We are currently traveling over 66,000 miles per hour around a giant nuclear reaction that produces 5x1023 horsepower per second. Let's plug our cars into that.

It's not that simple, but we're working on it. Occam's Razor states that the simplest answer is usually the best one. When did we decide that pumping oil from inside the Earth, refining it into gasoline to run our vehicles with, while releasing poisonous fumes, was the simplest answer?

How Solar Works

The modern photovoltaic cell is built mostly of silicon with some phosphorous and boron. Each silicon atom has fourteen electrons arranged within three shells. The first shell holds two electrons and the second holds eight. Both shells are full. The third holds four but is only half full. The atom wants to fill these holes so it eagerly shares electrons with neighboring atoms.

This is how molecular bonds are formed. Each silicon atom shares an electron with four of its neighbors, forming a solid crystalline structure. This makes pure silicon a poor conductor of electricity because the secured electrons don't want to flow. Impurities are necessary. Phosphorous and boron are added, making up about one out of every million particles.

 polysilicon - building block for many solar cells

Phosphorous has five electrons in its outer shell, so when it bonds to silicon it has one extra. Boron has only three, leaving an extra hole. Silicon laced with phosphorous is negative, or N-type. Silicon with boron is positive, or P-type. When excited by the heat of the sun, electrons move from N-type to P-type, causing an electric charge that can be stored in a battery as Direct Current. An inverter can be used to convert the DC power to Alternating Current.

Silicon is unfortunately very reflective. Protective glass plates further repel sun rays. Even with antireflective coating, solar cells only absorb a fraction of the sun's energy. The most efficient solar cells on the planet, made by Fraunhofer, achieve 44.7% and are too expensive for anyone but NASA. Most home solar panels are under 20% efficient.

A solar car is essentially an electric car that gets its energy from photovoltaic cells. At the heart, there are motors and batteries like any other EV.

The Beginning of Electric Cars

Back to Occam's Razor. Electric cars were the simplest way to get around town at the beginning of the 19th century. Roads connecting cities were poor, so horse or train was the best method for long trips. Gas-powered cars required cranking to start, smelled bad and were noisy. Gasoline was expensive and not widely spread. Steam cars took up to 45 minutes to warm up before driving.

Henry Ford's assembly line mass-production brought down the price of his gas-powered cars. By 1912, an electric car cost double that of a gas one. In the same year, Charles Kittering invented the electric starter. By the 1920s, the road infrastructure had improved and large petroleum reserves had been discovered. Drivers needed gasoline range to get from town to town. The electric car headed into nearly a century in the shadows.

Convenience and economics killed the electric car back then. Environmental stewardship and, once again, economics are bringing it back to life. Pollution and increased fuel prices have made non-gas transportation a good idea. Finally government and big business are pushing for, rather than against, alternative fuel.

The whole time, the sun has been basting the planet in energy. It is time for bright human minds to concentrate on making the most of this power source.

The First Solar Cars

1955 Sunmobile by William Cobb (15 inch model)

At the 1955 General Motors Powerama, engineer William G Cobb introduced the Sunmobile. Using twelve selenium photovoltaic cells, it produced 1.5 volts to turn a motor at 2000 rpm. It spun that power through a pulley with a 3 to 1 gear ratio to rotate the rear axle. It was fifteen inches long.

In 1962, the International Rectifier Company revealed a solar car you could actually sit in. They fitted 10,640 solar cells to the roof of a 1912 Baker electric car. The original Baker had 1 3/4 horsepower and a top speed of 14 mph. The solar panel on top surely did not speed it up.

In the late 1970s, Masaharu Fujita and his Tokyo Denki University research group built a solar bicycle. Then they fixed two bikes together to form a four wheeled car. The result was neither fast nor durable.

1979 Solar Car by Alan Freeman (Registered in 1980)

Englishman Alan Freeman registered his solar car in 1980. The buggy could reach 15 mph and received 140 watts from a roof-mounted solar canopy. It was little more than a pod with a seat and bicycle wheels.

