It is Free Energy...
Most types of renewable energy is free. They are already there and just needs a system to harvest that power. For Wind energy, we use wind turbines. Also, for water we use turbines. But for solar collection, there are many types of collectors and most of all, it is one of the cleanest and most abundant source of free energy. Due to advances in solar technology, there are many ways to harness solar energy. The oldest of which is lighting. Yet the newer forms include turning solar energy into electricity (PV or photovoltaic), Heating and cooling (Solar Thermal) and concentration of solar power for utilities.
There are two types of solar energy, active and passive. Active solar energy is the changing of the light into energy. Therefore the PV and solar thermal systems are forms of active energy. The concentration and heating or cooling systems would be considered passive solar.
Passive solar is not just systems but it is the incorporation of design and planning to harness the sun’s energy. This could be so for lighting and even heating in some places. Not only is passive solar used for taking advantage of the sun’s energy, but to protect the buildings from excessive heat for cooling. Lastly, solar energy systems are both business and personal consumer friendly. There are various types of systems from permanent mounted systems smaller portable systems.