The inverter of a photovoltaic production system continuously monitors various parameters, in particular the frequency and voltage at the inverter output terminals.
When any of these parameters exceeds the permitted limits, the inverter automatically disconnects from the electricity network until all parameters are acceptable again. This is also known as "decoupling" from the network.
This disconnection system is essential to guarantee personal safety and protect the installation.
Unfortunately, when the inverter is decoupled from the network, the photovoltaic system is no longer producing any electricity, which is neither good for the environment nor for the system's profitability.
What's the cause?
Most often, the disconnection is due to voltage surge: the voltage measured at the inverter's terminals exceeds the maximum permitted limit, set at 253 V on average over a 10-minute period.
For example, if a large number of solar panels have recently been installed in the same area, and they are all injecting electricity together, this can lead to a voltage surge on the network and a decoupling.
On the contrary, an undervoltage problem can arise, for example, if a large number of electric vehicles start charging simultaneously in the same area.
To avoid decoupling, it's essential not to oversize your installation and to autoconsume as much of the energy as possible yourself.
How do you resolve this problem?
Contrary to what you might think, in Brussels, decoupling is not usually linked to voltage surges on the distribution network.
In most cases, the origin of the problem lies in the installation of the photovoltaic system on the customer's premises. Decoupling is often linked to the following cases.
- Incorrect decoupling parameters: inverters set to stricter values than those permitted in Belgium (e.g.: instant decoupling as soon as voltage exceeds 253 V).
- Undersized cable: for example, the cable between the inverter and the electrical panel, especially when the cable is long.
- Incorrect load distribution: this is particularly the case for installations over 5 kVA, when several inverters are connected to the same phase.
Please consult the Synergrid FAQ to find out more about possible reasons for decoupling.
How do you identify the origin of the problem?
If you notice that your inverter is frequently disconnecting from the grid, you can contact us to analyse the situation.
Network monitoring
Sibelga constantly monitors the voltage on the electricity network to identify any areas that may be affected and anticipate any problems with voltage surges.
This way, we can easily confirm whether there are any known surge problems in a particular area.
- When network problems arise at network level, they can sometimes be quickly resolved by technical intervention.
- The resolution time will be longer if major infrastructure work and permits are required.
Checking your installation
If no problems are detected on the network, a voltage check at your meter should be carried out.
- If you have a smart meter, we can collect the voltage history remotely.
- If you don't have a smart meter, we can install a power quality meter to read the voltage.
No surge problems detected at the meter? Then the problem lies in your installation. In this case, we suggest you have it checked by a certified installer.