What is anti-islanding on a grid tie inverter?
The term “anti-islanding” refers to a feature of a grid tie inverter that senses when there is an power outage and shuts itself down and stops the production of electricity. There is a common misconception within solar panel and wind turbine consumers that if there was a blackout their grid tied system would keep them going through an outage, well this is not true because of grid tie inverter anti-islanding feature will stop the production of electricity when the gird goes down. You have to realize that when you own a grid tie system, the energy is stored in the grid, so the system is as reliable as the grid itself.
When the grid goes down, the anti-islanding feature on the grid tie inverter will realize that either there was a sudden change in system frequency, voltage, rate change of frequency, increase in kW beyond normal levels, or a change in kVAR and shut down the inverter. When the inverter shuts down your system is no longer producing electricity for the safety of the people who will be working on the grid to repair it. There are grid tie inverters that are still under development such as the TerraWatt Power inverter which works during an outage because the inverter redirect the power being generated by a system back into the property without shutting down and keeps the linemen safe because the TerraWatt Power inverter does not send electricity into the grid when it senses there is an outage.