Scientists are still experimenting with solar cells to find the perfect solution. The Greeks and Roman started using solar energy and one day hopefully most of the energy produced in the world will be from the sun. Every day the sun showers Earth with several thousand times as much energy as we use. Even the small amount that strikes our roof is many times as much as all the energy that comes in through electric wires. With the sun straight overhead, a single acre of land receives some four thousand horsepower, about equivalent to a large railroad locomotive. In less than three days the solar energy reaching Earth more than matches the estimated total of all the fossil fuels on Earth!
