On-grid solar power systems enable us to enjoy electricity and supply excess electricity to the grid. This sounds simple and easy, but there can be complications like solar islanding that can cause severe problems.
On-grid solar power systems are connected both to our homes and the grid. All the energy that solar power system generates is supplied to our home, and our energy requirements are met. If there is any excess energy, it is supplied to the grid.
Even though this excessive energy is utilized by the grid, and it also helps in fulfilling energy requirements at the grid level but it is not always safe.
What is Solar Islanding?
Due to technical problems or routine maintenance, the grid power is often shut down. The grid power shutdown enables the workers to work on wires without worrying about any possibility of getting electric shocks.
Even though the grid power is shut down and the wires are no more live, the on-grid solar power systems are still connected to the grid through the same wires.
In this situation, if the solar power system generates power and there is excess energy, it feeds the excessive energy to the grid. This causes the wires to carry a charge, and the wires go live again.
Now, the workers working on the same lines but do not know and get a shock which could lead to severe hazards. Moreover, the wires connected to any faulty equipment at the grid can also cause severe damage.
What is Solar Anti-islanding?
This process of solar power systems lighting up the grid during power shutdown is called solar islanding. And it is a potential problem for on-grid consumers and the grid. But it has a solution called solar anti-islanding.
Solar anti-islanding enables the safe operation of solar power systems during the shutdown of the grid supply. It keeps powering the home without feeding any energy to the grid. Since no energy is supplied to the grid, there is no chance of hazards.
How is Solar Islanding Detected?
There are 2 methods of detecting solar islanding.
Passive islanding Detection
The most common method is detecting the voltage and frequency. As soon as the grid supply turns off, the solar inverter cuts off the connection between the home and the grid.
Then the solar inverter starts powering the home directly from the panels or the battery storage. The disconnection between the home and the grid enables safe operations at both ends.
Active Islanding Detection
Active islanding involves sending and receiving a single between the grid and the solar power system. This keeps the solar power system informed of the status of the power supply on the grid.
As soon as a shutdown signal is detected from the grid’s end, the solar power system immediately cuts off the connection from the grid.
Why is Solar Islanding Detection Essential?
Solar islanding detection’s primary purpose is to avoid unwanted electric power supply to the grid, but there is more to it. Let’s discuss all the reasons in detail.
As long as there is the possibility of solar power systems charging the grid lines, the workers working on lines are prone to electric hazards. Since the grid can control the supply only from the grid’s end, it cannot avoid possible hazards from the on-grid solar power consumers’ end. The only way this safety can be ensured is at the consumers’ end and that too if solar islanding is detected and avoided.
Electric and electronic equipment are vulnerable to hazards if powered up during a malfunction. According to protocols, the grid supply is always powered off during repair if any faulty equipment needs routine maintenance. However, if the equipment is still powered up, it may malfunction, be permanently damaged, or even cause a hazard.
For these reasons, it is essential to ensure the grid equipment is not supplied power from the consumer’s end through a solar power system.
Since solar islanding detection involves monitoring voltages and frequency, it also cuts off the solar power system from the grid if the grid voltages are unsuitable. For example, in case of a low-voltage surge, the grid supply can affect consumers’ appliances. It can also cause the solar inverter to catch fire.
Since the solar power system doesn’t need to be turned off while the grid supply is shut down, the system keeps generating energy. However, if there is no system to detect islanding and regulate connection to the grid, it is necessary to turn off solar power generation for safety reasons.
Compliance With Net-metering Policies
Solar islanding detection feature is necessary in most countries, especially the USA. Without it, consumers cannot install an on-grid solar power system.
Solar islanding might sound technical, but it is simply a feature that regulates the connection between the solar power system and the grid. It ensures the connection opens when the grid supply is powered off. This helps keep both systems safe and elevates reliability and performance.
For these reasons, most reliable solar inverter brands add an anti-islanding feature to their inverters.