a /better/ steam locomotive. At the same time, it represented the culmination of increasing engineering knowledge and better practices, which means that a similar thing was coming along anyways – if not by Stephenson then by anyone else.

          For the latter point, it was already known that such things were possible, which is why the rules of the competition set particular limits on the weights and sizes of the locomotive to just beyond what was thought to be too easy. It was actually the rules that made Stephenson win, because they favored a smaller, lighter, less powerful locomotive. It was a combination of all the best technologies at the time, but more than that it was an exercise in /optimization/ for the constraints of the competition.

          When the competition was over, the Rocket served as a sort of blueprint for its class, but the actual development diverged rapidly because it wasn’t suitable for rail transport as it was.

          >Such are the changes in the engine from 1829 that The Engineer magazine, circa 1884, concluded that “it seems to us indisputable that the Rocket of 1829 and 1830 were totally different engines”.

          1. The locomotives that entered the trails are the only ones worthy of the name up to that date. Yes the basic concept of self moving steam power existed, but nobody had done it at all effectively.

            The competition created a reason to try, and more than one very effective (by the existing standards) locomotive, which proves the effectiveness and practicality of the concept. Adding in new innovations in their constructions. Which means its suddenly getting attention and development – you wouldn’t get a new steam locomotive design in a year if there wasn’t suddenly profit to be made.

            To say such a thing would come about quickly without it is rather preposterous – if nobody wants, is willing to pay for, or use a new idea nothing changes. And in almost every case of technology moving on its because the idea has proven itself, usually via competition. If something like it was just going to turn up than the ancient Greeks would have had massive stationary steam engines at the minimum, they already had all the core elements and understanding to do so. Bloody hell water and wind power for anything but milling of grains doesn’t even happen for ages after the tech is proven! With the only relatively early example of using such power for anything else I’m aware of being a blacksmiths ‘power hammer’ – something that no matter how primitive immediately shows its use and will turn a profit…

          2. >The competition created a reason to try

            One would think the need to transport goods and people created a reason to try – not the competition. Why do you think the competition was made in the first place?

            The competition created a particular set of constraints that resulted in a particular type of locomotive to win the race – collecting all the best science of the day into a single showpiece unit – yet this locomotive was not useful as-is and was quickly re-modeled to fit the actual purpose.

          3. In fact the ancient Greeks did have versions of massive steam engines and they did use them for some niche applications like opening and closing certain temple doors, but since they were pretty much reduced to fueling them with huge quantities of wood carried around by people, it was simply too expensive to run them for any purpose.

          4. Dude before the railways all the money was in canals and water transport – the needs to get goods around provides some motivation, but if there is no funding or excessive demand (which creates funding) it doesn’t happen. The trails came about because a very small number of wealthy folk thought they stood to gain, but it was far from a given they were not wasting their time. If the competition had not be run, with the state of locomotives generally at the time, and the lack of development and cross pollination of ideas if created would have held back practical locomotives for a long time – possibly forever. There would have been lots of money to be made in building new canals, and huge vested interest by the current canal owners in keeping their monopoly with nobody willing to bankrupt themselves pushing a ‘fantasy’ of unproven tech – it takes some bold backers and such a competition (which pushes most of the finacial risk onto the shed dwelling engineers building something at the cutting edge) or huge unmeetable with current tools demand (which creates such obvious sure profits to those in the situation to take it will, even more so if it breaks a rivals monopoly on similar tools) to create a situation in which new technologies are developed and deployed…

            Yes without coal or oil early steam engines would be harder to fuel, but the power and efficiency of a beam engine (to stick well within the feasible for what we know they knew) would have been gamechanging – if they had the will to develop it – but an empire largely powered by serfs and slaves has no need of mechanisation – so it doesn’t happen as those in power like the way things are, and were the only folks who mattered. They would only do so if they suddenly felt the need – perhaps to pump drinking ground water knowing some rival empire is looking likely to invade and current demand inside the cities is far to high to be met while under siege or to load and perhaps power larger catapults etc…

