Combining Solar PV and an EV Charger on a Single-Line Diagram

On a single-line diagram, solar PV and an EV charger are two separate branches of the same distribution board. The inverter feeds in on its AC side; a normal charger draws energy through its own final circuit. An energy manager measures and controls both, but never puts them in series. That is how you draw them: two outgoing ways, clear power-flow directions, protection in the right place and load management shown as control.

A strong combined diagram shows sources, possible current directions, protection boundaries and measuring points. Anything only the design calculation, the manufacturer or the network operator can confirm, you document as evidence first and enter afterwards.

Continue the example: add EV1 to DB1

In the shared fictional job from the PV guide, S1 and S2 remain connected to DB1 through INV1. EV1 is a new unidirectional charging point at the parking space. Trace its branch to the actual connection in DB1; EV1 is not in series with INV1. The names explain the case without prescribing mandatory references.

The PV situation plan locates the same references. Use the installation planning guide to review the entered electrical connections in the model. You prove conductor and equipment current capacity with sizing and datasheets, not with a value shown by load management.

Inventory three related systems

Separate these levels first:

1. Grid and main distribution: connection, meter, main protection, earthing and relevant boards.
2. PV generation: modules or strings, DC components, inverter, AC protection and point of connection.
3. Charging load: dedicated circuit, overcurrent protection, residual current device (RCD), cable, connection point and any load control.

If the manufacturer specifies a different approved system concept, such as a bidirectional charger or an integrated hybrid unit, you draw exactly that topology. Model, firmware and system documentation then go into the dossier.

A typical common AC topology

A conventional installation looks like this in simplified form:

Distribution grid ↔ meter ↔ main board
                             ├─ PV AC branch ↔ AC protection ↔ inverter ↔ PV DC side
                             └─ charging branch → protection → cable → charger → vehicle
                                              └─ metering/load control, if installed

The two-way arrow shows a possible energy direction; the protection details still sit at the device. A unidirectional wallbox is a load branch, and it stays one even when its software offers “solar surplus charging”. Do not draw it as a generator.

Document the PV branch completely

For household low-voltage PV installations up to 10 kVA, Chapter 7.112 of AREI Book 1 V06 adds specific measures to the general rules: marking of DC conductors and live AC conductors, warning signs (“Do not disconnect under load”, “Electrical installation always live”) and earthing of the module frames unless the manufacturer forbids it (Section 7.112.2). Make the installed chain traceable:

• PV generator and relevant string or module arrangement;
• DC cables, polarity and cross-section;
• DC isolation and protection when installed or integrated;
• exact inverter model and maximum AC output;
• AC cable, overcurrent protection, RCD and other designed protection;
• precise connection point in the board;
• associated warnings and identification.

The PV system diagram guide covers this branch in more detail. Enter the manufacturer's actual data rather than a generic “PV protection” box.

Keep the charger on its dedicated circuit

AREI 7.22.3 requires a dedicated circuit for every connection point of a charging station, and connecting a charging station to the fixed installation through a plug and socket is prohibited. Where protection relies on automatic disconnection, 7.22.4.1 b requires each dedicated AC circuit to be protected individually by an RCD of no more than 30 mA. Protection must also keep working during insulation faults with a disturbing DC component: either through an RCD built for that purpose or through an RCD coordinated with a residual direct current detection device that takes the charger out of service. Under 7.22.4.2, each dedicated circuit also has its own overcurrent protection. These devices may sit in the board, in the charger or in a combination of both.

Show at least:

• circuit reference and phases;
• overcurrent device, number of poles and rated current;
• RCD type, rated residual current and any coordinated DC detection;
• cable type, number of conductors and cross-section;
• charger and number of connection points;
• rated power or maximum charging current;
• fixed control, metering or switching components.

If the charger is installed outdoors, 7.22.5.1 requires at least IP44 for the equipment. The acceptable combination follows from AREI, product standards and the exact manual together. RCD Type A versus Type B gives you the background; approval of the specific charger comes from its documentation.

Put energy management in the right place

Solar surplus charging or import limitation needs measurement and control. A system can include an energy meter, current transformers, controller, data link and controllable charger. Place the electrically relevant fixed parts where they are actually connected:

• measuring point at the supply or relevant board;
• current transformers with correct phase and direction;
• controller supply;
• contactor or control contact if it performs electrical switching or enabling;
• data link only as far as needed to explain the function.

A dashed line separates communication from power conductors; define it in the legend. “100% solar” does not belong on the diagram: production, building load, vehicle demand and control strategy change constantly.

Phases and power balance

Draw the real phase allocation of inverter and charger. A single-phase inverter and a three-phase charger do not become one branch because a meter nets their energy. A software current limit controls operation; cable sizing and overcurrent protection are still proven separately.

The cable cross-section and breaker relationship is therefore established fully and separately for the PV and charging branches.

The design review checks, among other things:

• supply capacity and permissible phase loading;
• simultaneous generation and demand;
• busbar and upstream device loading for every possible current direction;
• short-circuit, selectivity and voltage-drop conditions;
• measuring ranges and manufacturer limits of the control system.

The diagram records the chosen result; it is not the calculation itself.

