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

An energy app may show rooftop solar flowing straight into a car. Electrically, the PV installation and charger are normally two separate branches of the same distribution system. The inverter injects on its AC side; a conventional charger draws power through a dedicated final circuit. An energy-management system can measure and control both, but it does not turn them into a direct series connection.

A dependable combined diagram shows sources, possible power directions, protection boundaries and metering points. It avoids claiming a guaranteed solar share, available capacity or network approval that only the actual design and relevant parties can establish.

Inventory three related systems

Separate the installation into:

1. Grid and main distribution: service, meter, main protection, earthing and relevant boards.
2. PV generation: modules or strings, DC components, inverter, AC protection and connection point.
3. Charging load: dedicated circuit, overcurrent and residual-current protection, cable, charging point and optional load control.

An integrated hybrid product or bidirectional charger may use a different topology. Draw it only from the approved manufacturer system design and retain model, firmware and configuration evidence in the dossier.

A typical common AC topology

A conventional arrangement can be simplified as:

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

The double arrow indicates a possible direction of power; it is not a protective function. A unidirectional wallbox remains a load even when its software offers “solar surplus charging”.

Document the PV branch completely

Chapter 7.112 of AREI Book 1 V06 adds requirements for domestic low-voltage PV installations up to 10 kVA. The drawing and dossier should make the installed chain traceable:

• PV generator and relevant string or module arrangement;
• DC conductors, polarity and cross-section;
• installed or integrated DC isolation and protective functions;
• exact inverter model and maximum AC output;
• AC cable, overcurrent device, RCD and other designed protection;
• clear connection point at the distribution board;
• warnings and identification belonging to the installation.

The PV system diagram guide covers this branch in more detail. A generic label such as “PV protection” is not enough when the actual functions remain unknown.

Keep the charger on its dedicated circuit

AREI Chapter 7.22 requires a separate circuit for every connection point of a fixed conductive charging installation. Every separate AC circuit is individually protected by an RCD rated at no more than 30 mA. Protection must remain effective with disruptive DC components, using a suitable RCD or a coordinated combination with DC residual-current detection. Each separate circuit also receives appropriate overcurrent protection.

Show at least:

• circuit reference and phases;
• overcurrent device with pole count and rating;
• RCD type and any coordinated DC detection;
• cable type, conductor count and cross-section;
• charger and number of connection points;
• rated power or maximum charging current;
• fixed control, metering or disconnection equipment.

The acceptable combination depends on AREI requirements, product standards and the exact manual. RCD Type A versus Type B provides background but is not approval for a particular charger.

Put energy management in the right place

Solar-surplus charging or grid-import limiting needs measurements and control logic. A system may include an energy meter, current transformers, controller, communication and a controllable charger. Place electrically relevant fixed components where they actually connect:

• measurement point at the service or relevant board;
• current sensors with correct phase assignment and orientation;
• controller supply;
• contactor or control contact if it performs electrical switching or enablement;
• data connection only to the extent needed to understand the function.

A dashed line can distinguish communication from power conductors when defined in the legend. Avoid “100% solar charging”: generation, building load, vehicle demand and control strategy continually vary.

Phases and power balance

Show the real phase allocation of inverter and charger. A single-phase inverter and three-phase charger do not become one electrical branch because a meter nets their values. A software current limit also does not replace conductor sizing or overcurrent protection.

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

The design should consider:

• service capacity and permitted phase loading;
• simultaneous generation and consumption;
• switchboard bus and upstream-device loading for possible power directions;
• fault current, selectivity and voltage-drop conditions;
• measurement range and manufacturer limits of the control system.

The diagram records the selected design; it is not the design calculation itself.

Treat bidirectional charging separately

If a charger can return vehicle energy to the fixed installation or grid, it is no longer only a load. AREI 7.22.5.4 then invokes requirements for decentralised generation and warnings at affected chargers and distribution boards. Synergrid states that bidirectional, or technically bidirectional-capable, charging infrastructure falls within C10/11 and C10/26 type approval; purely unidirectional charging does not.

