For years, the idea of a car powered by the sun, the most abundant yet underutilized energy source in the solar system, was a pipe dream. A car that doesn’t need gas or even to charge from a grid that may be using nonrenewable energy sources?
It sounds too good to be true, and for a while it was. But the end of fossil fuels is now in sight, and the makers of the future’s technology have focused their efforts on making solar cars a reality. Against all the odds, there have been major developments in solar panel and design technology that has made commercially viable solar and solar assisted cars possible in our lifetimes.
How It Works
Solar vehicles use solar panels to harvest electricity from sunlight. They implement photovoltaic cells on the non-window surfaces of the vehicle to achieve this. Photovoltaic cells become excited when exposed to sunlight, and the photons create a flow of electrons, thereby creating an electric current.
Currently, most photovoltaic cells use silicon in their construction which is about 15 to 20 percent energy efficient. This means that it is only able to convert a small portion of the energy it is exposed to into an electric current. Compared to other sources of energy, such as combustion of gasoline, a photovoltaic cell provides a mere trickle of energy.
However, solar power relies on quantity over quality to pull its weight. Solar cells are always working, converting sunbeam that touches it into electricity. It needs no refueling, is nonflammable and produces zero emissions. After the cell is purchased, it is virtually free to operate.
A photovoltaic cell’s power source is the sun which is, at least relative to us, an infinite power source. Enough sunlight hits the Earth every hour to supply all of humanity with its energy needs for one year. A car that could take advantage of this would have a virtually unlimited and utterly free power source for its entire existence.
The Current State of Solar
Until recently, solar-powered vehicles were thought of as fantasy, and for a good reason. They have had and still have some serious drawbacks when it comes to powering something as large as a car.
Solar cells are promising for supplying electricity to homes and power grids with clean and renewable energy. In static systems, many massive cells can be used to accrue charge throughout the day. They can also store this charge in batteries to be used when the sun is not out. But things get much more difficult when you apply the technology to something that has to move.
Where Solar Falls Short for Vehicles
A solar-powered car has many more design hurdles than a building. Here are some areas where solar cells can’t quite get the job done.
- Surface Area: A solar cell needs exposure to sunlight, and to achieve this it must have a wide surface area to catch some rays. This causes problems for aerodynamics and handling when making a highway-ready car.
- Weight: Since the energy provided by a solar-powered vehicle is so small in amount, the car must be very light to reduce its energy requirement. Too heavy, and the panels don’t produce enough charge to move the car effectively. A battery to store charge for later use significantly increases weight as well.
- Driving Range: Since batteries must be smaller, the distance that a solar car can travel is also hamstrung. Even plug-in electric vehicles outperform solar here.
- Weather: Of course, the most pressing concern is the availability of solar power. Sure the sun is unlimited, but what about cloudy days? Our solar cells simply are not efficient enough to generate the needed charge without direct sunlight.
All of this may seem like a condemnation of solar vehicles, but researchers are actively addressing each of these problems, and they make improvements every year. Overcoming these barriers now seems realistic.
To address the surface area and weight problems, thinner and more efficient solar panels have been developed. These reduce the total weight of the vehicle and cut down on drag, which then reduces the energy requirement of the car.
Battery technology has also improved exponentially as electric cars break into the mainstream. Lighter, more energy dense batteries allow for longer driving ranges. These technological leaps particularly benefit plug-in solar assisted vehicles. More on those later.
Current Applications of Solar Power for Vehicles
Despite fully solar cars dominating the roads being decades away, there are already technologies and systems available that help transport people where they need to go. These range from small accessories to full solar conversions.
1. Solar Charger for Car Batteries
One of the most innocuous ways solar panels are aiding transportation is the solar battery charger. These have found use charging power banks, phones and other portable gadgets, chargers have also been designed for car batteries. They consist of a small solar panel about the size of a lunch tray that hooks up to your car battery.
This panel recharges your car battery, or rather, keeps it charged. It is theoretically possible to charge a dead car battery with it, but it will take awhile. It works much better at keeping the battery charged, so it doesn’t die in the first place.
2. Solar Assisted Electric Vehicles
At our current state of technology, solar is more viable in hybrid form. Just as gas-powered cars benefit from combining with plug-in technology, so too does solar technology. By adding solar panels to a plug-in electric vehicle, the driving range is greatly increased.
As the car is driving, it slowly recharges its battery with top-mounted solar panels adding much need miles to its maximum distance. This development is critical, as driving range is one of the major barriers to widespread adoption of electric cars by average consumers.
Of course, this is reliant on weather, and its possible that the solar panels very little on a cloudy day. However, the weight of the car is not significantly affected by the panels as they are so light and costs fall every day. Additionally, some designs for solar and solar assisted cars allow the vehicle to feed electricity into the grid while it is parked and plugged in. These solar assisted cars are finally becoming commercially viable.
3. Fully Solar Cars
While not yet available for average consumers, entirely solar cars are well on their way to commercial viability. They still suffer from design barriers, but solar panel cars are slowly becoming more like options rather than oddities. Their intermittency and low performance are the focus of solar-powered car companies’ troubleshooters
These fully solar powered cars differ from solar-assisted electric vehicles in that they do not have a plug-in feature. This greatly reduces their capabilities but also reduces the weight and complexity of the car. The batteries used in fully solar cars aren’t nearly as substantial as the massive, heavy battery packs of current electric vehicles
One could be forgiven for not wanting to drive a fully solar car, imagining it might look like a table with solar panels and wheels. However, solar car companies are thinking bigger and have manufactured fully solar prototypes that carry up to five people.
The Solar Car Challenge
One of best places to witness developments in solar car technology is the World Solar Challenge. This competition brings in solar car teams from around the world who have built their own vehicles. These teams, either from companies or universities, race their custom built solar cars to demonstrate their design and technology achievements.
The competition takes place in Australia where sun availability is not usually a problem. Competitors race across the outback over several days to test their solar car’s speed and endurance. These cars are all fully solar; no plugins are allowed. However, some batteries are allowed to power subsystems.
The main competition is based on speed, referred to as the Challenger Class. The first car across the finish line wins. The Cruiser Class, on the other hand, measures drivability and commercial viability.
They award cars that best approach the demand of the market, thereby promoting the idea of widespread adoption of fully solar-powered cars. Every two years, the World Solar Challenge showcases the best, and brightest solar has to offer and gives a glimpse of the future.
Keeping the Dream Alive
Even the staunchest of solar vehicle supporters will admit that several significant stumbling blocks are preventing widespread adoption of solar-powered cars. At the same time, however, even the skeptic must see that recent advances in solar technology have made fully solar-powered vehicles or at least solar assisted vehicles a viable choice for the future on energy independence.
The prospect of free and limitless energy for transportation is too good to ignore and is worth the effort and wait.