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Sunlight is made up of tiny energy packets called photons. It is estimated that every minute enough of this energy reaches the surface of the planet to meet the energy demands of the whole world for an entire year. Photovoltaics is the science of capturing and converting this energy into electricity. Photoelectric panels consist of many individual solar cells connected in series. These panels are made of materials like silicon, one of the most common elements on earth. The individual cell is designed with a positive and a negative layer, just like in a battery, that overlap other cells to create an electric field between multiple cells. As photons are absorbed in the cell, their energy causes electrons in the cell to be knocked loose. The electrons then move toward the bottom layer of the cell and exit through a conductive layer to connecting wires. This flow of electrons is what is called electricity. By first combining solar cells to create panels and panels to create photovoltaic arrays, we can produce just the right amount of electricity to perform a specific job, no matter how large.
The performance of a solar cell is measured in terms of how much of the sun’s energy striking the solar cell is converted into electrical energy. Early versions of solar cells used crystallized silicon wafers that are very costly to manufacture and operate at as high as 20% efficiency. That means that, about 1/5 th of the energy striking the cell is converted to electrical energy. Today, the most common and commercially viable solar cell uses a manufacturing process similar to those used in semi-conductor manufacturing. Micro layers of amorphous silicon are built-up to produce thin film cell structures averaging 7% to 14% efficiency rates. These solar cells are typically opaque, are architecturally limiting, and usually are placed in confined and limited areas, such as roof tops, and continue to average more than double the cost per kilowatt hour compared to power costs from your local electric company.
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