Published on June 6th, 2017 | by James Ayre1
Solar Cars 101 — Guide To The Basics Of Solar Powered Vehicles
Are solar powered cars viable in any real way? Is there a way to create vehicles that are powered by nothing but solar photovoltaic panels and that are useful in the real world? Is it possible to create solar cars that are competitive commercially? What kind of vehicle performance can be achieved when the added weight of solar panels or cells and battery packs are taken into account? What sort of max range could a solar-powered car cover in a day’s time?
All interesting questions … and ones that are hard to get a clear answer to — partly owing to the fact that the technology is a relatively new one and partly owing to the reality that the internet is largely an echo chamber of people who don’t bother to know what they are talking about (and who often have no real-world experience).
With that in mind, what this article proposes to do is to provide a basic overview of the current state of solar car technology and also of the possibilities. We’ll start this off with a discussion of solar-powered cars that have been designed and created by researchers.
The Basics Of Solar-Powered Cars
So, what exactly is a solar car? A solar-powered car is a car that utilizes integrated solar photovoltaic (PV) cells that convert sunlight into electricity to drive electric motors, which then move the vehicle in question.
Generally speaking, solar-powered cars are built from ultralight materials in order to make up somewhat for the energy constraints inherent in the tech, but there is otherwise quite a bit of variance as regards body design — though, drag coefficients are often quite low to increase driving efficiency.
In addition to solar PV cells and basic equipment, solar-powered cars often also feature battery packs to store generated electricity, and thereby allow travel even when the sun isn’t out (or the sunlight isn’t very strong).
Solar-Powered Cars Made By Researchers
The first thing that we’ll discuss here are the “solar cars” made for the Tour de Sol race in Switzerland back in 1985. I put that in quotes because the “cars” were essentially just trikes (most of them anyways), most with solar cells attached to them one way or another.
Recent solar cars that seem worth mentioning here include the Stella Lux — which was created by students in the Netherlands as the “first solar family car.” In other words: it can seat a family, has a range of 550 per charge; and can essentially (somewhat) function as a normal car. That said, it weights just 850 pounds, would probably get utterly destroyed in a collision with a typical internal combustion engine (ICE) vehicle, and looks somewhat normal. The Stella Lux, notably, has an essentially infinite range when traveling at 45 miles per hour in good sunlight.
Solar Car Races & Competitions
Most solar cars that have been created over the last few decades have been as a result of the many solar car races that are no put on regularly. Typically these solar races see vehicles created by teams at various large universities and businesses around the world pit their creations against one another along long, arduous (but sunny) routes in the US, Australia, and Europe.
The World Solar Challenge, which you may have heard of, has been a regular event for the last few decades now in Australia, and sees competitors attempt to traverse the whole continent in a solar powered car. Notably, in recent years, event organizers have introduced a “Cruiser Class” competition — which sees “practical” solar car creations compete against one another, rather than the highly specialized solar car creations that one typically sees.
The American Solar Challenge racing events, by contrast, were based out of the US, and saw mostly university teams competing against one another in a very different sort of setting.
Other major solar car racing events include: the Dell-Winston School Solar Car Challenge (high-school teams); South Africa’s Sasol Solar Challenge; Formula-G; World Green Challenge; and the World Solar Rally (in Taiwan).
Limitations Of Solar-Powered Cars
There are some limitations inherent in the design of solar-powered cars, as alluded to already, such as space limitations on the surface and roof of a vehicle for solar cells (and thus energy limitations, and range limitations); and also limited capacity to carry heavy batteries (thus energy storage limitations as well, and range limitations). The weight of solar PV cells is another limiting factor.
While these limitations may be lessened to some degree or other over the coming years as a result of falling battery and solar cell costs, they will likely always remain as important factors to consider when determining the practicality of a solar-powered car. As a result, in most circumstances, an electric car paired with a ground- or roof-mounted solar PV array is likely to be far more practical and economical.
A further limitation that’s perhaps less obvious is that of solar PV cell lifespan and durability. In order to sustain function in the relatively harsh working environment of a vehicle, the solar cells used on solar powered vehicles no doubt have to be made with durability in mind — extreme vibration, possible collisions, etc. While most solar PV cells in common use today can likely outlast the ~11 to ~12 year lifespan of the average car, it’s something that definitely stands as a potential limitation and should be taken into account.
Solar Car Use In Remote Areas Without Charging Facilities Or A Grid
Could solar-powered cars be of use in remote regions without easy access to grid electricity?
How does the idea of a solar car compare to the idea of lugging around a solar PV array and batteries that are deployed when not traveling? Not very well for the car carrying a separate solar energy system — as not only would such a solar + batteries system take up precious storage space that a system integrated into the roof would not, but it also wouldn’t function while traveling, while an integrated system could function to some degree or other while driving.
The environment that I’m thinking of when discussing this is one where sunlight and space are in abundance, and shade and charging facilities are rare — so perhaps parts of Australia, western North America, southwestern South America, parts of Africa, Asia, etc. After all, there are quite a number of places where it would be handy to have vehicles that can make it out of desert regions even if fuel/batteries run out.
While such a use would be niche enough that major auto manufacturers would probably never bother to release anything relevant, the niche could possibly attract the attention of various fleet conversion firms. Or not. In which case those interested would have to pay someone to do a conversion for them, or do one themselves.
Commercialization Of Solar Cars?
So are solar powered cars ever likely to be commercialized? It seems unlikely to occur except possibly in various niches where such vehicles could prove worth the extra costs, and limitations, associated with them.
Is there any middle ground, though, where solar PV cells could be integrated into the bodies and roofs of electric vehicles and prove useful? That brings us to our next section.
Current Commercial Car Models With Solar Roofs (Both Standard & As An Option)
What options are out there now for those looking for an electric car with solar PV cells integrated into the roofs? Not many. The main options being the Fisker Karma, the Karma Revero (the new rebranded and updated Fisker Karma), and the Japanese version of the Toyota Prius Prime.
It should be noted, though, that Tesla CEO Elon Musk has stated that there will eventually be a solar roof option for the Tesla Model 3 — which will presumably utilize the company’s solar glass technology. Presumably, all of Tesla’s vehicles will eventually offer a solar roof option, that being the case.
With regard to the two primary options now available — the Fisker Karma (& the rebranding, the Karma Revero) and the Toyota Prius Prime (Japanese version) — while they are no doubt not useless, they aren’t substantial enough to do anything other than offer a backup means of (slowly) refueling if one was to run out of gas and be somewhere sunny. The Karma Revero roof, for instance, can only provide a couple of miles or so of range per day left out in the sun. While you could consider such an ability to be a cost saver, the increased wear to the car caused by leaving a car out in the sun all the time rather than in a garage needs to be factored in as well.
I guess that it should also be mentioned here that the Chevy Volt, the 2010 Toyota Prius, the Audi A8, the Nissan LEAF, and the Mazda 929 have all be available with solar options in the roofs as well, but these systems were much more limited in scope and primarily provided auxiliary functions outside of regular use — in particular, as a means of powering ventilation systems when parked in the sun.