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.

Working

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.

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FLOW OF SOLAR ENERGY AT THE ROOFTOP

Sunlight Solar panel DCDB Inverter ACDB Bi-directional meter Grounding

Now you have an idea of what devices are used in the solar rooftop power system. But, aren't you eager to acquire some more information about the tools? So let's just begin.

WORK OF EACH DEVICE USED IN SOLAR ROOFTOP POWER 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.

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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.

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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.

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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.

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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 and 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).

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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.

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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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Solar energy covers the major part of renewable energy, and the list of advantages is never-ending. In today’s blog, we will be talking about a part of the solar world that is adding a good amount of advantages to the overall system, that is“ solar microgrid”.

The term solar microgrid can be broken into two parts solar and

microgrid for better understanding, let's dig deep into

what is microgrid?

The microgrid is basically a smaller version of what the utility power system is, just think about if the power goes away, and you want to have safe, reliable, and more efficient power than what? In this scenario, a microgrid comes into the picture. Most places already do have assets like solar, utility, generator, storage, etc. A microgrid combines all of those systems together with the brains to make it work efficiently, reliably, and safely.

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Now when we combine both solar and microgrid we get solar microgrid, let’s understand the whole term now.

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What is a solar microgrid?

A solar microgrid has the ability to operate independently of the central grid. Both solar energy and solar microgrids are great for the environment, as they both generate energy using solar power. When a microgrid is able to remove itself from the main grid is called “islanding”. Their ability to function in “island mode” using sensors, controllers and active management software ensures that the power supply is maintained independently of the main grid even in the event of disruptions. A microgrid can connect and disconnect from the grid to enable it to operate in both grid-connected or island-mode. This helps in preventing damage to the grid in case of any abnormality. Adding benefits during natural disasters such as wildfires or hurricanes, kind of high risk. if the stable utility grid is not available. off-grid solar system. The main goal of using the solar microgrid is to minimize the usage of non-renewable energy sources.

Now you know what is microgrid, let’s jump into the part of the system which helps the system to control everything.

Smart control system

In a microgrid, there is a system called a smart control system. This smart control system can also be called the brain of the solar microgrid. Its work is to systematically gather all useful information of the network system and automatically send commands to each part of the system. The outcome of this leads to a healthy, efficient, and reliable system. The microgrid will enable us to shift from central power generation to local flexible, reliable forms of sustainable power energy.

But where to use Microgrid? Keep reading to know more about its components, types, advantages, disadvantages.

The demand for microgrids is increasing in typically the remote areas where the access to power utility is not yet available continuously, places like remote villages, off-grid islands, industrial projects, places where disasters are prone to happen more, etc.

In recent times urban places are also showing more interest in microgrids, like power hospitals, university campuses, data centers, etc. it can be safely be said that the future held a good scope for microgrids in urban and rural areas.

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The next big question is “What are the components of microgrid”?

In terms of solar, all components are the same as the solar system, but the additions are as follows.

• Distributed Generating Units.
• Load Centers.
• Distribution network.
• Control Unit(s)
• Electric Power Storage

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Type of microgrid system

Generally, the microgrid can be classified into two categories

off-grid and grid-connected Off-grid

Off-grid microgrids are not directly connected to a grid and are of great help in the area where there is no access to a wide-area electrical grid but the significant need for electricity. Mostly off-grid microgrid is use

in island and remote areas On-gird

On-grid microgrids are directly connected to a grid. Urban people do this to avoid power outages, increasing reliability, Hospitals, airports, university campuses and large industrial plants all utilize microgrid components to effectively integrate backup power generation into their electrical system.

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Advantages

• Reduces the electricity bills.
• Carbon footprints will be reduced using solar microgrids.
• The usage of generators is reduced and the level of CO2 emissions is also lowered down which helps in environmentally sustainable.
• The system improves and becomes more efficient.
  
• It can function independently of the utility system in case there is a power outage in the area.
• It reduces the energy demand from the existing utility grid
• Solar Microgrid allows the storage of excess solar energy to battery banks. The energy stored can then be used during the night or even on cloudy days.

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Disadvantages

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• A solar microgrid requires regular maintenance of solar inverters and battery systems.
• It requires monitoring of the frequency and voltage levels of the whole system to be able to function effectively.
• The cost of battery systems is currently quite high.
• Protection of the system is hard
• The complexity of the entire solar microgrid increases the more you add another type of load or energy source.

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When you think about electricity, you think about gird, but today in this blog we will be talking about a system that provides electricity without the involvement of gird. How? Simply with an off-grid solar system.

