Solar cars in the UK

Here is a list of 4 active UK solar car teams. On 26th September, Durham has invited all the UK teams to a friendly track race at Dunsfold Aerodrome, site for the BBC television series Top Gear. A sort of “Top Solar Gear,” I guess.

A retired 747-200, registration G-BDXJ, parked at Dunsfold Aerodrome – so it will be true to say that the solar cars will be faster than the 747.

20  GB  Durham University Electric Motorsport 

Asymmetric challenger (Ortus) – Durham are the UK’s premier team. They have been upgrading their car after racing in Australia in 2019. They are one of the few teams to report a CdA value (0.107 for Ortus). They displayed great initiative by running their own Ouston Solar Challenge when Covid-19 prevented their travel to iESC 2020. They are currently engaged in a Solar Tour of the UK as an outreach activity, concluding with the Dunsfold event.

Previously, Durham came 27th at WSC 15; participated at WSC 17; and came 14th at WSC 19.

Left: Anthony Dekker / Right: credit (click images to zoom)

12  GB  Cambridge University Eco Racing 

Four-seat cruiser (Helia) – they will be staying in the UK this year, and attending the British Motor Show.

Previously, Cambridge came 22nd at WSC 15; participated in the WSC 19 Cruiser class; and came 10th at iESC 16.

Left: Nigel / Right: credit (click images to zoom)

23  GB  University of Nottingham Solar Racing Team 

Cruiser (new team) – their rather radical approach is to modify a Renault Twizy to have solar panels, improved electrics, and second life Nissan Leaf batteries. They aim to participate at iESC 2022 with their first car.

photo: UoN team (click image to zoom)

43  GB  Ardingly Ifield Solar 

Two-seat cruiser (Ardingly Solar Car) – this high-school team came 6th in the 2018 iESC Cruiser class, and have upgraded the car since then. They also did a UK solar tour, and also attended the British Motor Show.

Previously, Ardingly participated in the WSC 15 Cruiser class; participated in the WSC 19 Adventure class; came 6th in the iESC 18 Cruiser class; and participated at Albi Eco 19.

Left: Anthony Dekker / Right: credit (click images to zoom)

Solar cars: Belgium and Morocco

Here is a list of 17 European teams from 11 countries (including Turkey and Morocco) – 11 Challengers and 6 Cruisers – intending to race in two major upcoming solar car events in the region this year. These events are:

  • iESC  iLumen European Solar Challenge        (16–19 September): Aachen, Agoria, Onda, Bochum, Twente, SER, ITU, Eindhoven, Lodz, Chalmers, PUT, Solaris, and Cluj
  • SCM  Solar Challenge Morocco (23–29 October): Solaride, Delft, Top Dutch, Aachen, Agoria, Twente, and Chalmers

In other recent news, several new cars have been revealed, and there was a small solar car event in Sweden.

SCM  EE  Solaride  

Two-seat cruiser (new team) – this new team from Estonia has built a good-looking Cruiser. They are based in the city of Tartu.

picture credit (click image to zoom)

SCM  NL  Vattenfall Solar Team (Delft) 

Three-wheel (outrigger) challenger (new car: Nuna11) – this year will be the last year that Delft partners with Vattenfall. Starting in 2022, Brunel will be their main sponsor. They have been recruiting for the 2022 Sasol Solar Challenge, and will also race in Morocco. Their new car features an asymmetrical top surface (to create more downforce on the left wheel), a new motor controller (suitable for hills), and a LiFePO4 battery.

Previously, Delft won WSC 13; won WSC 15; won WSC 17; came 12th at WSC 19; won SASOL 14; won SASOL 16; and won SASOL 18. Their team number (3) is a long-standing tradition.

Left: credit / Right: credit (click images to zoom)

SCM  NL  Top Dutch Solar Racing 

Challenger (new car: Green Spirit) – they are hoping to race their new car in Morocco.

Previously, Top Dutch came 4th at WSC 19 and came 3rd at iESC 20.

Left: Anthony Dekker / Right: credit (click images to zoom)

SCM  DE  Sonnenwagen Aachen 

Three-wheel (outrigger) challenger (new car: Covestro Photon) – this team did very well in 2019, in spite of being blown off the road. They are excited about racing at Zolder again. They will race 2 cars at Zolder: the new car (7) and the previous car (70). In Morocco they will race as number 7.

