Thinking about zooming in our vehicles powered by pure sunlight sure sounds appealing, but the scientific calculations don’t really back this theory.
The sun is the closest thing we’ve found to a limitless source of energy. It bombards the Earth with enough energy to power a year’s worth of human electric activity in just over an hour. It won’t run out for billions of years, it doesn’t pollute our atmosphere, and it can be accessed from anywhere. You’d be forgiven for thinking it’s the perfect solution to powering our cars.
We’re not wrong to assume that solar energy is the most effective energy source available to us. It is capable of powering all our electric activity in over an hour of sunlight rays. It won’t burn out and is the best possible solution for our climate as it does not create any pollution. But what’s the problem, you may ask?
Car manufacturers and researchers have used billions of dollars to create hydrogen and electric cars, but none has created a vehicle powered by solar energy. Why is that the case, you ask? Engineering Explained demonstrates in his latest video that the reason behind this is that a car-sized solar panel can only absorb a restricted amount of solar energy, which isn’t enough for powering it.
If we calculate the total amount of solar energy the Earth gets from the sun, we can conclude the average per square meter of energy received. By utilizing that number, we find that a solar panel equivalent to the size of a Tesla-Model-3 would, in theory, receive 12-KW-equals 16hp from the sun. That amount of power enables it to cruise at 62mph without the further requirement to recharge.
But it’s not that simple in real life. Only 55% of the sunlight that is reflected reaches the Earth’s ground. That too only during daytime especially at noon. Off-angle sunlight available in the mornings and evenings further restricts the amount of solar energy absorbed.
We have further technological restrictions as well. If a single ample-sized panel is manufactured, it will still be capable of absorbing only 33.7 % of solar energy that can be further turned into electricity. The car is comprised of non-solar paneled surfaces like windows etc. which limits the solar energy absorption. This results in the car getting enough energy to move at a maximum of 12mph which does not include it being able to accelerate, which requires more energy.
If the Tesla Model 3 is stationary for 8.3 days (200 hours), it will absorb enough energy to charge its 75kWh battery fully. However, given perfect weather conditions and an ideally sized solar panel, these results still lack accuracy.