Solar Photovoltaic panels are made out of sand that is converted to silicon. Sand converted to silicon is cut into layers known as solar cell wafers. Chemical impurity elements such as boron and phosphor ions are added to these silicon wafers. These impurity elements enhance the electrical production properties of the silicon wafer when exposed to sunlight or rays.
Each added element has a property of being positively or negatively charged, the wafers are known as p-type silicon and n-type silicon respectively. One negatively charged wafer layer is placed on top of a positively charged wafer layer. The area between the two is known as the wafer junction as seen in the diagram below.
|Silicon - Solar Photovoltaic Solar Panel Diagram|
|Silicon Wafer - Solar Photovoltaic Component Diagram|
How do Solar Panels Generate Electric Power:
Solar panels generate electric power (current & voltage) when they are exposed to sunlight rays. When light rays strike the top silicon wafer, electric current is produced between the two silicon wafers and a negatively charged voltage is created on top of the layer. Usually, small mesh copper contacts are placed on top of the upper silicon layer as seen in the diagram above.
The copper mesh allows sunlight to penetrate to the silicon layer below it. The copper mesh draws the negative electric charge produced from the upper silicon layer and a negative voltage is created.
The bottom silicon layer is joined to a solid copper sheet at the bottom. Since a negative electric charge is created on the upper wafer layer, the bottom wafer layer becomes positively charged. The positively charged layer is connected at the bottom to the metal copper sheet.
The copper sheet is connected to the other lead of the electric circuit. The current produced between the top and bottom layers flows in the electric wires to power electric devices that uses direct current similar to battery powered electrical devices or stored in batteries. Later inverters are used to convert power stored in batteries to utility electric power for various uses.
Temperature Effect on Solar Photovoltaic Panels:
One thing to note about solar photovoltaic panels is that they are sensitive to varying temperatures. Temperature effect solar panel output power. And increase in temperature above 25 degrees Celsius would require compensation during site design. This would insure that the output power is able to charge the batteries or feed the designated load. Usually, solar system design engineers have many criteria to consider during initial site evaluation besides temperature.
Temperature has an effect on the output power of a solar photovoltaic panel. The panel is naturally dark. When exposed to sunlight rays, its temperature will increase. At temperatures below 25 degrees, there is little effect on output power; actually it is to the benefit of the output power. A positive gain of about 5% would be expected at zero degrees Celsius.
However, at temperatures higher than 25 degrees C, the power output would drop down. This effect can be as much as 20-30% if not higher (dependent on location and other factors). Usually the manufacturer’s data sheets should display a graph as to how temperature change influences the output power of the solar photovoltaic panel system.
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