Previously, Aachen participated at WSC 17; came 6th at WSC 19; came 3rd at iESC 18; came 5th and 8th at iESC 20; and came 2nd and 6th at iESC 21. Their usual team number (70) is the number they raced with in 2017.

Left: Anthony Dekker / Right: credit (click images to zoom)

SCM  BE  Agoria Solar Team / KU Leuven 

Three-wheel (tadpole) challenger (new car: BluePoint Atlas) – they have built a new car to defend their title. It is named after the Atlas Mountains. They are racing their previous car (BluePoint) at Zolder.

Previously, Agoria came 6th at WSC 13; came 5th at WSC 15; came 3rd at WSC 17; won WSC 19; came 3rd at Abu Dhabi 15; came 2nd at iESC 16; came 6th at iESC 18; came 1st and 6th at iESC 20; won iESC 21; and won Carrera Solar Atacama 18. Their team number (8) is a long-standing tradition.

Left: Anthony Dekker / Right: credit (click images to zoom)

IT  Onda Solare 

Four-seat cruiser (Emilia 4 LT) – they won the American Solar Challenge (Cruiser class) in 2018, and they have written up their design process here, but they have since made substantial improvements to the vehicle, including to the aerodynamics, suspension, battery, and solar panels. There is also an unusual open tail.

Previously, Onda came 10th at WSC 13; participated in the WSC 19 Cruiser class; won the ASC 18 Cruiser class; came 10th at Abu Dhabi 15; came 6th at iESC 16; and won the iESC 21 Cruiser class. Their team number (9) is taken from the SS 9, the highway through Bologna, which was once the Roman Via Aemilia (hence also the name of their vehicle).

Left: credit / Right: credit (click images to zoom)

11  DE  Hochschule Bochum Solar Car Team 

Two-seat cruiser (thyssenkrupp SunRiser) – for the 2019 World Solar Challenge, Bochum improved their sexy 2-seater SunRiser, which came 3rd in 2015. They also have a solar buggy team. Their current plans involve a hybrid solar-hydrogen vehicle, called SolaH2, based on a 2003 vintage Land Rover Defender 110. They will race two cars at Zolder (the SunRiser and the older SolarWorld GT as 11 and 42 respectively).

Previously, Bochum came 2nd in the WSC 13 Cruiser class; came 3rd in the WSC 15 Cruiser class; came 2nd in the WSC 17 Cruiser class; came 4th in the WSC 19 Cruiser class; came 3rd, 4th, and 5th at iESC 16; came 2nd, 3rd, and 5th in the iESC 18 Cruiser class; came 3rd and 4th in the iESC 21 Cruiser class; came 1st and 7th at Albi Eco 18; and came 1st and 2nd at Albi Eco 19.

Left: Anthony Dekker / Right: credit (click images to zoom)

21  SCM  NL  Solar Team Twente 

Three-wheel (tadpole) challenger (new car: Red Horizon) – they have built a three-wheeler this year, and will race both at Zolder and in Morocco. Their Zolder car will be their 2019 RED E.

Previously, Twente came 3rd at WSC 13; came 2nd at WSC 15; came 5th at WSC 17; came 17th at WSC 19; won iESC 16; came 1st and 2nd at iESC 18; came 2nd and 4th at iESC 20; and came 3rd at iESC 21. Their team number (21) is a pun and a wish for success in the race (“Twente-One”).

Left: Anthony Dekker / Right: credit (click images to zoom)

31  CH  Solar Energy Racers 

Challenger (new car: SER-4) – they raced their SER-3 in South Africa and Australia. However, they still have their SER-2, and will race that at Zolder again. They are also building a new SER-4.

Previously, SER came 5th at WSC 13; came 15th at WSC 19; came 2nd at ASC 16; came 11th at Abu Dhabi 15; came 3rd at SASOL 18; came 8th at iESC 16; and came 4th at iESC 21.

Left: credit / Right: Anthony Dekker (click images to zoom)

34  TR  Istanbul Technical University (ITU) 

Challenger (new car: Ariba X) – they discuss their plans here. They have built a new car to replace their older B.O.W.

Previously, ITU came 17th at WSC 13; participated at WSC 17; came 7th at iESC 16; came 7th at iESC 20; and came 8th at iESC 21. Their team number (34) is the vehicle license plate prefix for Istanbul.

