Systems of PhotoVoltaic Solar Generation
There are two systems of electric power generation from solar cells :
- Roof top array system
- Satellite system
1. Roof Top Array System :
- This system is mounted on roofs.
- It is an earth based solar system.
- In such system the problem of energy storage is difficult.
- But the solution this is:
(A) Electrochemical storage : Batteries must have capacity of getting charged and discharge for a length of time.
(B) Hydro-storage : When generated power is much more the water is pumped up-hilled and at the time of peak demand water is allowed to flow to drive generators.
(C) Mechanical storage : In this speed wheels.
(D) To store energy In the form of Hydrogen, which can be re-converted into electricity in fuel cells. Hydrogen is obtained by electrolysis of water by the output of the solar cell. EA (A)
2. Satellite System :
- It is tried by Advance of countries. To build space power station in synchronous orbit around earth. But this system microwave beam can be produced. The power will be transmitted to antenna on earth and converted back Into electric power. Till now trials in this directions are going on.
3. Solar Photovoltaic (PU) System (i.e. Power plant) is shown by states (blocks) and working :
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| Figure A |
4. Components in PV System Solar Generation and their functions:
For Figure, please refer to Figure A
Components :
1. Photo voltaic array
2. Inverter
3. Energy storage
4. Load centre (Distribution)
1. Photo voltaic Array :
- Solar cell is the basic component of PV solar generation system.
- When exposed to sunlight, PV cell generates electricity. One fuel cell generates electric power of 3 watts. Its voltage is 0.5 volts and current up to 6 Amp. (V x I- W; 0.5 x 6- 3 watts).
- Such so many cells are arranged together to form a module.
- Modules together form a pannel and so many pannels constitute an “Array”.
(i) P.V. Array :
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| Figure B |
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| Figure C |
- This is a power processing unit.
- It changes voltage levels and waveforms.
- Inverter converts DC Into AC.
- In the Inverter unit, some protective units are connected such as :
3. Battery :
(i) Lead acid battery
Charge Controllers :
- These units are battery control units. The main function of such a controller is to ensure proper charging and discharging of batteries within the prescribed limits.
- If battery is over charged there is a loss of electrolyte, corrosion and plate growth. This is controlled by the controller and the battery is safeguarded from overloading.
- The controller helps scientific charging of the battery L.e. at the beginning at high current and then gradually current is reduced as the charging process is on completion.
4. Protection and smooth utilization of electrical energy so produced as an output :
- Keeping the system in proper working condition, utilization of energy, maximizing the output and protection of components, protective devices are provided in the system.
- Voltage regulators’ are necessary in the system. Voltage output from PV panels varies as light intensity from sun varies. This results in fluctuation of load current. These regulators ensure voltage fluctuation within permissible limits.
Blocking Diodes :
- These diodes are used to prevent the back flow of current towards array.
- The day period, with bright sun-shinning the electricity is produced by PV cells, battery gets charged. But in late hours and night period when there is no sunlight, current will try to flow in the reverse direction from battery to arrays.
- This may result in damaging the arrays.
- Blocking diodes prevent such backflow and protect the system.
Circuit arrangement for supplying power to D.C. load or A.C. load :
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| Figure D |