The terms that determine what you sign and what you pay for
Published: 26 July 2026 · Last updated: 26 July 2026
Two offers for the same charging infrastructure can differ substantially in price — with the same number of charge points and the same total rated power. The difference often sits in details that are stated accurately, but in terms the buyer is not expected to know: the type of residual current protection, the presence of a certified meter, the communication protocol supported.
Charging infrastructure is described using vocabulary drawn from three separate domains: electrical engineering, telecommunications, and energy regulation. In an offer or tender document they appear together — and the distinction between two terms often determines the price, or what you actually receive.
This glossary is organised by decision area rather than alphabetically. Terms are grouped according to what they govern: how the system communicates, how energy is managed, what equipment is installed, and how access and costs are controlled. The aim is not completeness, but usefulness at the point of decision.
1.Communication and connectivity
Communication protocols rarely appear as a priority in a technical specification. They nonetheless determine whether the infrastructure can be managed centrally — or whether each hardware brand remains in its own portal, with its own interface and its own reporting.
This is a decision made once — and felt at every subsequent expansion.
An open communication standard between the charging station and the management platform, published by the Open Charge Alliance. It defines how the platform starts and stops sessions, sets current limits, reads diagnostics, and updates firmware.
The current versions are OCPP 1.6 J (the most widely deployed) and OCPP 2.0.1 (newer, with extended security and charging control functions).
What it means in practice: if a station supports OCPP, it can be managed by a platform other than the manufacturer's portal — for example Qerra OS. If it doesn't, you remain inside a closed system.
A standard for exchanging data between charging network operators and mobility service providers. It underpins roaming: a session on a third-party network is recorded and billed through your own provider.
Distinct from OCPP. OCPP connects the station to the platform. OCPI connects platforms to each other.
An industrial communication protocol used widely in building and industrial control systems. In charging infrastructure it connects to energy meters, building energy management systems (BEMS), photovoltaic inverters, and battery storage.
Without a Modbus connection, the platform sees only the charging stations. With it — for example Qerra OS — the platform sees total site consumption, a precondition for genuine power management.
The charging station contains a modem and SIM card. Suitable for sites without existing network infrastructure. Signal coverage should be verified before installation — weak reception is a common source of communication interruptions.
A wired connection to the site network. More stable than mobile connectivity and without recurring data costs. The preferred option at depots and buildings where cabling is available.
Communication between the vehicle and the charging station through the charging cable itself, using high-frequency signals. It underpins the ISO 15118 and DIN 70121 protocols and is used primarily in DC charging under the CCS standard.
A standard for automated, encrypted communication between vehicle and station. Under Plug & Charge, the vehicle identifies itself when the cable is connected — no card or application required. The session starts and is billed automatically.
2.Energy and grid capacity
These terms carry the most direct financial consequence. Available capacity determines how many vehicles a site can serve. How that capacity is managed determines whether a new grid connection becomes necessary — a procedure with timelines and costs set by the condition of the local network, not by the project contractor.
The maximum power a site is entitled to draw under its agreement with the distribution network operator. This is a contractual limit, not a physical property of the cable.
Exceeding it results in penalties or triggers protective devices. Charging infrastructure shares this capacity with every other consumer on site — which is why real-time energy control matters.
The procedure for a new connection to the distribution network, or for increasing existing contracted capacity. It involves submitting documentation to the network operator, obtaining a connection statement, and concluding a contract.
Timelines and costs depend on the capacity available in the specific network and are determined by the operator, not by the project contractor. See how we work.
Operating multiple charging stations within a limited contracted capacity. If four 22 kW stations represent 88 kW combined, and the site has 43 kW available, the system must limit simultaneous draw.
Three principal approaches exist: reducing current across all stations, limiting the number of vehicles charging at once, or a combination governed by priorities. See Energy Control.
An extension of the above: the system measures actual total site consumption in real time and distributes the remaining capacity across the charging stations.
