How close are we to a solar powered car?

[DerGiLLster]

How close are we to a solar powered car? I mean a car that can depend on just solar power. Of course I don't believe we could ever create a car running on just solar power. I believe that a good car would be would be dual-receiving energy. One receiving electricity from solar and the other from it's own battery.

But really? How close are we to create a car that if was going to the Sahara could run more then 100mph, and just go on for hours as long as it received it's power from the sun? I know that we have created transparent solar panels which are terribly inefficient at about 1%,yet would provide more solar coverage of the car, but if it could reach efficiency at around 20% and a regular solar panel on the top of the car could receieve around 100%, would this be enough to power the car?

Also just to be more specific, the car would be a Tesla Model S with four people inside. Could it be done?

[sensij]

Could it be done?

No, not on earth, not in the way you are describing. Scroll down to the section about "power" in this wikipedia page about drag. A well designed car might need 60 kW of power to maintain 100 mph. The sun produces (roughly) 1000 W/m2 of irradiance. At 100% conversion (impossible), you would need 60 m2 of surface area exposed to the sun. That is roughly a 20 ft x 30 ft area. If your vehicle is that big, the drag will increase, and the whole thing spirals out of control.

[posplayr]

No, not on earth, not in the way you are describing. Scroll down to the section about "power" in this wikipedia page about drag. A well designed car might need 60 kW of power to maintain 100 mph. The sun produces (roughly) 1000 W/m2 of irradiance. At 100% conversion (impossible), you would need 60 m2 of surface area exposed to the sun. That is roughly a 20 ft x 30 ft area. If your vehicle is that big, the drag will increase, and the whole thing spirals out of control.

Power expended increases to the cubic power of velocity so there is some (low enough) velocity that it would work. Obviously to climb hills you need to reduce weight.

Solar racers are basically very light, lots of area and low drag.

https://en.wikipedia.org/wiki/Solar_car_racing

[J.P.M.]

How close are we to a solar powered car? I mean a car that can depend on just solar power. Of course I don't believe we could ever create a car running on just solar power. I believe that a good car would be would be dual-receiving energy. One receiving electricity from solar and the other from it's own battery.

But really? How close are we to create a car that if was going to the Sahara could run more then 100mph, and just go on for hours as long as it received it's power from the sun? I know that we have created transparent solar panels which are terribly inefficient at about 1%,yet would provide more solar coverage of the car, but if it could reach efficiency at around 20% and a regular solar panel on the top of the car could receieve around 100%, would this be enough to power the car?

Also just to be more specific, the car would be a Tesla Model S with four people inside. Could it be done?

As you seem to be defining "solar powered car", probably not using anything thought of as likely to happen in, maybe, the next 10 years or so. Once someone/group solves the electrical energy storage situation and manages to, say, get the same energy storage density, convenience, safety and public acceptance for electricity as for current petroleum based motor fuel schemes, the situation can change, but probably not as you envision them. Until then, stay tuned.

[UkiwiS]

How close are we to a solar powered car? I mean a car that can depend on just solar power. Of course I don't believe we could ever create a car running on just solar power. I believe that a good car would be would be dual-receiving energy. One receiving electricity from solar and the other from it's own battery.

But really? How close are we to create a car that if was going to the Sahara could run more then 100mph, and just go on for hours as long as it received it's power from the sun? I know that we have created transparent solar panels which are terribly inefficient at about 1%,yet would provide more solar coverage of the car, but if it could reach efficiency at around 20% and a regular solar panel on the top of the car could receieve around 100%, would this be enough to power the car?

Also just to be more specific, the car would be a Tesla Model S with four people inside. Could it be done?

Here's the way I think about this with some (almost) real life numbers.

I have PV panels on my roof and on a good day I can produce about 2 kWh per panel.

I also have a Kia Soul EV+. This car has a roof area approximately the size of a single PV panel...so on an average day if the roof was a Solar panel it would generate about 2 kWh. The car battery has a capacity of 27kWhs and a range of approximately 100 miles...fairly close to 4 miles per kWh. So to fully charge the battery would take 13 or 14 days. A full day of charging via the single panel on the roof would give about 8 miles of range.

[J.P.M.]

Here's the way I think about this with some (almost) real life numbers.

I have PV panels on my roof and on a good day I can produce about 2 kWh per panel.

I also have a Kia Soul EV+. This car has a roof area approximately the size of a single PV panel...so on an average day if the roof was a Solar panel it would generate about 2 kWh. The car battery has a capacity of 27kWhs and a range of approximately 100 miles...fairly close to 4 miles per kWh. So to fully charge the battery would take 13 or 14 days. A full day of charging via the single panel on the roof would give about 8 miles of range.

About 1-2 years ago Ford had what amounted to a publicity stunt with a Sunpower panel mounted on the roof of one of their vehicles. Folks on this forum came to about the same conclusions as to range and practicality as you. But, who knows what the future holds, except the promise of more promises for perpetual motion machines and the future equivalent of 200 MPG carburetors or solar powered airplanes you can park in your garage.