Left: Anthony Dekker / Right: credit (click images to zoom)

40  NL  Solar Team Eindhoven 

Cruiser (new car: Stella Vita) – after building four “solar family cars,” their focus for 2021 is a Self-sustaining House On Wheels. They also took their Stella Era to Zolder, although they were prevented from racing.

Previously, Eindhoven won the WSC 13 Cruiser class; won the WSC 15 Cruiser class; won the WSC 17 Cruiser class; won the WSC 19 Cruiser class; came 7th in the iESC 18 Cruiser class; and came 1st and 2nd in the iESC 20 Cruiser class. Their team number (40) is the Eindhoven telephone area code.

Left: Anthony Dekker / Right: credit (click images to zoom)

45  PL  Lodz Solar Team 

Four-seat cruiser (Eagle Two) – this team has some nice (Polish) news coverage here. They are working on improving their car.

Previously, Lodz participated in the WSC 15 Cruiser class; participated in the WSC 17 Cruiser class; participated in the WSC 19 Cruiser class; came 5th at SASOL 16; won the iESC 18 Cruiser class; and came 2nd in the iESC 21 Cruiser class. Their team number (45) is a tradition since 2015.

Left: Anthony Dekker / Right: credit (click images to zoom)

51  SCM  SE  Chalmers Solar Team 

Three-wheel (tadpole) challenger (new car: Sköll) – they were the first Challenger-class team to reveal a render for their new car.

Previously, Chalmers came 21st at WSC 19; came 5th at iESC 21; and participated at Swedish Solar Race 21.

Left: credit / Right: credit (click images to zoom)

77  PL  PUT Solar Dynamics (Poznań University of Technology) 

Two-seat cruiser (new team with car: Klara) – they have revealed their car, which weighs 750 kg and has an 18.5 kWh battery. This (Polish) video describes their project. Sadly, they had pre-race electrical problems at the Zolder racetrack.

Left: credit / Right: credit (click images to zoom)

77  MA  Mines Rabat Solar Team 

Asymmetric challenger (new car: Eleadora 2) – they have worked hard to complete this car (see this video).

Previously, Mines Rabat participated at MSRC 19.

Left: credit / Right: credit (click images to zoom)

81  TR  Solar Team Solaris (Dokuz Eylül University) 

Challenger (new car: S11) – they missed the last ESC, but are attending in 2021 with their new car.

Previously, Solaris participated in the WSC 13 Adventure class; came 25th at WSC 15; came 18th at WSC 19; came 9th at iESC 16; came 7th at iESC 21; came 2nd at Albi Eco 18; and came 2nd at MSRC 19.

Left: credit / Right: credit (click images to zoom)

99  RO  TU Cluj-Napoca Solar Racing Team

Challenger (new team with car: SolisEV-1) – this is a brand-new team from Cluj-Napoca in Romania. They appear to have no online presence at all (although their institution does have a Formula Student team) but they are present at the track.

Previously, Cluj came 9th at iESC 21.

public domain photo

This page last updated 20:08 on 25 October 2021 AEDT.

Head to head in Sweden

Right now, at Anderstorp Raceway in Sweden, Chalmers Solar Team ( ) and Halmstad University Solar Team ( ) are participating in the two-day Swedish Solar Race and display event (17–18 August). Here are the two cars (Sköll and Heart 4), each with three wheels. Both teams are building on their experience racing in Australia in 2019. I wish I was there!

Left: credit / Right: JU Solar Team (click images to zoom)

Update: Unfortunately, Halmstad University (HUST) had a battery fire. There was therefore no competitive race on the second day, and no live-stream.

Fast Fibonacci numbers

There was some discussion on reddit recently of the Fibonacci numbers (1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1,597, 2,584, 4,181, 6,765, 10,946, 17,711, 28,657, 46,368, 75,025, 121,393, 196,418, 317,811, 514,229, 832,040, …) and efficient ways of calculating them.

One way of doing so is using numbers of the form a + b σ where  σ is the square root of 5. Multiplication of such numbers satisfies:

(a + b σ) × (c + d σ) = ac + 5bd + (ad + bc) σ.

We can define the golden ratio φ = (1 + σ) / 2 and also ψ = 1 − φ = (1 − σ) / 2, in which case the nth Fibonacci number Fn will be exactly (φn − ψn) / σ. This is known as Binet’s formula.

We can use this formula to calculate Fibonacci numbers using only integer arithmetic, without ever evaluating the σ. We will have:

(2 φ)n − (2 ψ)n = (1 + σ)n − (1 − σ)n = 0 + p σ

for some integer p, and division by a power of two will give Fn = p / 2n.

