I’ll start with the bad news. . .
Throughout history, the United States has relied on a predominately coal based energy economy. As many people know, coal fired power plants are harmful to the environment and a catalyst for global warming. When coal is burned, greenhouse gases like carbon dioxide and nitrous oxide are released into the atmosphere. The pollution created from the burning of fossil fuels can have devastating effects on the local populations and environments where it is produced.
Now for the good news. . .
Over the course of the last year, the U.S. has consumed more energy from renewable, less harmful sources than coal. This is the first time this has happened in over 130 years!!
To celebrate this milestone in history, I want to take some time to explore the extremely cool science behind solar energy!
There are several different types of solar energy, but for the purposes of this blog I’ll be focusing on Photovoltaic solar – this is the type of solar that produces electricity we can use in our homes and businesses!
The energy in the PV solar process comes from, you guessed it, the sun!
When the energy from the sun reaches a photovoltaic cell, it can be converted into energy you can use in your home.
A photovoltaic cell is made up of a few different layers. The top layer is made of a protective glass, followed by a layer of conductive metal, 2 differing layers of silicon, and a conductive metal base.
The two different layers of silicon are called type N and type P silicon & this is where the magic happens. . .
To create the different types of silicon, the silicon is combined with different types of elements that give it an unbalanced structure. This unbalanced structure creates what are called “holes”. In P-type silicon the holes are positively charged and in N-type silicon these holes are negatively charged.
When these types of silicon are layered together, the holes line up forming an electric field, preventing movement of ions between the two layers (positive electrons stay in the P type silicon, negative in the N type)
When the sunlight hits these layers of silicon, it disrupts the bonds in both types of silicon, creating free roaming ions in both layers.
These two layers of silicon are sandwiched between two pieces of conductive metal, and the metal is connected with a circuit.
The circuit forces the excess ions and “holes” together, generating a direct electrical current (DC). This direct current (DC) is then forced through an inverter, that converts it to the alternating currents (AC) that we use in our homes!
For more information on electrical currents and solar energy, check out the resources below:
http://ewebpal.org/ (Semiconductor series)