Photovoltaic (solar) cells work in a fundamentally different manner than other forms of energy production. Although the basic notion is the same (i.e. take one form of energy and transform it into another), the process is radically different than turbine-based energy.
Solar Cells: the Inner Workings
A solar cell converts the energy of a photon (a light particle) into electricity. Again, we may think back to high school chemistry class and think about molecules, or atoms in this case, with electrons spinning around them like a cloud. In a solar cell, the particular chemical is an element, namely, silicone. The basis of a solar cell is silicone laid out in a long array. Every atom wants to have 8 electrons in its outside shell, and each atom of silicone has four. Thus, each silicone atom shares its space with four other silicone atoms.
The Catch!
This structure of silicone laid out in an array is lovely and all, but there’s one big problem- it has no electrical charge. When all the atoms bind together, they create a crystal lattice structure that is electrically neutral.
The Fix!
In order to make a silicone array conduct electricity, three things must be added.
- A positively charged element
- A negatively charged element
- Electrical conductors
These first two are really impurities, but it creates a VERY important phenomenon. While the silicone lattice creates a good structure for the electrical circuit, the impurities create a space in which electricity can be generated.
So say we have an impurity that needs one electron and another that has one extra electron (i.e. one column to the right and one column to the left on the periodic table). Now we put them on the crystal lattice and a space is created. That space is the area in which one atom wants and electron and one atom wants to give it away. It is here that solar energy is created.
The Actual Process
Once we have a space created in which energy can be produced, there is one more problem- atom’s will generally hold onto their electrons. Thus, energy has to be pu into the system. This is where the sun comes in! A photon of the correct energy must hit that electron that wants to escape and cause it to become excited, destabilizing it. It then jumps from hole to hole till it reaches the electrical wires on the end. From there, it goes to your house, the grid, or wherever else you may send it. It’s a truly elegant process if one considers how simply an electron is moved, taking the sun and turning into pure electricity.
The Bottom Line
If chemistry is not your strong point- or bores you to the point that you could use this article as a sleep aid- take this as the central lesson. Energy from the sun excites electrons. These electrons move along the cells where they end up as electricity (which is just a stream of electrons). Connect it to an electrical system and voi la! You have electricity.
And there is a key point for everyone. No electrical system can function if it is not a circuit. Thus, there must be a way for that electron to make it back to the array. Hence why all solar cells are tied in circles. When an electron arrives back at the beginning, the process can begin anew.
