As population rises, fossil fuels will start depleting so are solar powered cars a good idea? How much power can they produce when it is cloudy?
A self-contained solar-powered car is not viable. There simply isn't enough area for the solar panels.
Take a Honda Civic as an example: it's got about eight square meters of top surface that solar panels could be installed on, for a peak theoretical generation of 8 kW. That same Honda Civic has a 92-kW engine, meaning that for each second of maximum power output, the car requires eleven and a half seconds of charging under ideal conditions.
Things look even worse once real-world constraints are factored in. The best solar cells ever built are only 47% efficient. Streamlining the car requires tilting the front and rear windscreens rather than leaving them vertical, which reduces the available panel area. The panels are rarely oriented square-on to the Sun. Solar panel output drops by about 20% over the useful life of the panel. All this adds up to an actual average power output of around 2.2 kW, or 42 seconds of charging per second of peak output.
Looking at it another way, one liter of gasoline has about 9.7 kWh of energy; an automobile engine can convert that into about 2.9 kWh of useful output. A solar Civic would need to spend 62 hours in direct sunlight to get the equivalent of a full tank of gas.