Grid-Tie PV System VS Off-Grid PV System

There are basically three types of solar PV systems existing today for solar power generation at home, including grid-tie, off-grid and hybrid PV systems. However, as expense and efficiency are concerned, grid-tie and off-grid systems are more popular and most installed around the world. Now let’s compare them with each other and help you decide which system should be suitable for your house.

grid-tie solar PV system
grid-tie solar PV system

Grid-Tie System

1. This installation requires your system is connected to the local national (utility) grid.
2. After the connection, the system can feed the electricity (usually extra electricity) it generates to the national grid (this helps it earns money from the grid), and your home can get the electricity from the national grid once your system stops generating electricity at night or in special conditions.
3. The current form your solar panels generates is direct current (DC), which must be converted into alternating current (AC) for home use by going through a PV inverter. The current converted by the inverter must be compatible with the voltage of the local grid.
4. The inverter also needs to be a grid-tie type. An off-grid one cannot be used here.

Off-Grid System

off-grid PV system
off-grid PV system

1. Off-grid means the system is disconnected from the local national grid and cannot feed extra electricity to earn money.
2. This installation needs storage batteries, which usually cost a lot of budget.
3. This system is suitable for installation in areas where houses cannot be connected to the national grid or where residents are far away from grids and cities.
4. It needs a charge controller which is used to charge the batteries of the system.
5. The DC from solar panels usually goes to a battery and then to an inverter.
6. This inverter is an off-grid inverter.

Grid-Tie Advantages

1. It can constantly power your house unless the national grid is down and the system meets its special conditions.
2. It can help earn money from the local government by selling extra electricity.
3. It costs less compared with an off-grid system because it doesn’t need expensive batteries.
4. It works more efficiently because its DC doesn’t to go into a battery. This process causes energy loss.

Off-Grid Advantages

1. It can be used in remote areas where national grids cannot reach.
2. It can store extra energy and use it whenever your house needs.
3. It doesn’t need the grid-connecting process.
4. It is totally environmentally friendly.

Current Condition

In comparison, residents around the world prefer a grid-tie system more, and many countries like the UK, the US, the Netherlands and China are encouraging their residents to install this system. But In India, an off-grid system seems to enjoy more welcome because many regions in the country cannot reach national grids.


The PV power system and its working principle

omnik solar power system
omnik solar power system

What is a PV power system?
It is a system which consists of solar panels, power-charging and -discharging controllers, a solar inverter, a tester, and other computer and mobile electronic devices, storage batteries, and other assistant power geenration devices. It works to generate electricity by absorbing sunlight and converts it into home use electricity.

What are advantages of the system?
1.It doesn’t have moving components that often produce lots of noise. It is home-friendly.
2.It is environment-friendly and will never emit polluted air or water.
3.It doesn’t need a procedure which needs biofuels to power itself.
4.It is easy to repair and maintain, and so you don’t have to spend so much money on its repair and maintenance.
5.It is reliable and stable.
6.The solar panels all have a long lifespan and they often span up to 25 years.
7. You can easily expand your scale of power generation according to your individual demands.

Use of the PV power system
It is now a widely used system that can be generally divided into two types: stand alone and grid-tie power generation systems. So far, developed countries such as the UK and the US have begun to install the grid-tie power system in their cities. China and Japan are now following this fashion too. They are mainly building residential rooftop PV power systems and MW-level large-scale grid-tie power generation systems. It can be used in different areas, such as home, transport, communications, space and others.

Working principle
Although they have different sizes and forms, their working principle is the same. Generally speaking, it is a system that generates electricity from sunlight by its solar panels, and then charges the storage batteries through the control of the controller, or supplies the direct current load if the load requirement is satisfied. If there is no rich sunlight or if it is at night, controlled by a controller, electricity will be transmitted to the direct current load. If the electricity needs to be used in a house, the direct current must be converted by a solar inverter into alternating current.

Why Go Solar?

Solar Panel Home
Solar Panel Home

Why do we need to turn to solar energy for generating electricity? Indeed, there are various reasons to discuss. In this article I will show you some of the most important reasons why we should go solar today.

Free resource
Solar electricity comes from sunlight, which has worked for over 1 billion years and is still young and energetic. It can provide us with a rich resource. More importantly, sunlight is clean, and the solar PV system which converts it into electricity doesn’t produce waste during the process as other power generation forms do.

Money saving
Money saving can be divided into two sections: reducing family cost and social burden. For a family, installing such a power plant needs money as invest. In the beginning it is a little bit much, while this invest will help you save the money that you usually pay for the utility grid. On the other hand, as public electricity price rises, your family will have to pay the electricity bill more than ever before. This might not be a great deal for rich family, while it must be a nuisance.

Less noise
Factories often have noise when their machines begin to work. For a solar power plant, it doesn’t have to produce any noise because its machines are those solar panels which stand quiet all the time in the sun. For a residential PV system, the owner doesn’t even need to think about it. Solar panels are on the rooftop and where does the noise come from? The only noise should come from the solor pv inverter is just the very low sound when the inverter works.

Beneficial for remote areas
Many families are still located in remote areas where utility grid cannot reach or is too expensive to reach. For this concern, solar power plants can help do this business. Or if you are not willing to share solar electricity with other families in these areas and have a certain financial support, you may choose the independent residential power generation system.

Tech improvement prospect
Solar electricity is powered by high technology. Today’s highest sunlight conversion rate can reach up to 40%. As technology improves, higher conversion rate can be expected and more sunlight electricity is possible too. In this case more electricity can be harvested and less money will be spent on it.

Easy to install at home
As solar power technology improves, homes can generate electricity themselves too. To install this tiny power station at home is not a complicated business. Install a few solar panels on the rooftop, use some wires to connect, install a storage device (only for the independent PV system), install a PV inverter inside your house or outside it. Everything is done unless you need another meter to record your electricity generation amount. Some companies even provide software and apps to monitor the whole system, and so you can use you smart mobile phone to do the monitoring job. It is suggested that you install the PV inverter inside your garage, utility or loft (if your family has one).

Environment friendly
Our air quality now is not as standard as before, and the low quality will surely threaten our heath and can cause respiratory disease. Also, global warming is turning over the balance of the world’s climate, and the most serious culprit that causes it is greenhouse gasses which are produced by so many oil, gas and geothermal and other energy companies. So, it is necessary and urgent to protect our fragile environment by going solar. It is complete air pollution free.

Water saving
The world is facing water shortage, while many industries including gas, oil, coal and nuclear are still using so much water for cooling. This consumes large gallons of water. If more and more families can use solar electricity or build their own solar power systems, much more water for cooling will be saved for sure. This seems too big, while when you face water shortages, you will realize “how important water is for me.”

More jobs to be created
Many countries face serious unemployment including France, Spain and US. If more jobs can be created during this process, this will be a great achievement. But how? The fact is the solar energy industry is a labor intensive industry not like oil or other businesses (they are much more capital intensive). When more people go solar, more jobs will surely be created. This is its great trick!

However, apart from these advantages mentioned above, there are still other reasons for going solar. Meanwhile, we cannot ignore that solar energy can help generate electricity only in daytime, and it cannot generate as much electricity as it can in sunny days. Thus, when we choose it, we still need to consider specific conditions for specific areas and other related conditions. But going solar for us is a trend and will expand for sure.