I am using the R language, with the gmp package, which provides support for large integer matrices, and this allows us to use the relationship:

If we call this matrix A and calculate An−1, the first number in the resultant matrix will be the nth Fibonacci number Fn. The following R code calculates F10 = 55 using a combination of multiplication and squaring:

n <- 10

A <- matrix.bigz(c(
	1, 1,
	1, 0), 2)

p <- function(n) {
	if (n == 1) A
	else if (n %% 2 == 1) A %*% p(n-1)
	else {
		b <- p(n/2)
		b %*% b


This same code will calculate, for example:

The time taken to calculate Fn is approximately proportional to n1.156, with the case of n = 1,000,000,000 (giving a number with 208,987,640 digits) taking about a minute.

Rods and cones in the human eye

I already posted these images (click to zoom) on Instagram. They illustrate the sensitivity to colour of the rods (lower right) and the three types of cones in the human eye. Cone sensitivity data is from CVRL.

Notice that red light is pretty much invisible to the rods. This is why red light does not interfere with night vision, and is used in e.g. this aircraft cockpit:

Greenhouse emissions in Australia

I thought I would take the opportunity today to talk about energy production and greenhouse gas emissions in Australia. The chart below shows the populations (blue bars) and population densities of the six Australian states plus the Northern Territory. Note that New South Wales, Victoria, and Queensland have the highest populations (8.2, 6.7, and 5.2 million respectively), while the Northern Territory has the lowest. However, given its smaller area, Victoria has the highest population density (29.4 people per sq km), while Western Australia and the Northern Territory have the lowest population densities (1.1 and 0.2 people per sq km respectively).

The next chart shows the per capita electricity production of the six Australian states and the Northern Territory, by type. These figures are adjusted for net electricity transfer between states. For example, Tasmania imports some mainland coal-fired power.

Notice that the totals are high in the less densely populated regions (Western Australia and the Northern Territory). The total is also high in Tasmania, because of the widespread use of hydro-electrically produced electricity for heating there.

Total per capita electricity production is lowest in Victoria, in part because of the widespread use of natural gas for heating and cooking (total gas use in Australia generally is about 4 times its use in electricity production). Victorian electricity is the dirtiest, however, with heavy use of brown-coal-fired production. Brown coal is by far the dirtiest fuel; it produces about 47% more greenhouse gases per MWh than black coal, and triple the greenhouse gases per MWh of natural gas.

South Australia has achieved 50% renewable energy, but this is not without its problems:

  • Wind and solar power are more expensive, so that South Australians pay about $360 per MWh for their electricity: 44% more than the two large states
  • The sun does not always shine and the wind does not always blow: this means that, in the absence of massive-scale energy storage, South Australia has to “borrow” coal-fired power from the East, although this is eventually repaid with interest
  • Solar and wind power cause substantial grid stability and grid synchronisation issues, which become very apparent at the 50% renewable level – good solutions are needed for this; South Australia currently copes by turning solar power off

To avoid “borrowing” electricity, massive-scale energy storage is required. South Australia would need several days worth of demand, at 40 GWh per day. Their famous Tesla battery has been expanded to a capacity of just 0.2 GWh, which is about a thousandth of what is needed. Batteries appear inadequate for energy storage at the required scale, and hydrogen storage is probably what we want.

Tasmania operates at a 92% renewable electricity level, thanks to multiple hydroelectric dams, which do not suffer from the problems of wind and solar (and availability is only an issue during lengthy droughts). In addition, hydroelectric dams can also provide energy storage for solar and wind power, simply by pumping water uphill. It is unfortunate that environmental groups in Tasmania have campaigned heavily against hydroelectric power.

The last chart shows the per capita CO2-equivalent emissions for state electricity generation, plus other emissions (including agriculture, other energy use, industrial processes, waste, forestry, and land use change). Agricultural emissions are highlighted in green. A note of caution, however: the electricity generation data is for 2019, but the total greenhouse emissions are for 2018 (the latest I could find). These numbers cannot be compared to those of other countries, unless the numbers for other countries are equally recent and also include the full range of emissions, per UNFCCC standards (some comparable national averages are shown on the left).

