Home Solar Energy Systems and the Photoelectric Effect (part 9)


In the article that follows, we will explain in how a residential solar (PV) cell converts photons of sunlight into household electrical currents. This process is called the photoelectric effect. We will also explain the physical characteristics of how silicon moves electrons through various states to produce household solar electric power.



Einstein was awarded the Nobel Prize in Physics for his work on the photoelectric effect, not for his work on relativity. Little did one know that the same people who helped us calculate everything under the sun is also the same person helping to bring renewable solar energy to the masses.



Solar Electricity and the Photoelectric Effect



The photoelectric effect is a key concept, since it is the way sunlight is converted into free electrons as light interacts with the solar cell. Without the creative work of Albert Einstein, the physical characteristics of sunlight might not be known. Never mind the impact and Earth-altering opportunities to power your home using solar generated electricity that his ideas inspired all these years later.



Think of sunlight not as a wave but as a beam of photon particles for the purposes of explain the technical details of how home solar energy systems work. These bundles of energy penetrate the silicon lattice structure inside the solar cells making up a home solar panel and transfer their energy to an electron in the outer layer of the silicon atom.



When a single electron gains enough energy from the penetrating photons, it breaks free and floats around the lattice structure, no longer bonded. An electron has a negative charge when it is knocked free during the photoelectric effect. The silicon atom that loses the electron, which had a neutral charge with the electron, now has a positive charge without it. Remember back to high school chemistry. Suddenly, these classes seem relevant when learning about solar generated electricity. Who would have known?



When an electron is removed from this lattice structure or matrix in this fashion, it creates a hole in the outer layer of the lattice where the electron was. A nearby electron with a negative charge soon fills the hole. The electron that moves in has a positive charge. It can be described like the balancing of an equation; i.e. when one silicon electron consisting of a negative charge is transferred in...another particle, in this case an electron with a positive charge, is bumped out and moves out.



As photons of sunlight penetrate the silicon and knock electrons loose they transfer their energy. Negative electrons are forced to move into nearby holes and positive holes appear where electrons once were. This photoelectric effect works because of the one-directional flow of positive and negative electrons. This flow of electrons produces the electrical current used in everyday use. The one way or single direction that the silicon electrons is produced when the sunlight, which is really photons of energy, repeatedly hit the silicon solar cells inside the PV panels making up the home solar power unit.



Incredibly enough, this process is the secret sauce that allows electricity to be produced from ordinary sunlight. It is Albert Einstein's discovery, called the photoelectric effect, that makes solar electric energy possible. The average homeowner can now buy or rental home solar energy systems and generate useful electricity for their house.


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