Solar Protection Relays are used in embedded generators over 30kW. There are two main categories of Solar Protection Relays, these being Grid Connect Relays and Zero Export Relays.
What is a Grid Protection Relay?
A grid protection relay, sometimes called a grid-tie or mains protection relay, is a device that ensures the power quality is acceptable to be exported to the grid. These include under/over voltage, under/over current and frequency protection. Whats makes these suitable for embedded generators is the anti-islanding function in addition to power quality protection.
What is Anti-Islanding?
Anti-Islanding is a type of electrical protection for embedded generators such as grid connected solar, wind or diesel. It ensures the generator disconnects electrical supply to the grid in the event of a blackout. Anti-Islanding protection exists to protect personnel and equipment connected the grid in the occurrence of a fault or maintenance.
What is a Zero-Export Relay?
A zero export relay is similar to a grid protection relay as it has all of the power quality and anti-islanding protection functions. It has the added function of being able to monitor the current flowing and disconnect at a pre-set value. This ensures the embedded generator never exceeds the maximum export value allowed by the DNSP.