Solar Photovoltaic (PV) - How Solar PV Actually Works
Solar Photovoltaic / Photo (Light) + Voltaic (Electricity)
Simply Put, Getting Electric Power from the Sun's Light
Solar Photovoltaic (PV) cells change sunlight directly into electricity. Solar cells are often made from silicon-based materials that react to the suns light not it's warmth (as Solar Thermal panels do). Certain types of materials called semiconductors convert sunlight to electricity naturally. In a Solar PV cell the sun's photons strike a thin silicon layer which dislodges electrons in the thin semiconductor coating creating a flow of electrons which is electric current. A Solar module contains many solar cells connected together. Several solar modules (solar panels) form a solar array which directs output all of the solar electrical energy to your inverter.
The solar electric energy created is in the form of direct current (DC) power. This power is routed to an inverter that converts it to alternating current (AC) for use in your home or business. The power flow also will be tied into your electric meter and to the grid. This will allow you to move power you don't use to the grid (getting paid for it by the utility) and to tap into the utility when you need to supplement your own solar power generation. Grid tied inverters are designed to shut down transfer of electricity to the grid automatically during a power outage. This built-in feature is to protect any line workers that may be working during the outage. Battery based inverters can allow continued use of your solar power during the outage after disconnecting from the grid. They reactivate the output in a split second to continue supplying electricity to any loads wired into the critical load sub-panel.
Well over fifty years ago, scientists at Bell Laboratories unveiled the first modern solar cell, using a silicon semiconductor to convert light into electricity. Solar was envisioned by Bell as a way to power the phone calls of the future.
Today there are two main types of silicon based solar panels on the market that offer varying costs, efficiency and longevity of use. The most effective at converting sunlight to solar power are the Monocrystalline type which convert about 18 percent of sunlight to electricity. They have a lifespan of twenty five years or more and are the most costly of the solar cells. The next most efficient type is the Polycrystalline variety which converts only slightly less sunlight to energy at a rate of about 15 percent. These solar panels are less expensive and have a comparable lifespan. These are the most commonly used Solar PV modules and solar panels today.
There are also thin film Solar PV cells made Amorphous Silicon or from Cadmium Telluride based materials. These thin film cells can be produced at lower costs but also have lower efficiency and a shorter lifespan as well. These cells can be manufactured easier and are being used in many large scale solar installations. Cadmium is toxic so there are environmental considerations to be factored in as well.
Newer technologies are adding these thin film PV materials to rooftop shingles, tiles and other building materials. These solar materials work in very thin layers and can even be "printed on" substrates of many kinds for use in electric power generation.