Why does the grid connection decide so much?
A meeting with the grid operator. The retail park's existing connection has 250 kVA, enough for lighting, shops and a few AC charge points.
The hub would need about 1.2 MW on top.
The questionWhy does the connection decide what the hub can be, and when it can open?
fits almost any building connection
more than many whole buildings draw
at low voltage, a thick bundle of cables
the same power at medium voltage
Computed: current equals power divided by √3 times voltage. At 20,000 volts, the same power needs one fiftieth of the current.
- Street grid400 V
- Connectionshared with the building
- Chargersa few hundred kW at most
- Medium-voltage line10 to 20 kV
- Own transformeron site
- Switchgearprotection and metering
- Chargersmegawatts possible
Voltages and limits differ by country and grid operator; the principle is the same everywhere.
What the grid operator does
The checks whether its grid can carry the new load, offers a connection and builds its part. EU law requires Member States to make connecting charge points easier and requires grid operators to cooperate on a non-discriminatory basis with any company that builds or runs them.
Grid operators themselves may, in principle, not own or operate public charge points. Their job is the connection, not the charging.
Time and size
- Time. A new connection needs planning, a transformer and often cable works in the street. That makes it one of the longest steps of a project.
- Size. The connection sets the ceiling for the hub's total power. A larger connection costs more, a smaller one limits the hub.
- Sharing. With , the chargers share a connection that is smaller than the sum of their ratings, the subject of its own path.
Check your understanding
3 questions. Answer all of them to complete this stop. Each answer explains itself.
Why do fast-charging hubs usually connect at medium voltage?
At 20 kV, a megawatt needs about 35 A; at 400 V, it would need about 1,700 A.
What does EU law require of grid operators towards charging companies?
Article 33 of the Electricity Directive: cooperation on a non-discriminatory basis. Owning or operating public chargers is, in principle, not their role.
How can load management help with the grid connection?
Not every charger runs at full power at the same time. Load management divides what the connection offers.
- Load management Shares a site's grid connection between the cars charging at the same time. EV charging fundamentals, stop 04 Glossary
- DSO Distribution system operator: runs the local power grid and connects charging sites to it. EV charging fundamentals, stop 07 Glossary
- Medium voltage The grid level of roughly 10 to 20 kV between the high-voltage network and the 400-volt street grid; large charging hubs usually connect here, with their own transformer. Glossary
- EUR-Lex: Directive (EU) 2019/944 on common rules for the internal market for electricity, Article 33. https://eur-lex.europa.eu/eli/dir/2019/944/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.
- EUR-Lex: Directive (EU) 2019/944 on common rules for the internal market for electricity, Article 33. https://eur-lex.europa.eu/eli/dir/2019/944/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.