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

How do you install a home battery under the AREI? This guide covers circuit, isolation point, single-line diagram, backup operation and grid operator registration.

Published on 2 June 2026 Updated on 5 October 2026 11 min

The AREI has no dedicated chapter for household home batteries – the general provisions of Book 1 apply: protection against electric shock, overcurrent protection, isolation and overvoltage protection. The actual design follows from AC or DC coupling, the inverter, grid-parallel operation, backup, manufacturer data and the grid operator's connection procedure. This guide gives you a documented review path from protection concept through the single-line diagram to registration.

Why a Home Battery?

A battery stores surplus energy and delivers it later. How much grid import or cost it actually saves depends on measured load and PV profiles, usable capacity, efficiency, control strategy, tariff, ageing and operating mode. Fixed savings or a payback period can only be supported with time-series data and a dated tariff model.

The regulatory picture is clear: Chapter 7.103 covers industrial accumulator batteries and explicitly excludes batteries and chargers used in household installations (Section 7.103.1). For a home battery, the general parts of Book 1 therefore apply. Where the battery is coupled with a PV installation, Chapter 7.112 (household 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 a source in the installation design. Circuit arrangement, overcurrent protection, conductor section, RCD type and switching rating follow from 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” do not survive a review. Integrated residual-current monitoring counts only as far as the exact device documentation and the rules allow.

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. The diagram shows every actual isolator and its assignment; you prove its suitability with the device data.

Surge Protection (SPD)

AREI 4.5.1 sets the principle: persons and property are protected, according to good practice, against the harmful effects of overvoltages, for example from atmospheric phenomena or switching. It does not mandate a specific SPD type. A surge protection device at the AC connection is good practice for battery systems, and on the DC side as well – especially with outdoor cabling. Type and location follow from the risk assessment and manufacturer data.

Location and ventilation for lithium batteries

Location, temperature limits, clearances, ventilation and fire or escape-route conditions follow the actual battery technology, manufacturer instructions and the project risk assessment. There is no universal 35°C threshold, and not all products share one cell chemistry. Retain the product type, operating limits and installation manual in the dossier.

Integration in the Single-Line Diagram

The single-line diagram shows the home battery with both of its 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 installation:

  • Hybrid inverter → AC disconnect switch → MCB → Distribution board
  • Where the way sits in the board – upstream or downstream of which RCD – follows from the protection concept, earthing system and manufacturer data. There is no standard position “directly after the main switch”.

Representation in the Diagram

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

  • battery symbol (per IEC 60617 or clearly defined in the legend);
  • inverter symbol;
  • disconnect switch;
  • associated MCB and RCD.

Backup / Emergency Power Function

Many home batteries offer a backup function: when the grid fails, the battery keeps supplying selected circuits.

Transfer and island operation

A backup function requires a documented transfer and islanding concept. Depending on the system, the inverter handles it internally or external switching equipment does; a marketing label alone proves neither safe grid separation nor permissible island operation:

  • Automatic Transfer Switch (ATS): a documented internal or external arrangement changes to island 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 the boundary of the backed-up section on the single-line diagram. Which conductors are actually switched follows from the earthing system, neutral treatment, manufacturer evidence and grid-operator conditions. The goal is always the same: no dangerous backfeed into the isolated grid. “Always all-pole” is not a reliable standalone rule without that topology.

Warning signs

Markings make the actually possible feed-in and island states understandable. Position and wording follow from the real installation concept. For the PV part of a coupled installation, Section 7.112.2 requires warning signs stating “Do not disconnect under load” and “Electrical installation always live”; that does not translate into a standard battery sticker at two fixed locations.

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 an 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: bring the single-line diagram and situation plan up to the installed state; the competent operator confirms the submission package
  • Electrical inspection: the nature and scope of the alteration, together with Book 1, determine whether and which new inspection 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 at least AC active and apparent power, permitted phases, battery-voltage range, usable capacity, protection functions, firmware variant, parallel and backup behaviour, and expansion conditions.

An economic calculation needs project-specific inputs:

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

scenario duration = investment / cautiously estimated annual net effect

Both are scenarios, not forecasts. Calculate over several years with measured load and generation profiles, usable rather than nominal capacity, charge and discharge losses, power limits, degradation, warranty terms and a transparent tariff path. Regional incentives and network charges change over time; check them immediately before the 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 each keeps its own electrical limits and manufacturer conditions. With AC coupling, a separate battery inverter feeds the AC side. The power of every source stays visible in the connection assessment.

Mark each item as known, taken from manufacturer evidence or still to verify. The most important are:

  • rated power and maximum current per mode;
  • number of phases and intended phase allocation;
  • cable type, conductors, cross-section and installation method per segment;
  • overcurrent, residual-current and surge protection with their characteristics;
  • isolation points on the AC and DC side;
  • meters, current transformers or control contacts for power limitation;
  • firmware or variant covered by the homologation;
  • identification of grid-parallel and island paths.

This structure pays off in maintenance. 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 are designed explicitly. Terms such as backup, EPS and whole-home backup are not interchangeable legal categories.

Create a load list for the backed-up section: lighting, communication, refrigeration or heating have different priorities and starting loads. Identify the backed-up circuits on the situation plan and determine whether a separate board or selective transfer is used. The responsible professional ensures that no dangerous backfeed into an isolated distribution grid is possible.

Prepare the inspection and registration package

The dossier holds more than a printout: updated single-line diagram and situation plan, product data, installation and protection instructions, Synergrid evidence for the exact variant, grid-interface settings, inspection report and regional registration confirmation. Record who carried out the installation and which parameters were confirmed at commissioning.

In Flanders, Fluvius explicitly links storage registration with AREI inspection and Synergrid technical conditions. Wallonia and Brussels have their own competent operators and procedures, so you do not copy Flemish thresholds or sequencing without checking the connection location. The competent body for the connection address at the time of registration is decisive.

Common documentation failures

  • Battery and inverter merged into one symbol without electrical ratings.
  • AC- and DC-coupled variants with a similar product name mixed up.
  • Backup shown without the grid separation.
  • C10/26 checked by brand instead of model and variant.
  • A manufacturer example of breaker or RCD selection applied to a different earthing system.
  • The old diagram kept in the dossier after an inverter replacement.
  • An economic calculation based on nominal capacity, ignoring losses and ageing.

A clearly marked open point always beats a plausible but invented value.

Home batteries and PlanElec

PlanElec connects floor plan, electrical topology, distribution board and document exports in one project; for PV, strings, inverter and source protection are fully structured. Its data model can already account for several sources in the current path. Home batteries, however, are not yet a fully released workflow with their own palette, properties, rendering and export. For the battery, that means: you document the protection and isolation concept, backed-up section and registration from the manufacturer documents, and a battery symbol on the plan is not yet a verified battery design. The roles are clear: the AREI/RGIE self-check shows you findings within the supported rules, and the official inspection is carried out by the approved inspection body.

Current primary sources

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.

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