            There is a reason technology has moved on hugely and faster in recent years – largely because sharing ideas has become trivially easy, so the good idea, elegant, novel or cunning solutions are picked up globally in pretty short order – which exposes more minds, who add their own improvments – which is what these competitions are good for. In the days before easy global travel or communications such things almost never happened – you want to invent anything you have to invent every element yourself in a vacuum, and when your design some decades later happens across another maker with the right background they might figure out how to replicate then improve it with the materials they have. Where now something anybody documents gets feedback that might be useful in hours and provides a base for others to build their own interpretation from – and it doesn’t matter if there’s not a source x to mine/harvest etc for thousands of miles it costs nothing (comparatively at least) to bring something round the entire globe…

  6. I just know that seeing a highlights reel of this competition was very entertaining and thought it was a great project for college kids to do. That was many years past. Would like to see the latest competition to see what has improved. The drivers were very hot and horizontal back then.

    1. I’m with you!

      The point is that making a solar car (go faster) is a crazy, bonzo feat of engineering. Of course you have to sacrifice creature comforts.

      I think it’s amazing that there is a “cruiser class” at all. Going from an aluminum-frame recumbant bike with a solar panel to something that could possibly carry you and groceries _at all_ is a testament to how far electronic motors, transmissions, aerodynamics, batteries, and yes, solar cells, have come in the last 30 years.

      Not practical or pedestrian or utilitarian. Challenge.

  7. Only humans suffering from CAPITALISM would put solar panels on the car and not make the road covered….only humans be so blind! Refusing to do the right thing equal never get it right…stop the nonsense and get the power from other than the cars or plain just stop insulting the planet with the lack of effort.

  8. Funny, I was reading an article on Yahoo yesterday that said they had gotten a solar
    cell up to just below 30% efficiency. I showed the article to a friend and his first
    comment was “and that will price solar cells out of the reach of the average consumer.
    What I’d like to know is, why do solar panels stop working after a time?
    I remember reading that somewhere, but for the life of me, can’r remember where.

    I’ll just leave this here…

    1. 30% is indeed nice, but only gamechanger for size contrained application.
      For everyday use (ie roof mounted array) the issue is mainly bureaucraty making it difficult and more expensive that it need.

    2. Why they stop working?

      Probably first in line is the physical damage to the cells: de-lamination of the panel, slow diffusion of water into the cells causing corrosion, yellowing of the anti-reflective coatings, scratches and dings, hail, snow loading, wind picking up the panel and yanking it off the roof… etc. or just the old fashioned Dennis the Menace happening: baseball through panel. There’s also solar panel theft.

      Then there’s heat damage, causing electromigration and diffusion across the P-N junction which degrades the cells. Shading on a part of a panel causes the rest of the panel to dump power onto that cell, which creates a hot spot that causes accelerated fading in the cell and in extreme cases can crack the glass. Insulation and sealing fails after a while, wires corrode, etc.

  9. “For 2021, regulations will again change to focus on driver comfort, dynamic stability of competition vehicles, and include new safety features like daytime running lamps. ”

    In those few words, a great example on our relationship to efficiency.
    Also known as Jevons paradox.

    1. The “efficiency” of the solar vehicles are gained through a total compromise of practicality. None of the solar challenge cars are truly road legal in the first place, so instead we’re talking about finally meeting the minimum requirements for ANY real “consumption” to take place.

  10. “..what used to be impossible is in fact achieved by multiple teams in under one tenth of the original time.”
    What does that even mean? What was impossible that is now achieved? If it was impossible, then what was the original time?
    Are you saying that before solar panels were invented people couldn’t power cars with sunlight, so it was impossible?
    Are you saying that now people are powering car-shaped bicycles and build them faster than they built them 30 years ago?

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