As a PV designer and installer, you should be perfectly familiar with the following basic electricity concepts:
Current is the flow of electrons through a conductor (wire). The SI unit of current is ampere (A).
Current is the flow of electrons through a conductor (wire). The SI unit of current is ampere (A).
Ampere represents a flow or rate of electrons movement.
The base unit of ampere is coulombs per second.
In Direct Current (DC) electrons flow in one direction.
In Alternating Current (AC) electrons flow in a back-and-forth pattern.
AC differs from DC mainly in the sense that the current/voltage alternates in flow at a specific interval of time.
Ammeter are used to measure electrical current (AC and DC both). Two commonly used types of hand-held ammeters are:
- Inline Ammeter requires current to flow through the meter in order to be measured.
- Clamp Ammeter have a jaw on the top that opens when you press a lever on the side of the meter. To measure current you have to place conductor inside the jaw.
Voltage is an electrical pressure that encourages electrons to flow in the conductor.
Nominal Voltage is a number that represents a baseline for measuring voltage.
Operating Voltage is the output voltage.
SI units of voltage is Volt (V).
To measure voltage you can use Digital Multimeter (DMM) which is a third type of hand-held measuring device.
Resistance is the opposition of flow of DC current.
To measure voltage you can use Digital Multimeter (DMM) which is a third type of hand-held measuring device.
Resistance is the opposition of flow of DC current.
Impedance is the opposition of flow of AC current.
SI unit of resistance/impedance is ohms.
Ohm's Law can be stated as:
Voltage = Current x Resistance
Power is the measurement of flow of energy. It is a rate and an instantaneous value.
SI unit of power is Watts (W).
One watt is equal to one joule of energy per second.
1000 Watts = 1 kilowatt (kW).
Energy is the measurement of power multiplied by time.
It is measured in kilowatt-hours (kWh). (It is not SI unit.)
kWh is the number on the basis of that your utility provider charges electricity bill.
Energy in (kWh) = Power in (kW) x Number of hours (h)
Ampere Hour (Ah) is the unit of electric charge. Ah is commonly used for batteries.
Charge in (Ah) = Current in (A) x Number of hours (h)
1Ah = A x 3600s = C/s x 3600s = 3600C
A collection of 6.24x10e18 electrons has a charge of 1C (one coulomb).
Ampere-hours (Ah) = Watt-hours (Wh) / Voltage (V)
Series
connections are made by connecting the positive wire from one module to
the negative wire of the next module. In series connection, the voltage
values are additive and current values remain the same.
Parallel connections are made by connecting the positive wire from one module to the positive wire from next module and the negative wires are connected together. In parallel connections, the current values are additive and the voltage values remain the same.
Combination of series and parallel connections can be made to obtain the desired value of voltage and current.
Parallel connections are made by connecting the positive wire from one module to the positive wire from next module and the negative wires are connected together. In parallel connections, the current values are additive and the voltage values remain the same.
Combination of series and parallel connections can be made to obtain the desired value of voltage and current.
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