ELECTRIC ESSENTIALS AND RELATIONSHIPS IN SOLAR PANELS
Next essentials are important for understanding solar technology:
Electricity is a form of energy that can be carried by wires and is used for heating and lighting, and to provide power for machines.
- Electric current is the most essential quantity in electricity and produces all wanted effects possible with electric energy. Electric current is a stream of negative charged electrons.
- Electric voltage is the pressure for moving electrons forming electric current. The higher pressure the greater current.
- Resistance is the obstructing factor on the current through an electric circuit. The effect of the resistance must be broken by increasing the voltage in order to remain the wanted current.
Summarizing it is said electric current is needed for a certain effect and voltage is used to maintain the current in a circuit with a load. In the load the electric effect takes place.
The symbol for voltage is E (Electrical pressure) or U.
Voltage is measured in volts, V for short.
The symbol for current is I (Intensity of current).
Current is measured in amperes, A for short.
The symbol for resistance is R (Resistance).
Resistance is measured in Ohms (name of a physicist), or E (Entity) for short.
5.1 CURRENT DELIVERY AND ENERGY CONSUMPTION
In general the sectional plane surface of a current-conductor highly defines the resistance in a flow process.
E.g. for a liquid the diameter of a conveyer tube is essential for the extent of current obstruction. There is less resistance with a bigger surface. Same is due for the cross section of a copper wire for the current flow in an electric circuit. There is a greater resistance with a smaller diameter. So the acceptable current in an electric circuit is primarily defined in the cross section of the wires.
The current delivery in a certain time is limited. The delivery amount is measured in so called “ampere hours”, Ah for short.
The amount of current with an intensity of 1 A flowing in a conductor during a time of 1 hour is called 1 Ah.
These current can be delivered by a battery (accu = accumulator).
The capacity of a battery is specified in the indication ampere-hours. The capacity of a battery defines the amount of current that can be delivered in a certain time. So there is a one to one relationship between the energy need in a certain time and the capacity of the accumulator. Finally the battery defines the amount of energy that can be delivered. In what time span this happens, depend on the combination of the overall current and voltage values in that period. That combination defines the amount of delivered energy representing a certain power. Electric power is measured in watts, W for short
A watt is a unit of measurement of electrical power and is equivalent to the power in a current of 1 A by a voltage of 1 V. Watts give an indication of the energy consumption of a device. When power is coupled to time, the amount of delivered energy can be defined.
The unity of delivered energy is the watt-hour, Wh for short.
A device is consuming an energy amount of 1 Wh, when during 1 hour an amount of energy is consumed of 1 W.
5.2 DC FORMULAE
Voltage = Current x Resistance
Power = Voltage x Current 1000W = 1 Kilowatt (kW).
Energy = Power x Time 1000Wh = 1 Kilowatt-hour (kWh)