Grid Code

Updated 2026-08-24 · Read this page as Markdown

The set of technical rules a distributed generator must comply with to connect to the public network, covering voltage and frequency operating limits, power quality, protection settings and required responses to grid disturbances. Inverters are certified against specific national grid codes.

Examples include EN 50549 and the German VDE-AR-N 4105 in Europe, and IEEE 1547 with UL 1741 in North America. Compliance is not a formality: the applicable code is selected in the inverter's commissioning menu, and choosing the wrong country profile can mean nuisance disconnections, an installation that fails inspection, or a refused connection agreement. Modern codes increasingly require grid-supporting behaviour — reactive power control, ride-through of brief voltage dips, and power reduction as frequency rises — rather than simply disconnecting at the first sign of trouble.

Related terms

Arc-Fault Detection (AFCI) A protective function that monitors the DC circuit for the electrical signature of an arc caused by a damaged conductor or a loose connection, and shuts the inverter down when it detects one. It is required on PV DC circuits above a defined voltage in several jurisdictions. Curtailment (export limiting) The deliberate reduction of an inverter's output below what the array could deliver, in order to respect an export limit set by the network operator. Zero export means the system is curtailed whenever generation exceeds on-site demand. Feed-In / Export The energy a PV system sends to the public grid when generation exceeds on-site demand. It is measured by a bidirectional meter and remunerated or netted according to the local regulatory scheme. Islanding and Anti-Islanding Protection Islanding is the dangerous condition in which a grid-tied inverter keeps energising a section of the network after the utility supply has failed. Anti-islanding protection is the mandatory function that detects this and disconnects the inverter within a fraction of a second. Rapid Shutdown A safety requirement that the DC conductors of a rooftop PV array be brought down to a low, touch-safe voltage quickly once an initiator is operated, so firefighters and maintenance staff can work on the roof. It is enforced by module-level or string-level shutdown devices. Residual Current Monitoring (RCD / RCMU) The detection of leakage current flowing to earth rather than returning through the intended conductor, which indicates an insulation fault and a possible shock hazard. Transformerless PV inverters include an internal residual current monitoring unit sensitive to both AC and DC leakage.

Grid Code

Related terms

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