How Solar Energy Works
There are basically two techniques for using solar energy (passive and active).
- Passive Solar Energy – Refers to techniques that convert sunlight into useful energy (i.e. sunlight to warm house or dry clothes) without the use of mechanical or electrical systems.
- Active Solar Energy – Refers to techniques that convert sunlight into useful energy using mechanical and electrical systems. Solar Photovoltaic (PV) systems use this active method.
Photovoltaic (PV) is a word that describes converting sunlight into electricity: (photo) meaning pertaining to light (voltaic) meaning producing voltage. Electricity is the existence (either static or flowing) of negatively charged particles called electrons.
Certain materials called semi-conductors (i.e. silicon which is a semi-conductor and the main material in 98% of solar PV cells today) can be adapted to release electrons when they are exposed to sunlight.
All solar PV cells have at least two layers of such semi-conductors (silicon) one positively charged and one negatively charged. When the sunlight shines on the solar PV panel semi-conductor material (silicon), electrons are released from their atoms (this is called the “Photoelectric Effect”). These free electrons then travel into a circuit built into the solar cell to form electrical current.
The individual solar PV cells are interconnected together to form a PV MODULE and multiple PV Modules are connected to form a PV ARRAY mounted either on the roof or the ground. The electricity produced from solar PV cells is in the form of Direct Current (DC). The (DC) output then goes to the INVERTER which converts the current into Alternating Current (AC). The (AC) output is then usable in our buildings, houses or elsewhere on the utility grid. Any excess (AC) output can either be fed to a BATTERY BACK UP (optional) or to the utility grid in a process called NET METERING.
Basically with Net Metering the utility grid acts like a bank (when you have excess power, it is deposited to the utility grid, spinning the meter backwards) and when you need more power than your Solar PV system is producing (the meter spins forward) sending you power back from the utility grid.