Home Battery and AREI: Correctly Integrating Battery Storage into Your Electrical Installation

A home battery can shift energy in time, but it is not a standard add-on that can be designed from capacity alone. AC or DC coupling, inverter, parallel operation, backup, protection, manufacturer instructions and regional registration determine the project. This guide therefore provides a documented review path, not a compliance or return promise.

Why a Home Battery?

A battery can store surplus energy and deliver it later. Any reduction in grid import or cost depends on measured load and PV profiles, usable capacity, efficiency, control strategy, tariff, ageing and operating mode. Without time-series data and a dated tariff model, neither fixed savings nor a payback period is supported.

The AREI has no dedicated chapter for domestic home battery storage — the general rules apply (protection against electric shock, overcurrent protection, isolation/safety disconnection). The dedicated battery chapter 7.103 (industrial accumulator batteries) explicitly excludes domestic installations. Where the battery is coupled with a PV installation, Art. 7.112 (domestic low-voltage photovoltaic installations ≤ 10 kVA) applies to the PV part; the battery itself does not fall under it.

AREI Requirements for Home Batteries

AC connection, protection and conductor

The battery or hybrid inverter is treated as a source in the installation design. Circuit arrangement, overcurrent protection, conductor section, RCD type and switching rating follow the equipment ratings, earthing system, installation conditions, manufacturer instructions and applicable AREI rules. Generic combinations such as “always 20 A on 2.5 mm²” or “three-phase always needs Type B” are unsafe shortcuts. Integrated residual-current monitoring counts only where the exact device documentation and rules allow it.

Disconnect Switch (Isolation Point)

The project needs a traceable isolation and switching concept. Which poles are switched, what may be integrated and where an additional isolator is required depend on topology, manufacturer evidence and the applicable provisions. Show actual isolators in the diagram; drawing one does not prove its suitability.

Surge Protection (SPD)

A surge protection device (SPD) is recommended at the AC connection. Art. 4.5.1 establishes the general principle that persons and property must be protected against overvoltages, but does not mandate a specific SPD type. On the DC side, an SPD is also advisable, especially for outdoor cabling.

Ventilation for Lithium Batteries

Location, temperature limits, clearances, ventilation and fire or escape-route conditions follow the battery technology, manufacturer instructions and project risk assessment. A universal 35°C threshold or the statement that all products share one chemistry would be inaccurate. Retain the product type, operating limits and installation manual in the dossier.

Integration in the Single-Line Diagram

The single-line diagram must correctly represent the home battery. The integration covers two sides:

DC Side

The direct current side shows the path from the battery pack through the battery management system (BMS) to the inverter:

• Battery → BMS → DC disconnect switch → Hybrid inverter
• For AC-coupled systems: Battery → dedicated battery inverter → AC connection

AC Side

The alternating current side shows the integration into the household network:

• Hybrid inverter → AC disconnect switch → MCB → Distribution board
• The connection is typically made after the main switch but before the individual circuit RCDs

Representation in the Diagram

In the single-line diagram, the home battery appears as its own branch, similar to the PV installation. The symbols include:

• Battery symbol (per IEC 60617)
• Inverter symbol
• Disconnect switch
• Associated MCB and RCD

Backup / Emergency Power Function

Many modern home batteries offer a backup function. When the grid fails, the battery continues to supply selected circuits.

Transfer Switch

A backup function requires a documented transfer and islanding concept. Depending on the system, the function may be internal to the inverter or implemented with external switching equipment; a marketing label alone proves neither safe grid separation nor permissible island operation:

• Automatic Transfer Switch (ATS): A documented internal or external arrangement changes operating mode under its approved conditions.
• Manual Transfer Switch: A changeover switch allows manual disconnection from the grid and operation in island mode.

Show the switching function and backed-up boundary on the single-line diagram. Which conductors must be switched follows from the earthing system, neutral treatment, manufacturer evidence and grid-operator conditions. The resulting design must prevent dangerous energisation of the isolated grid; “always all-pole” is not a reliable standalone rule without that topology.