[DerGiLLster]

No, not on earth, not in the way you are describing. Scroll down to the section about "power" in this wikipedia page about drag. A well designed car might need 60 kW of power to maintain 100 mph. The sun produces (roughly) 1000 W/m2 of irradiance. At 100% conversion (impossible), you would need 60 m2 of surface area exposed to the sun. That is roughly a 20 ft x 30 ft area. If your vehicle is that big, the drag will increase, and the whole thing spirals out of control.

So basically it will never happen. At least cars won't be able to go fast while on solar power. So you are telling me there is a chance of solar powered cars being able to partially fuel a car going at 20-30mph and that's about it?

[sensij]

So basically it will never happen. At least cars won't be able to go fast while on solar power. So you are telling me there is a chance of solar powered cars being able to partially fuel a car going at 20-30mph and that's about it?

You got it. Speed record for those solar racers (in posplayr's wikipedia link) was ~50 mph averaged over 0.3 mi of distance (with no battery). They could go faster and farther on a single charge with a battery and no panels, but that isn't what you seem to be describing either. Increasing efficiency of panels will help, but seriously, what I think you are looking for is not physically possible.

More info on the record holding team is here.

[lkruper]

Here's the way I think about this with some (almost) real life numbers.

I have PV panels on my roof and on a good day I can produce about 2 kWh per panel.

I also have a Kia Soul EV+. This car has a roof area approximately the size of a single PV panel...so on an average day if the roof was a Solar panel it would generate about 2 kWh. The car battery has a capacity of 27kWhs and a range of approximately 100 miles...fairly close to 4 miles per kWh. So to fully charge the battery would take 13 or 14 days. A full day of charging via the single panel on the roof would give about 8 miles of range.

So, if one drives less than 2920 miles per year and less than 8 miles round trip per day, a solar powered car is feasible?

[posplayr]

You got it. Speed record for those solar racers (in posplayr's wikipedia link) was ~50 mph averaged over 0.3 mi of distance (with no battery). They could go faster and farther on a single charge with a battery and no panels, but that isn't what you seem to be describing either. Increasing efficiency of panels will help, but seriously, what I think you are looking for is not physically possible.

More info on the record holding team is here.

The Sunraycer was the first modern version of a solar car that won a race in 1987. I remember see it on display at the GM Delco Hughes plant I was working at back then. These solar races did not just pop up, the teams have been at it a while.

https://en.wikipedia.org/wiki/Sunraycer

The Sunraycer was a solar powered race car designed to compete in the world's first race featuring solar-powered cars. This race is now called the World Solar Challenge. The Sunraycer, a joint collaboration between General Motors, AeroVironment, and Hughes Aircraft, won the first race in 1987 by a huge margin.

[sensij]

So, if one drives less than 2920 miles per year and less than 8 miles round trip per day, a solar powered car is feasible?

As long as you can call in sick when it is cloudy.

[lkruper]

As long as you can call in sick when it is cloudy.

Or telecommute! The other think I was thinking about is that it is not necessary to have all the panels on the car for it to be solar powered. It can be parked in a car port with solar panels on the roof when it is not being driven.

[Sunking]

So basically it will never happen. At least cars won't be able to go fast while on solar power. So you are telling me there is a chance of solar powered cars being able to partially fuel a car going at 20-30mph and that's about it?

No very little chance ever. At least in any practical application with mass market appeal.

A top of the EV battery to wheel efficiency is roughly 300 to 400 watt hours per mile for a 3000 pound vehicle. As a rule of thumb you can figure 10 watt hours/mile for every 100 pounds of gross vehicle weight. Even if you had 100% efficient super light weight solar panels, mounted on a vehicle you are still only talking about 1/Kwy/day power generation. So for a 3000 pound vehicle 3 or 4 miles per day. Need to climb a hill, you had better plan on it taking a few days.

Physics is the obstacle you have to overcome.

[lkruper]

No very little chance ever. At least in any practical application with mass market appeal.

A top of the EV battery to wheel efficiency is roughly 300 to 400 watt hours per mile for a 3000 pound vehicle. As a rule of thumb you can figure 10 watt hours/mile for every 100 pounds of gross vehicle weight. Even if you had 100% efficient super light weight solar panels, mounted on a vehicle you are still only talking about 1/Kwy/day power generation. So for a 3000 pound vehicle 3 or 4 miles per day. Need to climb a hill, you had better plan on it taking a few days.

Physics is the obstacle you have to overcome.

OK, how about this. The road down from my cabin goes from 5500 ft to 1000 feet in 10 miles. Could the alternator charge the battery enough to get back up the hill?

[sensij]

My chevy spark ev is around 250 Wh / mi if i don't drive too fast on the highway, but that doesn't change your main point.