Treat bidirectional charging separately

If the charger can export energy from the vehicle to the installation or grid, it is no longer only a load. AREI 7.22.5.4 then requires compliance with the rules for distributed generation units – protection against electric shock, overcurrent protection and safety disconnection – and the warning “Caution: possible feedback of electrical energy into the installation” on the charger and on the boards that supply it. Synergrid states that bidirectional, or technically bidirectional-capable, charging infrastructure falls under C10/11 and C10/26 approval; purely unidirectional chargers do not.

Show directions, isolation and protection functions exactly according to the approved system concept. A normal wallbox diagram does not fit Vehicle-to-Home or Vehicle-to-Grid.

Situation plan and dossier

Locate modules, inverter, relevant isolators, boards, fixed metering, charger and associated parking space. Repeat the circuit references from the single-line diagram. Datasheets, declarations, settings and later changes belong in the installation dossier.

Your final review confirms:

• the diagram, board labels and as-built installation agree;
• both branches can be traced to their common point;
• every energy-flow arrow points the right way;
• protection sits on the correct side without fictitious duplicates;
• load management is shown as control, never as protection;
• the charging function is clearly identified as unidirectional or bidirectional.

Carry later changes through the whole system

Combined systems often change after first handover: a different inverter, more panels, a second charging connector, a home battery or a new metering method. Update more than the device name; follow every affected branch back to the common board. How to integrate a home battery as a source in the installation is covered in Home battery and AREI.

Record the added source or point, new AC values and possible directions, revised protection, sensor position and phases, cables, board ways and labels. A software limit always travels with the device version and stored settings. A battery or bidirectional vehicle is not an invisible app feature: as soon as energy from another source can reach the fixed installation, source, isolation, protection and warnings are in the technical documentation. Archive the old drawing and identify the current revision unambiguously.

Worked case: adding a second charging point to existing PV

A building already has a PV inverter and a unidirectional wallbox; now a second connection point is added. Do not just copy the first symbol. Establish whether this is another device, one station with two connection points or a different manufacturer architecture, and where overcurrent protection and RCD actually sit. AREI 7.22.4.2 allows shared overcurrent protection for several connection points that are not used simultaneously, provided each point keeps the required protection – for example when the rated current of the shared device does not exceed the lowest rated current of the connection points. That exception covers overcurrent protection only; it does not cover shared RCDs or cables.

Then update supply capacity, phase allocation and load management. The points may share the available power dynamically, but the drawing still identifies each one, its real electrical subdivision and its maximum permitted load. Current sensors match the measured conductors and direction. You prove the as-built wiring with the survey and device documentation, not with a software screen showing two parking bays.

Review the PV branch as well. If only demand changes, modules and inverter stay the same, but the common board and possible current directions may need reassessment. Adding a hybrid inverter or battery at the same time introduces another source or operating mode with its own protection, isolation and documentation logic.

Build an evidence chain for commissioning

Link every important boundary on the diagram to evidence: rating plate or datasheet for power values, manufacturer architecture for integrated protection, test records for the completed installation and a configuration export for relevant limits. Mark assumptions as open. An RCD type or DC detection is shown as installed only once device and installation confirm it.

During the final review, walk through several energy states:

1. charging at night without PV generation;
2. PV generation with low building demand;
3. PV and vehicle against a dynamic import limit;
4. loss of load-management metering or communication;
5. for bidirectional equipment, energy returning from the vehicle.

For each state, path, limit, protection and fail-safe behaviour follow from the design and manufacturer concept. The single-line diagram does not show every software decision, but it shows every electrically relevant component and every possible source direction.

Keep grid and product approvals distinct

AREI documentation, Synergrid type approval and the distribution system operator's procedure answer different questions. A well-designed protection concept does not prove C10/26 listing; a listed product does not prove correct installation in this building. Synergrid currently states that purely unidirectional chargers do not need C10/26 approval because of C10/11 ed.2.4; other technical or grid conditions may still apply. What to do if the device is not on the list is explained in Synergrid C10/26 list.

Keep model, firmware, uni- or bidirectional capability, network-operator correspondence and actual commissioning settings with the drawing revision. That shows which technical state an approval or inspection relied on.

Label the PV and charging ways in the board with the same references as the drawing. Where reverse power flow is possible, the required warning signs go on the locations actually affected; a note in the app is not enough. Before handover, compare every label, circuit reference, device type and energy direction with the final diagram.

Building the documents in PlanElec

In PlanElec, you record the PV and charging branches in one project model: strings per MPPT, inverter, AC isolation point and source protection on one side, the wallbox on its own circuit on the other. The single-line diagram and situation plan come from the same data and export as PDFs. The AREI/RGIE self-check flags, among other things, a wallbox without its own circuit, without a 30 mA RCD or without suitable protection against DC fault currents, and it shows unassigned strings. The roles are clear: the self-check shows you findings within the supported rules; protection coordination and grid permission are settled through your design and the network operator, and the official inspection is carried out by an approved inspection body.

Official sources

• AREI/RGIE Book 1 from the FPS Economy: Chapters 7.22 and 7.112 and Parts 3 and 9, reviewed at V06.
• Synergrid: decentralised generation unit approval: C10/11 ed.2.4, C10/26 and the distinction for bidirectional charging.

Technical review: 5 October 2026. Check current connection conditions with the network operator and manufacturer versions before execution.