What Is On-Grid Solar Rooftop System?

On-grid means your solar system is tied to your local utility's GRID. This is what most residential homes will use because you are covered if your solar system under or overproduces in regard to your varying energy needs. All this means for you is that your utility system acts as your battery space.

How On-Grid Solar Rooftop System works?

1. Firstly, when photons from the sunlight hit the solar panel, then solar cells with the help of photovoltaic effect(PV) transform it into direct current(DC).
2. Direct current (DC) is then transmitted through cables to DCDB (direct current distribution box)which is a piece of safety equipment for DC, and then it flows to an inverter. (An inverter converts DC to AC with defined frequency and voltage.)
3. From the Inverter, the alternating current(AC) goes to the AC Distribution box (ACDB)which is safety equipment for the AC part.
4. From ACDB it runs to the Bi-directional meter and then to the Local Grid.
5. Whole system structure, Panels, Inverter are then grounded.
6. One Lightning arrestor is used to guard the solar structure and panels against lightning.

Flow Of Solar System‍

Solar Panels

• A solar panel consists of multiple solar cells which are primarily made up of silicon semiconductor material. Sunlight consists of various photon particles, so when sunlight strikes the solar panel, it converts light energy into the Direct current (DC).
• The solar cell is a device that converts photons from sunlight into voltage and current. This phenomenon is called a Photovoltaic effect, and thus a solar cell is also called a PV (Photovoltaic) cell.

Inverter

• It is the heart of the whole solar power plant and the essential component of being understood. The Inverter converts the direct current coming from solar panels through DCDB into the Alternating current and sends it to the Grid via ACDB.
• One major thing it does is to sustain the frequency and Voltage of AC current to the accurate frequency of the Grid. In India, which is 50 Hz and 230 Volts.
• Choosing a proper Solar panel and Inverter are two main parameters customers should take into consideration before purchasing a solar system.

DCDB (Direct current distribution box)

A direct current distribution box is the device that controls DC power that flows from within the solar panels.

But why is it needed?

DCDB holds the necessary devices that protect solar panels and solar inverters from any damage.

• It incorporates circuit breakers that command to switch off the device when the fault has been observed.
• Sometimes, surges also occur, which are the brief overvoltage spikes or disturbances in an electrical power system, holding the capacity to damage or
  

destroy any electrical equipment. And so, DCDB contains surge protection, which is the great advantage of this device.

ACDB (Alternating current distribution box)

• This is a safety circuit that is a combination of SPD (Surge protective device) and MCB (Miniature circuit breaker).
• It protects the solar Inverter as well as the load from any surge (sudden increase) in voltage and other faults in the load circuit. It is connected between the Inverter and Load/Ground.

Bidirectional meter

• When the solar system is On-grid type, you will see that there will be a separate meter to distinguish the energy production from solar energy consumption of your load (equipment). So by reading the numbers of this meter, you can calculate the net energy used by you, which can be negative and positive.
• The NEGATIVE - Your solar power plant has produced more energy than your overall household energy consumption.
• THE POSITIVE - You have taken that amount of excess electricity from the Grid (local electricity vendor), for that only you have to pay to DISCOM (Electricity distribution company).

Grounding/Earthing

• This is a very crucial part of any electrical system because it is a safety guard for all your operations as well as the person himself. Earthing means connecting all the equipment with the earth's conductive surface for safety purposes. Earthing of all the installation parts is extremely important.

Type of Earthing in Solar On-Grid System

There are three types of earthing in an On-grid solar system:

1. AC earthing:
   

AC earthing includes the Inverter output, ACDB, and household load all are connected with the earth's surface, so if any fault occurs in the AC part of the system, all the equipment will be safe.

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2. DC earthing:

DC earthing includes the Solar Panel, Structure of the whole solar system, DCDB, and Inverter input. These all are connected to the earth's surface, so that if any fault occurs in the DC part of the system, then all equipment remains safe.

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3. Lightning arrestor (LA) earthing:

A lightning arrestor is a device that is installed on the solar structure to protect the solar panels, wires, and structures from the hazardous effect of lightning. This LA cable is also connected directly to the earth's surface without any other parts connected.

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Solar structure

The solar structure is usually divided into three parts: Legs, Rafter and Perlin. The inclination angle of the structure depends on the Latitude angle of that particular area. In India, the structure is typically made with hot deep Galvanized Iron to ensure strength and stability.

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