Registration with the Grid Operator

Registration and connection procedures are regional and depend on the operating mode. Before ordering and commissioning, check the current process of the operator responsible for the address, particularly for equipment operating in parallel with the grid or technically capable of doing so:

• With existing PV installation: Modification notification — the installation is registered as PV + battery
• Technical data: Capacity (kWh), inverter power (kW), AC or DC coupling
• Homologation: C10/11 ed. 2.4 and C10/26 type approval apply to grid-parallel or technically capable generation units. Check model, variant and firmware with the Synergrid C10/26 check for home batteries
• Documents: Update the single-line diagram and situation plan to the installed state; confirm the submission package with the competent operator
• Electrical inspection: The nature and scope of the alteration together with Book 1 determine which new control step is required

Separate equipment selection from economics

Compare dated manufacturer data and the exact Synergrid listing, not a brand ranking that quickly ages. Record AC apparent and active power, phases, battery-voltage range, usable capacity, protection functions, firmware variant, parallel and backup behaviour, and expansion conditions.

An editable economic scenario is:

annual effect = avoided import + valued services − extra losses − running costs

scenario duration = investment / cautiously estimated annual net effect

These equations are not forecasts. Use measured load and generation profiles, usable rather than nominal capacity, charge/discharge losses, power limits, degradation, warranty terms and a transparent tariff path. Regional incentives and network charges are time-sensitive and must be checked immediately before a decision.

Build the documentation around energy paths

A useful diagram separates AC and DC as well as operating states. For every path, show source, conversion, protection, isolation and destination. In a DC-coupled system, the PV generator and battery share a hybrid inverter but retain different electrical limits and manufacturer conditions. With AC coupling, a separate battery inverter feeds the AC side. Source power must not silently disappear from connection assessment.

Mark each item as known, taken from manufacturer evidence or still to verify. Capture rated power and maximum current per mode, phase arrangement, cable type and installation method, protective-device characteristics, AC/DC isolators, metering or limiting controls, firmware reference and the distinction between grid-parallel and island paths. An inverter replacement may alter protection, connection power, homologation and notification even when battery capacity stays unchanged.

Backup is a separate design project

A product advertised as “backup” does not automatically supply the whole dwelling during an outage. Transfer arrangement, safe grid separation, neutral treatment, island earthing, selected loads, starting currents and behaviour at low state of charge all require design. Terms such as backup, EPS and whole-home backup are not interchangeable legal categories.

Create a load list for the backed-up section and identify those circuits on the situation plan. Determine whether a separate board or selective transfer is used. A competent person must ensure that no dangerous backfeed into an isolated distribution grid is possible.

Prepare the inspection and registration package

Retain updated diagrams, product data, installation and protection instructions, Synergrid evidence for the exact variant, grid-interface settings, inspection report and regional registration confirmation. In Flanders, Fluvius explicitly links storage registration with AREI inspection and Synergrid conditions. Wallonia and Brussels use their competent operators and procedures, so do not copy Flemish thresholds or sequencing without checking the connection location.

Current primary sources

• FPS Economy: AREI/RGIE books, Book 1 version 06, including the DC-system changes applicable from 1 April 2026.
• Synergrid: homologation of decentralised generation units, covering C10/11 ed.2.4 and C10/26 for grid-parallel or technically capable battery and hybrid inverters.
• Fluvius: storage-system registration, a regional primary source for Flanders.

PlanElec boundary

PlanElec currently connects floor plan, electrical topology and available exports in one project. Its technical model can represent sources, but battery, generator and V2G are not yet released as a complete palette, inspector, rendering and export workflow. A battery symbol or a self-check without findings therefore proves neither full battery coverage nor AREI compliance.

Pre-installation review list

1. Describe grid-parallel, zero-export and backup modes separately.
2. Record the exact inverter model, firmware and current Synergrid status.
3. Draw AC and DC coupling with every energy path, rather than only a battery icon.
4. Derive protection and isolation from manufacturer evidence and the applicable AREI provisions.
5. Keep cable and location data project-specific; do not copy them from an example.
6. Check effects on existing PV, metering, connection capacity and phase balance.
7. Confirm inspection and notification documents with the operator responsible for the address.
8. After commissioning, retain settings, signed diagrams, inspection report and registration confirmation.

Common documentation failures include mixing AC- and DC-coupled variants with a similar product name, checking C10/26 only by brand, omitting the transfer arrangement from a backup diagram, or retaining the old plan after an inverter replacement. Another failure is to treat a manufacturer example of breaker or RCD selection as a universal rule. A clearly marked open point is safer than a plausible but invented value.

Related articles:

• AREI Regulations 2026: What Has Changed?
• Dedicated Circuits: Which Appliances Need Their Own Circuit?
• Cable Cross-Section and Breaker: The Right Combination

Structure known project data in PlanElec and have protection, installation and registration reviewed professionally. Get started →