Solar PV Systems Explained
A solar PV system absorbs the sun’s energy through photovoltaic (PV) cells. The word “photo” refers to light and “voltaic” refers to electricity. This is the type of cells used in satellites and solar calculators. A group of photovoltaic cells is called a solar module. Modules are electrically connected to make a single frame. PV cells consist of semiconductors that convert energy into electric current.
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Process
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When sunlight reaches the cell surface of a solar PV system, a portion of this light energy is absorbed by semiconducting materials arranged in layers. This energy loosens the electrons in the semiconductors. The PV cells also create an electrical field that allows these electrons to move in a particular direction. The electrons’ flow is a current. This current is drawn out by metal contacts placed on the top and bottom of the PV cells. Such current and the PV cells’ voltage created from the electric field form the cell’s power. This power is defined in terms of kilowatt peak (kWp).
Categories
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The two main categories for PV semiconductors are crystalline silicon and amorphous silicon. A crystalline solar cell's top layer is enveloped with tempered glass while its back is covered by tough material called tough ethylene vinyl acetate (EVA). These materials are designed to protect PV cells from moisture. Monocrystalline is the most effective crystalline silicon and is made from slices of huge single crystal ingot. Amorphous silicon originated from thin film technologies. Amorphous silicon cells are easier to assemble and they can be used with low cost building materials such as plastic or glass. However, it is generally less efficient than crystalline modules.
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Installation
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The roof is the usual spot to put up a PV system because it’s directly exposed to sunlight. However, not all roofs have the right orientation or inclination to maximize absorption of sunlight. PV systems located in the Northern Hemisphere must face south. The system must be angled according to the area’s latitude for optimal absorption throughout the year. PV systems can be positioned on the ground or mounted on a wall as long as they are not under the shade of trees and buildings. For systems of 1 kWp, you can install a maximum power-point tracker. This device controls and ensures maximum sun energy transfer.
Benefits
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Solar PV systems save energy and lower electric bills. Most home PV systems do not require too much installation space. It does not emit carbon dioxide or other harmful pollutants. A solar system can increase the value of a home. It can be used as an incentive for prospective buyers as they will have lower power costs.
Considerations
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Before installing a solar PV system at home, consider the amount of sunlight that your house is exposed to as well as its location. You should also determine the amount of energy being used every day. This amount should be compared to the cost of installing a solar power system. The roof of the house should have enough space to accommodate the system and its material should also be strong enough to support such a system.
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References
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- Photo Credit Solar Panels image by alessbonaventura from Fotolia.com
