Feed-In / Export

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

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.

Export terms vary enormously by country and change over time, so a design assumption about their value should be treated as the least durable number in a financial model. What is technically fixed is the connection agreement: the network operator authorises a maximum export power, which is often lower than the inverter's rating and is enforced by curtailment settings in the inverter or an external meter. Where export is poorly paid or capped, the design logic shifts towards self-consumption and storage rather than towards maximising annual generation.

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. Grid Code 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. 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.

Feed-In / Export

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