The distinction is substantial. Static management reserves a fixed share for charging. Dynamic management uses whatever capacity is free at any given moment — including capacity released outside working hours.
A measurement device at the site entry point or on individual sections. It gives the platform a real picture of load. Without it, dynamic management is not possible — the system cannot know how much capacity is free.
PV (photovoltaic system) — local electricity generation. BESS (Battery Energy Storage System) — local storage.
When included in the overall energy balance, generated or stored energy can be directed preferentially to charging sessions rather than exported to the grid.
kW is power — how fast energy flows at a given moment. It determines connection sizing and charging speed. kWh is energy — the quantity delivered. It determines the bill.
Conflating the two is the most common error when reading an offer. A 22 kW station does not consume 22 kWh — it consumes 22 kWh per hour at full output.
3.Equipment and safety
The terms in this section describe physical equipment and the standards applying to it. This is where most hidden differences between two offers sit — components that do not appear in a summary specification, but are mandatory and carry a cost.
Charging with alternating current. Conversion to direct current is performed by the vehicle's onboard charger, which — not the station alone — limits the achievable power.
Typical ratings: 7.4 kW, 11 kW, 22 kW. Suited to dwell times of several hours: overnight depot charging, workplaces, car parks.
Charging with direct current. The converter sits in the station rather than the vehicle, permitting substantially higher output — from 50 kW to above 350 kW.
More expensive to install and more demanding on grid capacity. Appropriate where dwell times are short and rapid turnaround is an operational requirement.
The international standard for conductive charging of electric vehicles. It defines safety requirements, vehicle-to-station communication, and charging modes.
A protective device against electric shock. In charging applications, a standard Type A device is not sufficient on its own, because charging can generate DC residual currents that it does not detect in time.
The applicable options are Type B, Type A-EV with DC detection, or Type A combined with a station providing integrated DC residual current protection.
This element is frequently a hidden source of price difference between two offers.
A two-digit code indicating resistance to environmental conditions. The first digit covers solid particles and contact, the second covers water.
IP44 — protection against objects larger than 1 mm and splashing water from any direction. IP54 — full protection against contact, limited dust ingress, resistance to splashing water.
For open car parks and high-traffic depots, the higher rating is a practical requirement.
A meter compliant with the European Measuring Instruments Directive. Required where measured energy is used for billing — for example when reimbursing employees or charging tenants.
If charging will be re-invoiced, the presence of an MID meter in the station should be verified at the offer stage.
4.Access, reporting, and roles
Once commissioned, charging infrastructure becomes an administrative process. These terms describe who charges, under what conditions, and how costs reach the correct department — without manual reconciliation at the end of each month.
Identification via card or tag. A session starts only after the user is recognised. It enables user groups, differentiated access rules, and cost tracking by individual, department, or vehicle.
The ability for a user registered with one provider to charge on another provider's network. For a corporate fleet this means public charging sessions enter the same reporting framework as depot and workplace charging.
The current battery charge level, expressed as a percentage. Charging speed falls significantly above roughly 80% — a factor with direct bearing on operational scheduling.
The European Union's Alternative Fuels Infrastructure Regulation. It sets requirements for publicly accessible charging infrastructure, including provisions on payment methods and price transparency.
Bidirectional charging, in which the vehicle battery can return energy to the grid or to the site. Requires compatibility in both vehicle and station. Deployment remains limited and depends on the regulatory framework in each country.
Why the ordering matters
The terms in this glossary are not independent of one another.
Contracted capacity determines whether load management is needed. Load management requires measurement of actual consumption. Measurement requires a Modbus connection. Centralised control requires OCPP. Departmental cost reporting requires RFID and an MID meter.
Individually, each is a technical detail. Together they determine whether the infrastructure functions as a system — or as a collection of separate devices, each with its own interface.
The choice is therefore not between individual components. It is between two approaches to design.