Note that net greenhouse emissions for Tasmania are negative, largely due to tree-planting. Per capita emissions for the large, less densely populated areas are higher than those for New South Wales and Victoria; in part due to transportation requirements (shifting commuters and freight from road to rail would help here). Agricultural emissions per capita are particularly high in the Northern Territory, because the impact of cattle farming is being divided among a tiny population of just 0.2 million people. The overall Australian average of 21.2 tonnes per capita is quite significantly affected by the inevitably high emissions for the large, less densely populated areas. There is also the question of whether emissions due to mining and agriculture should be attributed to the producing country, or to the country of final consumption.

Economically and geographically, Australia is in many ways more like a Central Asian country than a European one, given its large size and its heavy reliance on mining and agriculture (Australia’s greenhouse emissions are comparable to those of Kazakhstan, which produces 21.7 tonnes per capita). However, progress could be made in Australia with more energy-efficient housing and transportation.

It should also be emphasised that, given its small population, Australia’s greenhouse emissions make a neglible contribution to the global and regional climate. If increasing atmospheric CO2 has an effect in Australia’s region, that is due primarily to emissions by the large countries of the world, particularly China (which produces about a third of the world’s CO2). Australia should, no doubt, reduce its greenhouse emissions, but whether Australia does so or not will make no measurable difference to the global or regional climate.

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: road race, Day 4

Today sees the end of Day 4 and Stage 2 of the American Solar Challenge. Above (click to zoom) are the SOV standings at the end of Day 4, in Colorado flag colours. MIT leads, followed by Principia and Kentucky. Teams in red 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, leaving App State in the lead. There is one short day of racing still to go.

Above (click to zoom) is the Gato del Sol VI of Kentucky visiting Fort Union National Monument. Marion Sloan Russell, who travelled the Santa Fe Trail multiple times, was an “army wife” there for some time. In her memoir, Land of Enchantment, she writes about revisiting the site:

At Fort Union I found crumbling walls and tottering chimneys. Here and there a tottering adobe wall where once a mighty howitzer had stood. Great rooms stood roofless, their whitewashed walls open to the sky. Wild gourd vines grew inside the officers’ quarters. Rabbits scurried before my questing feet. The little guard house alone stood intact, mute witness of the punishment inflicted there. The Stars and Stripes was gone. Among a heap of rubble I found the ruins of the little chapel where I had stood—a demure, little bride in a velvet cape—and heard a preacher say, ‘That which God hath joined together let no man put asunder.’

ASC 2021: road race, Raton Pass

The American Solar Challenge has reached the 7,840 ft (2,390 m) Raton Pass. The updated chart above shows my best estimate of the current state of play in the SOV class. MIT has climbed the pass, as has Principia (and App State in the MOV class).

The Pass is tough, climbing 558 m in 22 km (2.5%), with a maximum grade of 6% on the steepest sections. Marion Sloan Russell, in her memoir Land of Enchantment, writes:

Breaking camp while it was still early, our cavalcade began the steep and tortuous ascent of the Raton Pass. Today we glide easily over hairpin curves that in 1860 meant broken axles and crippled horses. The trail was a faint wheel mark winding in and out over fallen trees and huge boulders.

Principia’s Ra XI climbs the Raton Pass (credit: PrinSolar)

ASC 2021: what about MOV cars?

I have been asked about covering the Cruiser (MOV) cars this year. As the ASC photo above shows, Minnesota was the first team into La Junta (at 18:23:47 MDT). Cruiser (MOV) scoring is complex, but it’s mostly a complicated nonlinear function of speed. External energy usage, number of people in the car, and penalties also have an effect, but they are minor.

The chart below is an attempt to visualise who is ahead (I may not have gotten it quite right). For each team and day, there is a group of 4 bars. Mathematically, multiply the first two bars (distance with and without penalties) and divide by the third bar (the speed derate, which penalises going less than 35 mph) to give the fourth bar. Visually, just add the first two bars and subtract the third. So App State was well ahead on Day 1 (because they averaged 34.1 mph to Minnesota’s 29.6 mph), but Minnesota is well ahead now (averaging 35.6 mph to App State’s 34.3 mph).

To relate these numbers to the official ranks, multiply by the average number of people in the car, and divide by the scaling factor for the day, which is the largest of all the distance bars for that day. For example, for App State on Day 1, 20,548.5 × 2 / 244.1 = 168.36. I emphasise again that the numbers for today are estimates.

For a simpler view, we can just assess the cars based on average speed. The chart below does this, with the dashed red line indicating the target speed: