After all, the energy source (sunlight) is reliable, locally available, and always free. In fact, did you know that in roughly 40 minutes, the sun sends to the earth's surface about as much energy as the earth’s population would use in a year?

How does it work? 

A solar electric system has just a few components — photovoltaic (PV) panels (they collect the sun), and an inverter (a power unit). Your solar  system is connected to the local utility grid, which stores the solar power you generate.

During the day, the photovoltaic panels capture the sunlight … and the inverter converts it to usable electricity.  The energy you produce on any given day, and that you don’t use, goes back to the utility grid.  At night, or when the sun isn’t shining, you will use  electricity from the connected utility.  Depending on where you live, the utility company may be required to credit you for the amount of electricity your system contributes to the grid at the retail value of the electricity at the time it was generated.  By properly sizing your solar system to cover your electricity usage, you can reduce or even eliminate your utility bill.

In solar thermal applications, where you’re heating water, it’s just as simple.  A solar collector plate is positioned to face the sun, where it catches and absorbs the sun’s heat.  A fluid (water or glycol) flows through the piping within the collector.  Behind the insulated plate is an air gap, which allows excess heat to be released, preventing stagnation and overheating. As heat is collected, it’s transferred to your household water tank through a heat exchange process.