The Difference Between Off-Grid and On-Grid Solar Systems
In recent years, solar power has become increasingly popular for homeowners and businesses looking to reduce their carbon footprint, save on energy costs, and increase their energy independence.
When it comes to making solar power system installation decisions, there are two types of systems: on-grid and off-grid. And because you're investing in expensive equipment that will last for many years, you have to make the right choice.
Choosing between a grid-tied (on-grid) or off-grid solar system depends on various factors such as location, power requirements, In this article, we will explain in detail the differences between off-grid and on-grid solar systems.
What is the Difference Between Grid Energy and Solar Energy?
The "grid" is mainly composed of high-voltage transmission lines that transmit electricity over long distances, as well as low-voltage distribution lines that provide electricity to individual customers.
The majority of the electricity that powers a typical grid system in many regions around the world is still produced from traditional energy sources such as coal, natural gas, and oil. Fossil fuel power plants emit large amounts of greenhouse gases.
On the other hand, solar energy systems are used to convert the sun's energy into electricity using solar panels that consist of solar cells. These cells convert direct sunlight into electric current through the photoelectric effect.
Since the source of power in a solar power system is sunlight, it is considered a renewable and sustainable energy source. Unlike fossil fuel power plants, which produce large amounts of greenhouse gases, solar power systems do not generate any greenhouse gas emissions.
Major Difference Between On-grid & Off-grid Solar Systems
Off-grid solar systems are designed to operate independently of the main utility power lines. An off-grid system requires batteries to store excess electricity generated by the solar panels, and often requires backup generators for times when the solar panels are not generating enough electricity.
While on-grid solar systems are connected to the utility grid, These systems operate in parallel with the grid and do not require batteries or backup generators because they can rely on the grid for power when the solar panels are not generating enough electricity.
Since the grid tied system is connected to the main power grid and can export excess electricity to the grid, there will be fewer components compared to an off grid solar system.If you want a cheaper solar power system, an on-grid system is the best option for you. However, if you are in an area where grid power is unstable or not available at all, off grid solar systems are definitely the best option for you.
Off-Grid Solar System
An off-grid system is an electrical system that operates independently of the utility grid. It typically consists of solar panels, a battery bank, and an inverter. The battery bank is used to store excess solar energy generated during the day, which can then be used at night or during periods of low solar output.
Off-grid solar systems operate independently of the utility grid and do not rely on the grid for frequency and voltage set points. Instead, off-grid systems use battery inverters that are designed to create and regulate their own AC voltage and frequency.
In addition to the AC supply, off-grid solar systems can provide a DC supply. The 12V, 24V, or 48V DC supply can be used to power DC appliances directly without the need for an AC inverter. This can be especially useful for appliances that are designed to run on DC power, such as LED lights, fans, pumps, and other low-voltage devices.
By using DC appliances, the system can be more efficient since there is no need to convert the DC power to AC before using it.
Off-Grid Solar System Applications
The systems are an excellent solution for areas where grid power is inaccessible or unreliable, as they can provide a reliable source of electricity without the need for a connection to the electrical grid. Here are some common places where off-grid solar systems are installed:
- Remote areas.
- Islands.
- Developing countries.
- Emergency situations.
- Army camps.
- Recreational vehicles.
- Communications towers...
On-Grid Solar System
A grid-tied solar power system is simpler and less costly because it includes fewer major components (solar panels and inverter).
The system uses an on-grid solar inverter, requires a grid
connection to function. To ensure that the inverter works and syncs
properly with the main power grid, it needs a reference voltage and
frequency from the grid. This is done by sampling the voltage and
frequency set points of the main grid before switching on and
converting DC electricity into AC.
By synchronizing with the grid, the inverter can ensure that the
electricity it generates is in line with the electricity provided by
the main grid, which is crucial to maintaining a stable and reliable
power supply.
The system uses an on-grid solar inverter, requires a grid connection to function. To ensure that the inverter works and syncs properly with the main power grid, it needs a reference voltage and frequency from the grid. This is done by sampling the voltage and frequency set points of the main grid before switching on and converting DC electricity into AC.
By synchronizing with the grid, the inverter can ensure that the electricity it generates is in line with the electricity provided by the main grid, which is crucial to maintaining a stable and reliable power supply.
Authority Approvals and Documentation
You can't build your own on-grid solar system and connect it directly to the grid; when you install a grid-tied solar system, it will be connected to the main power grid and therefore must be subject to regulations and standards set by the utility company. That's because the electricity your solar system generates is fed back into the main grid, which is shared by neighboring homes, transformers, transmission lines, distribution lines, substations, and other utility grid components.
Before installing your on-grid solar system, there are some permits, approvals, and documents that you need to submit to the relevant authorities. Here are some common things you may need to submit:
- Approved NOC (No Objection Certificate)
- TCL schedule (Total Connected Load)
- SLD (Single Line Diagram) with the solar system
- Solar Power System Layout...
Anti-Islanding Protection
If there is a power outage or blackout, the solar panels will not be able to generate electricity, even if the sun is shining. This is because the inverter will shut off to prevent backfeeding into the grid and potentially injuring utility workers who are trying to repair the power lines.
This is what they call "anti-island" protection, an important safety feature that is included in most grid-tied inverters.
This inverter feature isolates the solar power system from the grid during power outages to ensure the safety and reliability of the electrical system as a whole.
How are Energy Meters Connected to an On-grid Solar System?
Depending on the regulations and requirements for installing solar energy systems from your local power utility, the utility company may require the installation of two separate energy meters.
One is installed between the point of connection (POC) and the AC combiner box in a solar system. This meter is commonly referred to as a production meter or a solar meter. Its purpose is to record the amount of energy produced by the solar panels and fed into the grid or consumed by the home or building where the solar system is installed.
In addition to the production meter, a bidirectional meter is installed at the main connection point of the building, and it records both the energy that is imported from the grid and the energy that is exported back to the grid from the solar panels.
If your local utility implemented a net metering bill mechanism. You will receive a credit for the excess power produced by the solar panels.
Zero-export Controller and Power Limitation
Some utilities do not allow the export of power from solar systems to the grid, and in such cases, solar homeowners need to implement a zero-export mechanism on their system.
The zero-export mechanism is typically achieved by adding a device such as a load controller or a smart inverter that limits solar energy export to the grid. The load controller or smart inverter ensures that the amount of solar energy produced by the system is limited to the amount that is being consumed by the home at any given time, thereby preventing any excess energy from being fed back into the grid.
Solar panels will not produce electricity unless there is a load; the inverter curtails the production of solar power to match the load requirements of the home or building. This means that the inverter will only allow the solar panels to produce as much energy as is required by the appliances and other electrical loads at any given time.
Solar Power System Components
| Off-grid Solar System | On-grid Solar System |
|---|---|
| Solar Panels | Solar Panels |
| Off-grid Solar Inverter | On-grid Solar Inverter |
| DC Combiner Box | Meters |
| Solar Charge Controllers |
DC Combiner Box |
| Batteries | Protection Device |
| AC Breakers |
AC Combiner Box |
| Generators (Optional) | Meters |
| Solar Charge Controllers |
Point of Connection AC Breaker |
The top 5 Differences Between Off-Grid and On-Grid Solar Systems
Mohamed Bellamine
I'm the blogger behind Goo SolarPower. As a solar engineer, and a strong supporter of renewable energy. I've always been interested in Solar devices. I loves to write articles, guides, and tutorials about solar PV technology. Through goosolarpower.com I want to help people build and understand how solar power systems work.