Solar cars are technically electric cars. What makes them unique from today’s mass-produced electric cars is the fact that they power their batteries from electricity produced by the rays of the sun. That means no fuel requirements, no emissions, and absolutely no carbon footprint.
For electric cars to satisfy the transportation requirements of drivers and families, they must be able to satisfy basic needs for comfort, performance, and reliability:
- Stable and comfortable seating for the driver and passengers
- Capability of transporting essential items such as groceries or luggage when traveling
- Provide a respectable mileage range without recharging
- Generate performance for both city driving and highway travel
There are electric cars that meet all these requirements – and more – but they are battery-powered or hybrid vehicles that utilize both electric motors and gasoline engines.
Most true solar cars built today are either prototypes created with experimental technology for future development, or project cars designed for racing and other competition.
So How Do Solar Cars Work? – the Solar Car Explained
Where the Power Comes From
Solar cars get their power from electric motors, but rather than using strictly battery power for their energy source, they derive their electric power from solar panel arrays built into the vehicle’s surface.
Solar panels utilize photovoltaic cells (PV cells) to transform sunlight directly into electricity by generating electron flow. Although silicon has been the primary semiconductor material utilized in PV cells in the past, and is most commonly found in solar panels, other materials have also been explored, such as gallium arrays. In fact, the University of Michigan Solar Car Team adopted gallium arrays in their most recent solar power project car named Novum.
Gallium arrays offer the advantage of generating electricity more efficiently, and they can be applied in less space than silicon-based panels.
Solar arrays are generally affixed directly to the vehicle’s surface, utilizing the most aerodynamic installation possible. While there are thin, flexible arrays currently under development that will offer more efficient mounting of panels, most solar cars install PV panels directly to the vehicle on multiple surfaces to generate as much electricity as possible.
Electric motors in solar vehicles produce only 2-3 horsepower, yet with the aerodynamic properties and light weight of solar cars, they can operate at speeds up to 100 mph.
Sunlight Is Not Always Present
Obviously, the sun is not always available to generate the power needed for solar car operation. Electricity generated by the panels is also stored in batteries for non-daylight operation.
Batteries in typical solar cars store enough power to operate the car for 250 miles without the benefit of sunlight, with a speed of up to 60 mph.
Materials are critical to efficient operation of solar cars. Frames, brake materials, and suspension construction all contribute to providing high strength but light weight that places less demand on the electrical system. Frames are often constructed of composite or other light yet strong materials. Lightweight wheels and tires also make the vehicle more efficient and capable of traveling longer distances at higher speeds.
Body Styling and Materials
To get the highest efficiency and best mileage from solar cars, when building a solar car designers must take many physical attributes into consideration including:
- Wind drag – aerodynamics play an important part in gaining the best mileage and distance from solar cars built for racing, and the same will be true of vehicles built for sale to the public.
- Body panels – both weight and strength must be considered for utilization in solar car bodies. Multiple materials have been utilized, including aluminum alloys, fiberglass, carbon fiber, and Kevlar panels.
While light weight is important to maximize mileage and reduce power requirements, building a solar car that is overly light can result in handling problems, especially in windy conditions.
Mileage is a Significant Factor
Solar car mileage is today a major consideration in the design and building of production models.
Chinese manufacturer Hanergy is working on solar car prototypes that will include lithium-ion batteries for non-sunlight operation. They estimate that with 5-6 hours of sunlight per day, the vehicle could travel approximately 50 miles strictly on solar power. Maximum range for the vehicle is currently estimated at 217 miles.
This is a considerable variation from existing all-electric cars that are capable of traveling up to 335 on a full charge, according to EPA ratings for the Tesla Model S 100D. You must also take into account the cost of charging an electric vehicle, to get a full comparison of the cost of operating an electric car vs. a true solar vehicle.
Solar Car Markets in the Future
Manufacturers and engineers agree that a total solar car is not practical with today’s technology, and certainly is not seen as being available in the consumer market in the near future.
Even so, solar-powered vehicles are certainly a long-term objective for providing drivers with economical transportation that generates zero emissions while providing a respectable mileage range.