Solar Photovoltaic Electrical Terms
Basic Solar Photovoltaic Electrical Terms that every solar technicians should know. Below are the basic electrical terms used in Electric Power(Solar) industry.
- Semi Conductors
- Potential difference and Volts
- Amperes and Current
- Ohms and Resistance
- Fuses and Circuit breakers
- Ohms law
- Power and Energy
- Direct Current (DC)
- Alternating Current
- Characteristics of Alternating Current
- Harmonic Distortion
- Power Factor
- Electric shock
A conductor is an object or type of material that allows the flow of an electrical current in one or more directions.Electrical current is generated by the flow of negatively charged electrons, positively charged holes, and positive or negative ions in some cases. Generally all metal are conductors with silver being the best conductor and copper in the second place.A good conductor allow an electric current(electrons) to flow from a source to load with least amount of resistance. The transmission lines and cables are now mostly Aluminium, which is slightly behind copper in conductivity but it is lighter and cheaper
An electrical insulator is a material whose internal electric charges(electrons) do not flow freely; very little electric current will flow through it under the influence of an electric field. Insulators resists the flow of electric current and are used to isolate electric current from areas which is not require.The property that distinguishes an insulator is its resistivity, insulators have higher resistivity than semiconductors or conductors.Materials like glass, paper and Teflon, which have high resistivity, are very good electrical insulators. A much larger class of materials, even though they may have lower bulk resistivity, are still good enough to prevent significant current from flowing at normally used voltages, and thus are employed as insulation for electrical wiring and cables. Examples include rubber-like polymers and most plastics.
Materials which are neither conductors nor insulators , but the exhibit some of the properties of both are called Semi-conductors.The material used in Solar cell is mostly silicon which is a semi-conductor. Other examples of semi-conductor are carbon,germanium, etc..
4.Potential Difference and Volts
Potential refers to the possibility of doing work. The difference in potential between two points that represents the work involved or the energy released in the transfer of a unit quantity of electricity from one point to the other.The difference between two charge points is called the Potential Difference(PD) and is measured in units called Volts.
Electric Current is the flow of electrons between two points and is measured in Amperes(A). When 1 Coulomb(6.27 x 1018 electrons) flow past a given point in 1 second , it is called 1 Ampere(A) of current.
When a potential difference causes a charge to move between two points, the charge in motion is called an Electric current(I). The number of electrons that can be forced to move depends on the potential difference between the two points. The greater the potential difference, the greater the current flow.
All electrons move with the same speed, only the quantity changes. So if the potential difference doubles, the quantity of electrons doubles, but the speed at which they travel is the same.Electrons flow from a negative terminal to a positive terminal . Conventional current flow, is in the direction of positive charge, i.e. the direction of current is reversed compared with the direction of flow of electrons in a conductor.
Conventional flow (flow of positive charges from positive to negative) is normally used to explain the operation of electrical and electronic, devices and circuits
6. Resistance and Ohms
Electrical resistance may be defined as the basic property of any substance due to which it opposes the flow of current through it. When a voltage is applied to a conductor,the temperature of the conductor will rise which is due to current flowing against opposition(resistance) in the conductor material.
Good conductors have very little resistance; insulators have very large value of resistance. The unit of measurement of resistance is Ohm(Ω).
To be Continued
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