Types of Solar Photovoltaic Systems

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Types of Solar Photovoltaic Systems

Depending on the method of utilization there can be two configurations :

  1. Stand alone system.
  2. Grid connected system (Interactive Systems)

1. Stand Alone System :

The characteristics of this system are :

  • They supply power to a system Independently without the use of any common grid or connection to any other system.
  • Operates autonomously and independently.
  • Commonly used for backup power where connecting to grids are very costly.
  • May or may not use energy.
  • Can be used to power DC loads, also the AC loads using an inverter.
  • Hybrid stand alone systems may include other power producing devices also for back up.

Figure A shows the block diagram of a standalone system

Stand Alone System
Figure A

Stand alone systems may be of any one of the categories given below :

  • Direct Coupled Stand alone
  • System Stand alone System with Battery
  • Storage Stand alone System with Batteries and Charge Control Stand alone
  • System with AC and DC loads
  • Hybrid Stand alone Systems

These systems are briefly described below :

1. Direct coupled stand alone system :

Figure B shows this in block diagram.

Direct Coupled Stand Alone System
Figure B

In this the solar array is directly connected to the DC load. There is no energy storage. So they can be used to operate devices required only during sunshine hours like water supply pumps for agricultural purposes.

2. Stand alone system with battery storage :

This is shown in Figure C. In this the PV array charges the battery and the battery supplies DC power to the loads. There is no charge control and is susceptible to overcharge and over discharge.

Stand Alone System with Battery Storage
Figure C

3. Stand alone system with batteries and charge control :

Figure D shows this type of system. This has got charge control for controlling the charge discharge.

Stand Alone System with Batteries and Charge Control
Figure D

4. Stand alone system with AC and DC loads :

This system can be used to power AC as well as DC loads. Hence it needs inverter also in the circuit. Figure E shows this system. In addition the main AC supply also may be used for charging only in case of emergency.

Stand Alone System with AC and DC Loads
Figure E

5. Hybrid standalone systems :

In a hybrid stand alone system one or more sources in addition to the PV panels me used. Sources like stand by engines, turbines fuel cells etc may be used in conjunction with PV arrays, Figure F shows this. Thus reliance on any single source is reduced. This also reduces battery storage capacity and size of PV arrays.

Hybrid Stand Alone System
Figure F

2. Grid Connected Systems :

In this system the power generated by the PV array is given to the grid or to the AC loads directly. When the power generation exceeds the requirement of the loads it is supplied to a commercial grid. Thus the system forms part of a large network. The output from the inverter has to satisfy the norms in terms of the quality of the electrical standard so that it can match with the grid system. Figure G shows a grid connected system.

Grid Connected System
Figure G

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