Page 308 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

The main components is BOS assembly are:

• Storage battery
• Charge controller
• Inverter
• Support structure
• Junction boxes
• Wire, cables and fuses

• Connections and switches
The functions of the above components are explained briefly below:
Storage battery
The most small systems used for lightening needs only 12V battery for longer system like refrigerator, 24V is
used. If helps to keep the wire size small and system losses to a minimum. It needs to be handled carefully. If
must not be over charged or fully discharged to prevent from damage.
Charge controller

If the battery is not able to control charge on its own. This work is done by a simple automatic device known as a
charge controller in the following way.
• It senses the battery charge and switches ‘OFF’ the charging current and avoid from damage.

• It disconnects the appliances when the battery charge goes below a set limit.
• Prevents reverse current and protects from short circuit.
Inverter
A solar system produces only DC power. But home appliances need AC power. The device (example CFL) is
required for this purpose to convert DC into AC is called as inverter.
Support structure
The solar module cannot be simply placed either on ground or roof. It needs to collect the sunshine at an angle.
To keep the module safe from any strong winds support structure is used for solar PV system.
Junction boxes
It is meeting point for many wires. These may be from a raw of modules are from modules to a battery bank. A
junction box is made of an unbreakable material (ie) polycarbonate. It makes use of copper connectors for a high
current flow. It protects the system from moisture.
Wires and fuses
This solar systems carry a low voltage but high current. So, the large diameter wire is needed. Fuses keep the
solar equipment safe against the short circuit.
Mounting of charge controller
- Mount the controller to the wall into screws that fit to the wall material.

- Connect the battery cable assembly with fuse supplied along with the controller.
- Connect first controller and then battery and two modules
- Connect the wires to the load and only then to controller.
Electrical connection

• Connect the battery to the system only after getting fully charged.
• Do not switch ‘ON’ charged the loads for 2 - 3 days (when battery is ‘ON’ a full charged)
• Connect the array cable to charge controller with correct polarity.

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CITS : Power - Electrician & Wireman - Lesson 106-116