Alabama University professor Ed Passerini exhibited his Bluebird solar car at the 1982 Knoxville, Tennessee, World's Fair. It was lightweight, partly due to lack of batteries, and could only run while the sun was shining.

Also in 1980, Arye Baunstein and the engineering department of Tel Aviv University built a relative solar speedster. Their Citicar created 400 watts from roof and hood mounted cells. It stored the power in eight 6-volt cells. With two passengers, it could reach 40 mph and travel 50 miles.

What Restricts the Solar Car?

Certain physical truths keep solar cars from being what we need them to be. Primarily, solar cells do not draw enough power to carry their own weight. For maximum efficiency, they must face the sun squarely, which is an impossible dream for a vehicle and a star in motion. Earthbound solar panels can be installed where the sun hits most often. They can even move with the sun, but a car is constrained by its shape. Cars are round. Solar panels are flat.

Because of the need to maximize a small amount of energy, solar cars must be light, aerodynamic and as frictionless as possible. A wide solar array tilted toward the sun is like driving a billboard.

Any effective solar car will therefore be lightweight and fragile. Driving it in the real world makes it a butterfly among jumbo jets. No car, no matter how wonderful, ever succeeds if it can't survive a crash. No one will approve it. No one would buy it.

Racing Saves the Day

 the quiet achiever passing through australia in 1982.
 Source - snooksmotorsport.com

In 1982, Hans Tholstrup and Larry Perkins drove the Quiet Achiever 2500 miles from Sydney, Australia, to Perth. That was the birth of the World Solar Challenge.

GM's Sunraycer won the first official race across Australia with an average speed of 42 mph. Corporations and universities joined together with private teams to do things never done before. Competition drives creativity. The level of cooperation between combatants at the WSC is astonishing, with every participant ready to lend a hand or tool to the opposition.

Yet the vehicles designed for the World Solar Challenge and other races are never going to be production cars. They are horizontal solar panels on bicycle wheels with prone drivers in cramped conditions. Every grommet and inch of tape is as light as possible.

In 2013 the Cruiser Class changed things. Race officials created a new division aimed at developing cars with more real world usefulness. Cruiser Class vehicles must carry two people seated upright. The car is judged not only on finish time, but also practicality aspects including comfort, features, cargo space and parallel parking. The 2013 winner seated four and completed the 3000 km trip while only expending 64 kWh. A modern family car would have used 5000 kWh.

Light Years To Go

Ford C-Max Solar Energi (concept)

The quest for a car powered completely by on-board solar is far from completion. Our best efforts have fallen short. The Toyota Prius can cool the car when you're away with solar power. The Ford C-Max Solar Energi can charge by the sun, but only if it's under a magnifying canopy and it takes all day. It has an electric range of 21 miles. Any solar car that is acceptably fast would be crushed like a popcorn box by an ordinary car.

Or Did We Already Invent It?

If the quest is for an electric car that can be powered by the sun, we've already done it. Just forget that the solar panel is not mounted on the car. EVs are rapidly improving in speed range and quality. Charge it with solar-derived electricity and you have a beautifully clean vehicle. A car with a solar panel on it is a turtle, clumsily carrying on its back what it could leave at home.

solar panels catching rays under the sun

The problem, like gasoline at the start of the 19th century, is with the supply infrastructure. Today, with gas stations on every corner, who worries about finding fuel? With a grid-connected solar panel on your house and a charging station in your garage, you'll always have cheap clean fuel.

The next step is supplying sufficient public charging. If public parking lots, malls, businesses and schools added roof-top solar and solar carports, charging can be as easy as filling up.

Should we be worrying about putting solar panels on cars? We should put solar panels on everything else and focus on making the best electric cars possible. When charging stations are plentiful, we'll hardly ever wish for car-mounted solar panels.