Grid export limits are the maximum amount of electrical power (kW/kVA) a site is allowed to export back to the grid under its grid connection agreement. They are set by the DNO/DSO to protect the local distribution network from issues such as voltage rise, thermal overload, and stability problems, especially in areas with high renewable penetration.
What Are Grid Export Limits?
Export limits define the maximum amount of surplus electricity that can flow from a customer site into the distribution network.
– Usually expressed as a maximum export power value (kW or kVA)
– Can be fixed (e.g., “export capped at 50 kW”) or time/condition-based
– May apply to the whole site at the point of connection (POC), not individual assets
– Often enforced using a customer limitation scheme or export controller
Why Grid Export Limits Matter
Export limits affect how PV, BESS, and bidirectional charging can be operated.
– Protect distribution feeders and transformers from overload
– Reduce risk of local voltage rise and nuisance protection trips
– Enable DNOs to allow more DER connections by controlling worst-case export
– Prevent non-compliance penalties or forced disconnection
– Shape financial outcomes for DER owners and flexibility participation
What Drives Export Limits
DNOs set export limits based on local network constraints such as:
– Substation and transformer headroom
– Feeder thermal limits and protection settings
– Voltage rise risk during low-load, high-generation periods
– Fault level and power quality considerations
– Congestion conditions and planned reinforcement timelines
Export Limits in EV Charging Sites
EV charging sites may face export limits when they include on-site generation or storage.
– Solar canopies at charging hubs can create export peaks during midday
– BESS may be restricted from exporting unless within limits
– V2G export may require specific approvals and strict control
– Export limits are often paired with dynamic export limitation and EMS control to prioritize self-consumption
How Export Limits Are Managed
Typical methods used to comply with export limits include:
– PV curtailment when export approaches the cap
– Charging BESS to absorb surplus renewable energy
– Increasing flexible demand such as EV charging to raise self-consumption
– Using an export limitation controller measuring at the POC
– Configuring fail-safe behavior so export defaults to a safe state during comms loss
Common Pitfalls
– Measuring at the wrong point, causing export exceedances at the utility meter
– Assuming “zero export” is easy without proper control and response time
– Control conflicts between PV inverter settings, EMS, and BESS controller
– Not providing commissioning evidence to prove export control works
– Ignoring that export can occur during unexpected low-load periods
Related Glossary Terms
Grid export control
Dynamic export limitation
Point of connection (POC)
Energy management system (EMS)
Distributed energy resources (DER)
Battery energy storage system (BESS)
Self-consumption
Grid connection agreement