Are automobile roofs with solar panels a smart idea?

It’s not exactly a car you can depend on to transport your family to the grocery store and back on a Saturday afternoon, is it? The World Solar Challenge winner in Australia for 2019 is the Agoria Solar Team’s BluePoint solar car, which you can see in the image above.

Only the 2.6 square meters of solar cells buried in the BluePoint’s surface allowed it to traverse 3,019 kilometres (1,876 mi) across the Australian continent. Despite this achievement, the cells’ power definitely couldn’t get you from home to work and back in a single day.

You see, there is no space on the BluePoint for a second passenger or any goods. It can only accommodate one person. In actuality, it is quite little, weighing less than 300 pounds, and having a total volume of roughly 16 cubic feet (not including its lowest half that is cut off). In comparison, the mid-sized SUV that the majority of people in the US drive occupies 36 times as much area and weighs 4,336 pounds.

Why aren’t solar-powered cars practical?

For a normal home to generate the amount of energy its occupants require throughout a year, a solar array the size of 500 square feet is required. The best location for those panels is on a roof that faces south and is tilted at a perfect 30 degrees, give or take a few.

We calculated the number of solar panels required to power an electric vehicle a few years back. We calculated the overall solar panel output for the Nissan Leaf at 50 kilometers per day at 3.44 kilowatts. Under full sun, some of the greatest home solar panels now available produce about 345 watts. If you drive 25 miles each way, you would need 10 of them to generate enough solar energy to power the Nissan Leaf, a small automobile, on its daily commute from work to home.

To generate so much energy, 250 square feet of solar panels are needed on an ideal roof space.

Solar-powered vehicles are therefore impractical. Given that a car’s surfaces are not always aimed in the appropriate directions or are not covered by shade, there is simply not enough surface area on a car for the solar cells to provide enough electricity for the average driver.

But the impracticality isn’t deterring automakers. On their autos, at least a few of them have installed photovoltaic cells behind protective glass. One or more manufacturers also incorporate solar cells into the door and quarter panels, in addition to adding a solar roof or hood.

Here is some additional information on solar car producers:

Car companies that make solar-powered cars

Sono Motors and Lightyear Automotive, two automakers, will soon release electric vehicles with solar-panel roofs that recharge the vehicle’s battery to power the electric motor.

Along with the two businesses mentioned above, Karma, Hyundai, and Toyota also sell hybrid electric cars with embedded solar cells that generate a negligible amount of electricity. Again, we wouldn’t describe these cars as being “solar-powered.” For instance, the 200W of solar cells on the top of the Karma Revero are needed for 105 hours of direct sunlight to fully charge the vehicle’s 21 kWh battery and travel 50 miles.

The average location in the nation receives 5 to 6 hours of full light each day, which translates to the ability to go 2.6 miles per day only on solar power from the Revero’s rooftop solar cells.

Sono Motors

If you reside in Europe, Sono Motors is presently accepting pre-orders for their Sion electric vehicle for 28,500 Euros (about $32,350). Although the business promises that production will start in 2023, it is impossible to predict when it will arrive in America. The vehicle has a 35 kWh battery that can transport people for about 158 miles (255 km) on a single charge.

The Sono Sion features 248 solar cells installed in its roof, hood, trunk, and sides, which is very significant. To put it simply, it has more solar than any other automobile available. Under full sun, it is projected that each solar cell can produce 4.84 watts, and the entire surface of the automobile is capable of producing 1.2 kW.

One issue, though, is that only some of the solar cells will ever receive full sun at any given time having solar cells on the top, hood, trunk, and sides.

Can the Sono Sion charge itself with solar power?

Sono claims that the Sion’s solar-cell-embedded surface may provide “up to 34 kilometers” (21.1 miles) of range per day. Although that sounds like a great deal, is it true?

Sono calculated that the Sion can travel 4.53 miles for each kilowatt-hour of energy that is kept in its battery. We calculated the numbers using the Sion’s body’s location of the cells using NREL’s PVWatts solar estimation tool, and we discovered that (drumroll, please) Sono might be correct.

Sono Sion generation estimate in Santa Fe, New Mexico

Location# of cellsWattage(4.84W/cell)AzimuthTiltGeneration(kWh/year – PVWatts)kWh per day
Driver side5627190903300.904
Passenger side56271270902970.814

Our calculations reveal an average daily charge of 5.32 kWh if the Sion is left parked all day, facing north, on a perfectly flat street in Sante Fe, New Mexico (one of the sunniest places in the U.S.), without any shade. adequate to cover 24 miles.

But who actually uses their car in that manner? You want to operate the vehicle, correct? This calls for traveling in all different directions and parking in locations with shade, clouds, bird droppings on your car, and other features. On an average day in a sunny location, we estimate that you’ll only obtain around half that range from solar power.

Lightyear Automotive

Lightyear Automotive

The Lightyear One is a rival to Sono Motors’ Sion with a solar roof, although there are several significant distinctions between the two vehicles.

To begin with, the Lightyear One is now bookable for 150,000 Euro (about $170,000), more than five times the price of the Sion. More notably, the Lightyear One’s battery has a capacity of 60 kWh, which is slightly less than twice that of the Sion. However, thanks to the One’s svelte shape, it has nearly three times the range of the Sono.

Solar panels on the Lightyear One’s roof are stacked 5 square meters closer together than on the Sion. In essence, Lightyear appears to have fitted roughly the same amount of producing power as Sono, but only on the roof and hood.

Solar cells on the Lightyear One's hood

According to Lightyear, the One may go up to 12 km (7.46 mi) in range for every hour it is exposed to direct sunlight, which in most locations translates to an average of 30 miles each day. The enhanced efficiency of the Lightyear One makes it feasible that you may see that much production on a good day, even though we are just as dubious of that claim as we are of Sono’s.

What about Tesla?

Despite the fact that the firm itself produces solar cells and panels for use on homes, Tesla is renowned for its cars’ lack of solar roofs. Elon Musk, the CEO of Tesla, stated that a car is “the least efficient place to put solar” in 2017, and we tend to agree. However, there are many who would prefer a small increase in solar power. There are currently aftermarket components that can turn a Tesla’s roof into solar.

The final word on solar panel car roofs

You see, using solar panels on cars is simply not a good idea. We need them to be portable, move everywhere, and survive anything life throws at them, including the wind’s 60–80 mph gusts, boulders thrown up from the road, bird droppings, and extreme temperatures.

Why give yourself another excuse to hunt for the sunniest area when you already look for shady places to park your car? Our vehicles end up spending a lot of time in covered parking ramps and garages, which keeps them out of the sun.

You’re familiar with range phobia. How about the stress of needing to locate a sunny area simply to squeeze in a couple of miles on your way home? How far away from your final destination would you have to park to find that location?

We adore solar energy, but we also know that a home is the finest location for installation.