Grid commissioning is the process of verifying that an EV charging site is correctly connected to the electricity network and meets the requirements of the Distribution Network Operator (DNO/DSO) and applicable grid code rules before (or as part of) energization. It confirms that the site’s electrical infrastructure, protection settings, metering, and control schemes operate safely and in accordance with the agreed connection offer.
What Is Grid Commissioning?
Grid commissioning focuses on the interface between a site and the utility network, not only the internal installation.
– Confirms the site is connected according to the approved design and connection agreement
– Verifies protective devices, earthing arrangements, and operational limits at the point of connection (POC)
– Demonstrates that any required limitation schemes (import/export caps) function correctly and fail safely
– Produces the documentation required for DNO/DSO sign-off and operational handover
Why Grid Commissioning Matters in EV Charging
EV charging sites can introduce high, continuous loads and, in mixed-energy sites, enable export capability through DER.
– Prevents unsafe energization and reduces the risk of faults affecting the wider network
– Avoids delays caused by missing evidence required by the DNO/DSO
– Confirms that site load behavior will not exceed contracted grid capacity
– Ensures compliance where export is possible (PV, BESS, V2G)
– Reduces early-life failures by validating protection coordination and real operating conditions
What Grid Commissioning Typically Includes
The exact scope depends on the connection type and site complexity, but usually covers:
Connection and documentation checks
– Verify as-built connection matches approved single-line diagram and DNO requirements
– Confirm supply rating, main protection, and any agreed site maximum demand limits
– Confirm labeling, isolation points, and access to utility metering where applicable
Protection and earthing verification
– Validate earthing system arrangement (TT/TN) and bonding integrity
– Verify protection device settings and coordination (main breaker, feeder protection)
– Confirm disconnection behavior under fault conditions aligns with requirements
Metering and measurement validation
– Confirm correct installation and configuration of site metering at the POC
– Verify measurement direction (import/export) where relevant
– Validate any CT/measurement points used for control schemes or reporting
Control schemes and limitation tests (when required)
– Test dynamic load management if it is part of the agreed maximum demand strategy
– Test dynamic export limitation or customer limitation schemes where export is present
– Confirm fail-safe behavior during comms loss or controller failure
Functional energization checks
– Confirm stable voltage, phase sequence (where relevant), and safe energization sequence
– Validate charger group behavior under realistic load conditions (multi-charger simultaneity)
– Confirm alarms, monitoring, and event logging for operational readiness
Grid Commissioning vs Electrical Commissioning
They overlap but have different emphasis.
– Electrical commissioning verifies the full site installation is safe and operational (DBs, circuits, RCDs, charger function)
– Grid commissioning verifies the site’s compliance at the grid interface and DNO/DSO acceptance requirements
Typical Deliverables
Grid commissioning usually produces a documented evidence pack.
– DNO/DSO commissioning sign-off forms (where applicable)
– As-built single-line diagram and protection schedules
– Test records for earthing, protection verification, and metering checks
– Control scheme test evidence (import/export caps, fail-safe behavior)
– Commissioning report with dates, responsible parties, and measured results
Common Pitfalls
– Treating DNO/DSO sign-off as a formality and missing required documentation
– Not testing under realistic simultaneity, so the site exceeds limits after go-live
– Incorrect measurement point for limitation schemes, causing non-compliance at the POC
– Poor coordination between installer, CPMS/EMS provider, and DNO requirements
– Design changes made on site that are not reflected in as-builts and test evidence
Related Glossary Terms
Grid connection
Distribution Network Operator (DNO)
Grid code compliance
Grid capacity
Grid capacity assessment
Electrical commissioning
Dynamic load management
Dynamic export limitation
Earthing system