Show power directions, isolation and protective functions according to the approved system concept. Do not reuse a normal wallbox topology for Vehicle-to-Home or Vehicle-to-Grid.

Situation plan and dossier

Locate modules, inverter, relevant isolators, boards, fixed metering, charger and its related parking space. Repeat the same circuit references used on the single-line diagram. Keep datasheets, equipment declarations, settings and subsequent changes in the installation dossier.

Before finalising, check that:

• the drawing, board labels and as-built installation agree;
• both branches can be traced to their common point;
• every energy-flow direction is correct;
• protection is drawn on the correct side without invented duplicates;
• load management appears as control, not a substitute for protection;
• unidirectional or bidirectional capability is explicit.

Carry later changes through the whole system

Combined energy systems often evolve after handover. A replacement inverter, extra array, second charging point, battery or new metering method can change the topology. Do not edit only the equipment label: trace every modified branch back to the common board.

Record the additional source or connection point, changed maximum AC value and power direction, revised protection, sensor position and phase mapping, conductor data and physical labels. Keep software limits with the equipment version and configuration evidence. A battery or bidirectional vehicle is not an invisible app feature; once another source can energise the fixed installation, its source, isolation, protection and warnings must be technically traceable. Archive the superseded drawing and mark the current revision clearly.

Worked case: adding a second charging point to existing PV

Suppose a building already has a PV inverter and a unidirectional wallbox, and a second connection point is added later. Do not begin by copying the first symbol. Establish whether the project uses another charger, one station with two connection points or a different manufacturer architecture, and locate the actual overcurrent and residual-current protective functions. Chapter 7.22 contains a narrow option for common overcurrent protection where several connection points are not used simultaneously and the necessary protection remains effective for each point. It is not a general permission to share circuits or RCD protection.

Update service demand, phase assignment and load management next. The two points may share capacity dynamically, but the drawing still has to identify both connection points, their real electrical subdivision and the maximum enabled load. Current sensors must match the measured conductors and orientation. A software screen showing two parking bays is not evidence of the as-built wiring or integrated protection.

Revisit the PV path as well. If only consumption changes, modules and inverter may remain untouched, but the common board and possible current directions may need a new assessment. If a hybrid inverter or battery is added at the same time, it introduces another source or operating mode and needs its own traceable protection, isolation and documentation concept.

Build an evidence chain for commissioning

Link each important boundary on the drawing to evidence: a nameplate or datasheet for power values, a manufacturer system diagram for integrated protective functions, test records for the installed work, and a configuration export for relevant limits. Mark assumptions as open. Do not draw an RCD type or DC residual-current detection as installed until the exact device and arrangement support that statement.

At final review, walk through several energy-flow cases:

1. vehicle charging at night with no PV generation;
2. PV generation with low building demand;
3. PV and charging operating against a dynamic import limit;
4. loss of load-management measurement or communication;
5. for bidirectional equipment, energy returning from the vehicle.

For each case, the power path, limit, protection and fail-safe response should be explainable from the designed system and manufacturer concept. The single-line need not reproduce every software decision, but it must not hide an electrically relevant component or possible source direction.

Keep grid and product approvals distinct

AREI documentation, Synergrid type approval and the relevant distribution-system operator's connection process answer different questions. A competently designed AREI protection concept is not evidence of C10/26 listing, while a listed product does not prove correct installation in this building. Synergrid currently states that purely unidirectional chargers do not require C10/26 approval under C10/11 ed.2.4; other technical or network conditions can still apply.

Record equipment model, firmware, uni- or bidirectional capability, grid-operator correspondence and actual commissioning settings with the drawing revision. This makes clear which technical state an approval or inspection considered.

Building the documents in PlanElec

In PlanElec, you can record PV and charging branches, align them with the situation plan and export both PDFs. The indicative self-check can flag supported data. PlanElec does not perform full protection coordination, grant network permission, certify AREI compliance or produce an official inspection report.

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 date: 29 August 2026. Recheck current connection conditions and manufacturer versions before implementation.