The term solar panel is used to describe two completely different technologies, both of which generate energy from sunlight, and both of which are packaged in the form of panels:

• a photovoltaic module is used to generate electricity
• a solar thermal collector is used to generate heat (generally hot water)

Solar Cells
A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the light source is unspecified. The field of research related to solar cells is known as photo voltaics.
Solar electric panels contain many photovoltaic cells electrically connected and packaged behind glass for mechanical protection and electrical insulation. The modules are usually connected together in an array and with other components such as a mounting frame and an electrical inverter (for on grid) or a charge controller and batteries (for off grid).

In addition to solar panels, a photovoltaic (PV) system requires a mounting structure to tilt panels toward the sun, an inverter to convert panel-generated direct current (DC) into appliance-friendly alternating current (AC), battery storage to compensate for unfavorable weather conditions, and a charge controller to regulate battery operation.

Hybrid Systems
In Hybrid Power Systems the power is generated from a combination of power sources such as solar PV, wind generator, hydro generators and may use a LPG, petrol or diesel generator when the renewable energy generator is not meeting the power demand.