What a Distribution Network Operator Is
A Distribution Network Operator (DNO) is the company responsible for operating, maintaining, and upgrading the electricity distribution network (typically the medium- and low-voltage grid) in a specific geographic area. The DNO owns and manages assets like substations, transformers, poles, cables, and feeders that deliver electricity from the transmission system to homes, businesses, and charging sites.
Why DNOs Matter for EV Charging
For EV charging projects, the DNO is a key stakeholder because they control what power is available at a site and under what conditions. DNO involvement often determines:
– Whether a site has enough capacity for new chargers
– How quickly a project can connect to the grid (lead times can be significant)
– The technical requirements for protection, earthing, and metering
– The need (and cost) for network reinforcement or a new transformer
– Export permissions if the site includes DER (solar PV, BESS) or bidirectional charging
What DNOs Typically Do in Charging Projects
DNO responsibilities and touchpoints commonly include:
– Connection offers: assessing capacity and issuing terms/costs to connect
– New connections and upgrades: increasing supply, adding substations, upgrading cables
– Service alterations: moving/upsizing cut-outs, changing service heads (market-dependent)
– Technical approvals: protection coordination, fault level checks, earthing compatibility
– Planned outages: coordinating shutdowns needed for tie-ins
– Ongoing network reliability: managing faults and restoration on the distribution grid
DNO vs Supplier vs TSO
These roles are often confused:
– DNO: owns/operates the local distribution network (wires, substations)
– Electricity supplier: sells energy and manages billing contracts (retail)
– TSO (Transmission System Operator): runs the high-voltage transmission grid (national backbone)
Common DNO-Related Constraints for EV Charging
EV charging can trigger constraints that require DNO action:
– Limited local transformer capacity
– High peak demand creating voltage drop or thermal overload
– Long reinforcement timelines
– High connection costs for fast charging or large depots
– Restrictions on export for sites with PV/BESS
Practical Tips When Planning a Charging Site
– Engage the DNO early, before finalizing charger quantity and power levels
– Design for scalability (spare ducts, DB capacity, staged rollout)
– Use load management and depot scheduling to reduce peak import needs
– Consider DER (PV/BESS) if grid upgrades are expensive or slow
– Align acceptance testing and commissioning with DNO outage windows
Related Terms for Internal Linking
– Grid connection
– Capacity reservation planning
– Grid congestion
– Distribution board (DB)
– Demand charges
– Load management
– Distributed energy resources (DER)
– Battery energy storage system (BESS)