How Photovoltaic Solar Technology WorksInternal View of a PV Cell [1]
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Photovoltaic cells (PV) are the current technology used in the solar industry on panels, referred to as PV arrays. A basic PV cell consists of a thin layer of phosphorous-doped (N-type) silicon on top of a thicker layer of boron-doped (P-type) silicon. Doping in terms of a semi-conductor is the process to intentionally manipulate the electrical properties. In the case of phosphorous-doped silicon, the N-type refers to the manipulation to make the charge of the silicon negative, and vice versa for the boron-doped silicon P-type. The resulting connection between the two layers of silicon is an electric field known as the P-N Junction. When photons from daylight strike this surface, the electric field directs the light, creating a current when the PV cell is connected to an electrical load [1]. |
How a Photovoltaic System WorksFundamentally, a PV solar system is similar to any other electrical power generating system, the principal difference is the equipment used in the system. Once the current is generated from the light striking the surface of the PV array, the current is carried to an inverter, where it is changed from direct current (DC) to alternating current (AC). Then, the current can be carried to an energy storage battery bank, and or an energy distributor which facilitates the energy to an electrical utility[2].
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Basic PV System Schematic [4]
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Types of PV SystemsGrid-Connected SystemThere are two main types of PV systems, grid-connected and stand alone systems. The idea of the PV systems design is to be able to provide DC and or AC power, and to operate interconnected with, or independent of the utility grid. The primary difference in the two systems design is the battery storage bank. In a grid-connected system, the PV array is converted to grid-friendly power through a distribution panel which has a two way interface. This means the utility can send AC power to the distribution panel, and the PV array can send AC power to the utility. The distribution panel feeds the grid when the output is greater than the demand of the entity being powered by the PV array [3].
Stand Alone SystemThe alternate type of PV system, stand alone system uses a battery storage bank in place of the distribution panel. The objective would be to store the power when the PV array is not operating, such as during the night. Only in certain circumstances where there is policy in place for the consumer to be able to sell power to the utility do stand alone systems have a distribution panel, otherwise the power of the PV array is solely used on that particular entity, and excess output is stored in the battery bank [3].
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Grid Connected System Schematic [4]
Stand Alone System Schematic [4]
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