In this blog will aim to provide you with all necessary information about an off-grid system so that you can avail a booster of knowledge in simple terms. The basic question that haunts many is what is an

off-grid system and without a grid how can we have access to electricity? So let me start off by telling you what is an off-grid solar system?

An off-grid system is also known as a standalone PV system, where electricity is harnessed by solar panels and then stored inside a battery. This process is not connected to any grid and provides an independent power supply to your home/office, anywhere where you can use electricity.

Thinking about where to use an off-grid system?

Well, the most commonly used areas are where there is no grid available like remote faraway places, places with frequency power cut issues, remote/rural locations where access to the grid is difficult and costly.

Using electricity without grid-connected is confusing? Okay, so now let's talk about it’s working to give you a better picture.

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Working of an off-grid solar system.

As the system is not connected to the grid, the battery plays an important role in energy storage. The process goes as When the solar radiation fall on the solar panel it generates energy in the form of direct current (DC) which then goes to the charge controller that regulates the flow of charge and supplies the regulated power to the battery. In an off-grid system, battery is a showman that stores all the energy to supply power during the night or on non-sunny days. Like on

a sunny day when the solar panel is operating on full efficiently and produces enough power to feed the load and also to charge the battery, this charged battery is then used to power the load in the night or where the grid is not connected. The energy stored in the battery is in the direct current (DC) from, so this (DC) is converted into alternating current (ac) with the help of an inverter. This converted AC energy is supplied to the loads connected to power the load with energy. And dim, your place is all light up!

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On the basis of its energy form, There are typically five types of off-grid solar systems, which you can choose according to the useage of power.

1. DC ONLY SYSTEM

This system is perfect to use on dc-powered appliances having 12 voltages or lower and is mainly designed to power low energy consuming devices. Here there is no solar inverter as DC power is directly fed to the appliances and no backup generator.

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2. AC only system

This system is designed to handle bigger loads and is equipped with a solar array. Here there is an inverter that converts the DC power into ac power that can be used to run your all household appliances. The backup generator is absent, so do ensure that your system can handle your loads in case of power outages and emergencies.

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3. Mixed DC and AC system.

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This is designed for powering light or low energy equipment, kind of similar to DC only system but have the addition of an ac inverter with no backup generator

4. AC system with backup generator

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Same as ac system but with back up generator. Generator is adding advantage for proving continuous power even during emergencies or power outages.

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5. AC system with wind and solar

This system run on both source of energy, solar and wind energies. During sunny days it works on solar and if there is cloudy and windy outside, wind energy is collected via wind turbine.

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The basic components of an off-grid system

1. Solar panels- (link)
2. Charge Controller

This component is necessary to regulate the current going to the batteries from the solar panels. They maintain batteries at a high state of charge without overcharging them.

3. Battery bank

This is used to store the excess solar power that’s generated beyond the needs of your appliances.

4. Generator (optional)

This is for backup purposes, just in case your batteries malfunction or there’s an overcast and your batteries are drained.

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5. Solar Inverter (AC)
   

Converting the DC power into AC power

A solar inverter is perhaps the most important component in the off-grid system. There are 3 types of inverters available in the market to choose from depending on the output waveform. What to choose is your next big question? Then read further to know the answer

1. Modified sine wave inverter

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This inverter is less expensive and has a time interval between the maximum positive and maximum negative points also called as a modified square wave inverter. You can not use this in an inductive load as it causes excessive heating that can affect the durability of the appliances. On the beneficial side of it, low-cost one can use it for

small devices.

2. Pure sine wave inverter
   

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Pure sine wave comes with a stable sin wave output and is also called a true value inverter. It is a good choice for sensitive electronic appliances. Further, it is classified on the basis of its frequency.

Low frequency; These inverters generate a high starting current, so it is more beneficial for compressors and air-conditioners that can be used for long run time.

High frequency: These inverters are free from electromagnetic effects and offer a higher power conversion rate with an ability to run both inductive as well as a resistive load. They are reliable and efficient with minimum losses.

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3. Square wave inverter;

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these inverters are not currently in use due to their instability and harmonic distortion. They generate poor quality unstable square wave ac output that can affect the durability of the inverter and also

So out of the mentioned 3 inverters, two inverters that you can buy is pure and modified sine wave inverter. The below table will help you to make your firm choice as to what to get.

Now you know what to choose and why.

The last thing to get into is the allover advantages and disadvantages of the system

Advantages:

• It is independent of a grid
• Easy to install in any remote area
• Output voltage can be regulated
• No need of synchronisation of frequency and voltage between grid and inverter

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Disadvantages

• Limited backup hours
• Complex to installed

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