Henry Dover answers:

They’re already considering using satellites, but not in that way.

They’re thinking of using satellites equipped with thin film solar cells to generate electricity that is then beamed down to receivers on Earth using microwaves.

This is probably more sensible than just using mirrors when you consider that mirrors reflect visible light (and I’m not sure what their full wavelength response will be either…), which can be blocked by clouds.

Thin film solar panels aren’t much heavier than mirrors anyway (the ones we make in my lab are 2-3mm of glass, the solar cell itself is about a thousand times thinner and stuck to the back), and by converting to microwaves, you can beam the power back down regardless of whether it’s cloudy or not!

Wiki has a page:

http://en.wikipedia.org/wiki/Space-based_solar_power

Japan are talking about putting one in orbit by about 2030 iirc!

Henry Dover answers:

Solar or light can be converted into current and batteries can be made at a smaller scale. Example is, small calculators are powered by solar cells.

As for as construction of those batteries they are made of smaller cells and then smaller cells are joint with other smaller cells to make little large cells. Its very expensive to make them on commercial level thats why we are addicted to oil.

Cheap things sometimes don’t come cheap.

Henry Dover answers:

It depends on how big the car is, but in general the answer ends up being “not much”. There’s about one kilowatt, a bit more than a horsepower, per square meter of sunlight in good sunny conditions with the sun close to directly overhead. Current common solar cells have a conversion rate of about 15%, as you said. So, if a car is two meters wide, and three meters long, this will get you 600 watts, about 8/10ths of a horsepower, under ideal conditions. These conditions are that the sky is clear and the sun is close to directly overhead, and so on.

As far as how advanced solar cells will change this, the best available now are around 35% efficient. These are intended for space use where every little bit of weight savings counts, and are much, much more expensive than conventional solar cells. Use of these would get you over 1.5 horsepower under ideal conditions. The maximum, assuming hypothetical 100% efficient solar cells, something we have no idea how to make currently, and which will probably never be possible, would, like I said, be about 1kW per square meter of car space, again assuming ideal conditions.

It is possible to make a solar powered car that is fully driveable and can cover a good distance, but it’s going to have to be very lightweight, very aerodynamic, and have an extremely low rolling resistance if it’s to have anything resembling reasonable acceleration and top speed.

Henry Dover answers:

It isn’t a matter of expense, it’s a matter of physics – solar energy at noon on a bright clear day at middle lattitudes is only about 100 watts per square meter. One horsepower is 755 watts, and an average car has a top surface area of maybe 7.5 square meters, so there’s only about 750 watts or 1 horsepower available from the sun. 1 HP is nowhere near enough power to accelerate a 1-ton car at a reasonable rate, and top speed would be maybe 10 or 15 mph, if very skinny high-pressure tires were used. But it’s even worse than that – the best (and most expensive) solar panels available right now, like used in satellites and the ISS are only about 30% efficient. So your car is now down to 0.3HP.

Money is not the problem.

[REPOST]

Storing the energy in batteries, huh? Okay, then this car will need to be exposed to 25 hours of bright midday sunlight in order to have enough energy to supply 15 minutes of 30 horsepower.

Henry Dover answers:

12:00:00 will last about 5 days with out stoping and at lest 3 square meters is needed