eventually cars will be covered in solar panels so you just charge as you drive and wherever you are parked. that will be sweet. road trip? Just go when it's sunny and run forever.
That will never be possible. The ratio of the car's surface area to the amount of energy it requires is too low. Even if you had a car that used the same amount of energy as a Geo Metro or large motorcycle but had the surface area of a tour bus and was completely covered in 100% efficient solar panels, it still wouldn't be enough.
Jack, never say never!
Normal maximal solar irradiation on earth is about 1000 watt per square meter. A 100% efficient panel would therefore generate as much power.
According to this study (www.mdpi.com/1996-1073/7/12/8317/pdf), the 800 KG passenger car that they modeled consumes about 2,250 watts driving at 50 Km/h per hour. It would totally be possible to drive that car at that speed using 100% efficient solar panels on the car (assuming optimal sunlight).
So yeah, when you factor in efficiency and non optimal conditions, it likely won't be possible with current technology but solar panels could still contribute a non trivial amount of energy to a car and possibly extend the range significantly.
800 kg is 1764 lbs, or slightly heavier than a 1990 Geo Metro (and lighter than even a Mazda Miata). And that's before you add any passengers or cargo. And don't forget range issues! You'd still need batteries for our hypothetical car (in order to do things like drive at night), and those still add weight. Let's assume a realistic minimum laden weight is more like 2600 lbs, or about 1.5x the car in the study. Power required increases linearly with mass, so a car weighing 1.5x more would need 1.5x more power.
50 km/h is 31 mph, or about half as fast as the car would need to go to keep up with normal traffic. Note that the power required to overcome drag increases with the cube of the velocity, which means that the power required to go 60 mph is 8x more than the power required to go 30 mph.
If we multiply the weight and drag factors together (which is a wild and reckless simplification, but probably good enough for a forum post), it seems like we need 12x as much power than the study assumes, which means we'd need 12x as much surface area for the solar panels. The car in the study actually needed 2250 watts and you assumed the panels produced 1000 watts per m
2, so it would need 2.25 m
2 and our realistic car would need 27m
2A Cadillac Fleetwood, one of the largest sedans ever made, measured 78" wide and 225" long. Translated to metric, that's roughly 2m * 5.7m = 11.4m
2 of projected surface area -- not enough, even before you subtract to account for things like the sloping windshield and the fact that no realistic car would be perfectly flat and rectangular.
Jack, never say never!
Normal maximal solar irradiation on earth is about 1000 watt per square meter. A 100% efficient panel would therefore generate as much power.
I suppose if we repealed the first two laws of thermodynamics you could be right....
What laws of thermodynamics is he breaking? Non engineer here, so not attacking.
The first and second laws, as the GP stated. They can basically be summed up as "100% efficiency is impossible."