Power stations rely on some source of energy to get the generators that produce the electricity to turn.  The traditional fuel that has been used is coal and natural gas, largely still being used today.  Other methods, of later incorporation, were harnessing the power of running water (hydroelectric power) and having huge wind mills catch the blowing wind (air power). 

Solar cells are a series of photovoltaic cells that, upon stimulation from the sunlight, cause a transfer of electrons to take place.  Solar energy replaces the need to burn fossil fuels, depleting our Earth of valuable nonrenewable resources.  The drawbacks of solar energy are the expense involved in the production of solar panels and the fact that not every day is a "sunny" day.