There are mainly three types of solar systems available.
- On-Grid solar system
- In this system, generated output of the solar system will feed to the local grid
(Power supply line). The house doesn’t utilize this generated power.
- Off-Grid solar system
- In this system, we store the energy generated by our solar plant with the use of a
Battery, and that energy is then utilized to power our household types of
equipment.
- Hybrid solar system
- This is the combination of both On-grid and Off-Grid systems. The energy
generated by our plant is stored in a battery for backup support in case of grid
power failure. After the battery is fully charged, we transfer excess electricity to
the grid.
India has achieved close to 100% electrification in almost all its rural and urban
areas. Many of the private sector companies like TATA, Reliance, Torrent, and
others have also partnered with state governments to provide electricity and have
done great work.
One of the major problems that occur in rural areas is transmission and
distribution losses. Due to these high losses, there are many power cuts and
shortage of power occurs in rural areas. To solve this problem, the Government of
India has set a target of installing 100 GW of solar power plants by 2022.
What is it there for me?
● Detailed understanding of each system
● Advantage and Disadvantages of each
First, let us understand the most common on- grid system
What is On-Grid Solar system?
On-grid, as the name suggests, is connected with the local grid (Power supply
line). In India, almost all the rural, as well as remote locations, have grid
connections according to the data. Also, India is a country where sunlight source is
in abundance. So, On-grid systems are the most common solar system used in
India.
How does it work?
In this system, solar panels convert the sunlight into direct current. This DC
current through the cables and then Inverter convert into AC (alternating current).
This AC current is directly fed into the local grid and the amounts of units are
measured through a meter. Our home appliances will continuously work on the
electricity supplied by the local grid company, so we won’t face any interruption in
power supply.
Let us understand this from this flow diagram:
Advantages
- It is the cheapest system among all.
- There is no use for batteries, so there is no fire hazard in this system.
- As govt. is giving many benefits for installing this solar power system, it is an
extremely cost-effective system.
What is an Off-Grid Solar system?
As the name suggests, Off-Grid means the system which is not connected to the
local grid (Power supply lines). In India, there are many remote locations and
villages where Electricity is not sufficient due to the high transmission and
distribution losses in electrical cables. At those remote locations, an Off-grid
system is the best solution.
So, how does it work?
In simple words, the electricity generated by the solar panels is stored in a battery
bank (multiple batteries) in the form of a DC current. According to the use of
household equipment, this DC current goes to the Inverter and is converted into
an alternating current, which is essential for our home equipment. From the
Inverter, it is then connected to the main power line of the house, and we can run
our appliances. This is the simplest work of the system, but actually, it is not as
simple as it looks!!
Let’s get some more deep insight into the system:
First, let us see how the electricity flows in the Off-grid system…
Now, to understand this system, we divide it into two parts.
- When it’s a sunny day and panels are producing electricity.
Sunlight having photon particles in it strikes the solar panels. Solar cell with the
photovoltaic effect converts these photons into direct current and voltage.
DC current flows through the cable to the charge controller. From that, it flows
to the Inverter where it gets converted into an alternating current, on which all
the appliances work.
From the Inverter, Ac current flows to the main distribution box of the home and
provides electricity. But the question is, what if we don’t want to run any
application at that moment? Then where will this current flow?
When there is an excess amount of power produced by the panels than needed,
this power will flow to the battery bank for future use. The charge controller is
thus an important device that controls the flow of charging and prevents batteries
from overcharging.
DC disconnect switch is also a safety measure device that lets the current flow in
a single direction from the charge controller to the battery bank, not the opposite.
- In the night or rainy days when panels are either not working or partially
producing output.
We saw that in the daytime when panels are generating electricity, the battery
bank is charged for the future.
DC current from the battery bank goes to the inverter, which converts it into AC
current. This current then goes to the appliance of home, and we can lighten up
our home.
DC disconnect switch ensures that currently doesn’t flow towards the charge
controller in this process.
People generally have to purchase one diesel generator as well because battery
backup can work mostly for 3-4 days only. So for remote locations in the rainy
season, a diesel generator is a cost-effective option rather than extra batteries to
use.
Advantages and Disadvantages
- In remote locations, this system is best because it is cheaper compared to
installing new grids. But in India, usually, all the villages and remote locations are
almost connected to the grid. So for home electrification, this system is rarely
used. - It is a very expensive system because we have to use multiple batteries for the
storage of electricity. Batteries have 5-7 years of lifeline and these are very costly.
So they need to be replaced after 5 years. - Due to the use of the battery, there is always a risk of fire or any other hazard in
this system.
What is a Hybrid Solar system?
Hybrid, as the name suggests, is a mixture of both On-grid and Off-grid systems. In
India, there are many remote locations and villages where the grid is connected
but power cut-offs are very frequent. So at these locations, this Hybrid system is
the best suitable.
There are two major things that we will study about the system:
- We will use the electricity from the grid when there is a stable supply. In case of
a cut-off, we will use the electricity stored in a battery bank to run our appliances. - The electricity generated by our panels will first charge our battery banks via
the charge controller, and excess electricity will go to the local grid. There will be a
separate meter that will measure the number of units we have supplied to the
local grid.
So let’s understand this system more properly by this flow diagram: Modern
technology advancement has taken one step ahead in this technology of
purchasing power from local DISCOM when it’s off-peak time. But we won’t get
into it.
Advantages and Disadvantages:
- This system ensures the highest chance of continuous electricity supply than any
other system. - It is less expensive compared to the Off-grid system because we can use fewer
batteries for the backup. - It is more expensive than an On-grid system because it uses a battery bank for
backup purposes in case of power cut-off. - Due to the use of the Battery, there is a risk of battery overcharge and
occurrence of a hazard.
