Germany assesses the same home battery twice, on two rulebooks that run in opposite directions. The unit certificate and VDE-AR-N 4105 govern the unit that feeds the network. §14a EnWG governs the devices that draw from it — and that is the one installers most often miss, because by the time it applies the job already looks finished.

In short: a battery that draws more than the framework threshold from the low-voltage network — on its own, or at a connection point already shared with a wallbox or heat pump — is a steuerbare Verbrauchseinrichtung, a controllable consumption device. It has to be registered with the network operator and made available for network-oriented curtailment; in return the customer's grid fee is reduced.

The rest of this article is the practical detail: what each obligation is, who owns it, and what it changes on the quote.

Two filings, two directions of current

Generation and storage unit Controllable consumption device
Governing rule VDE-AR-N 4105 connection rules §14a EnWG, network-oriented control
Document at the centre Unit certificate (Einheitenzertifikat) for the inverter Registration and control arrangement for the device
Filed by Registered electrical contractor Registered electrical contractor, for the plant operator
When Before commissioning At connection, before commissioning
The customer's benefit The unit may connect and export A reduced grid fee, on the modules below

Same address, usually the same operator, frequently a different department. An installer who completes the unit-certificate filing and closes the job leaves the second one open, because it belongs to the other side of the meter. The generation-side detail — the unit certificate, the operator's document list and the MaStR handover — is set out in our German grid-registration guide.

When a battery counts as a controllable consumption device

The framework defines a controllable consumption device by its power drawn from the network, not by its stored energy. The trigger value is a connection power above 4.2 kW at the low-voltage network; operators publish their own application of it, and several list storage explicitly alongside charging points and heat pumps.

Practical cases:

  • Grid charging above the threshold. A storage unit that can draw more than the threshold from the network is caught in its own right.
  • PV-only charging, or grid charging below the threshold. The unit may sit outside §14a on its own — but the operator determines that, not the datasheet.
  • A battery added to an address that is already a controllable device. If the house already has a wallbox or a heat pump, the connection point is already a controllable consumption device, and the new storage has to be integrated into the existing control arrangement rather than treated as a new one.

Two errors worth avoiding. First, reading 4.2 kW as a battery capacity: it is power at the connection point, so a 14.34 kWh wall unit is not automatically caught any more than a 5 kWh one is. Second, assuming the answer will repeat at the next address: the operator runs the check — often called a Betroffenheitsprüfung — and the technical arrangement differs between networks.

What that means for the specification you send us. The number the operator assesses is the unit's draw from the network — a datasheet figure in kW, not the kWh nameplate. In the Storage Wall series, capacities run from 2.56 to 14.34 kWh across four models; the charge and discharge power of each SKU is on its datasheet, which we provide on request.

What the customer receives: the three fee modules

The reduced grid fee is the counterpart for the customer accepting that the device can be curtailed during a network bottleneck. Operators offer a choice of modules, and each publishes its own prices:

Module What the customer accepts How it is credited
Module 1 No network-oriented curtailment; a flat reduction Lump sum credited via the grid fee
Module 2 No network-oriented curtailment Percentage reduction of the working grid fee
Module 3 Network-oriented curtailment of the device's draw Larger percentage reduction of the working grid fee

The percentages and the mechanics are set by each network operator and published in its price sheets and FAQs — take the current figures from the operator that serves the address, not from a template quotation. The module is a commercial decision for the customer; your job is to make sure the technical arrangement supports the one they choose.

What changes on the quote and on installation day

  • The control arrangement has to be agreed first. The operator defines the technical connection option for control, and it depends on how far the smart-meter rollout has reached in that network. Get it in writing before you buy control hardware, because the interim and target arrangements are not the same.
  • Registration is a step, not a footnote. Operators publish their own checklist for controllable devices, separate from the generation-side checklist. Build it into the schedule the way you build in the unit certificate.
  • The battery's own configuration matters. During a curtailment window, what the household experiences depends on how the hybrid inverter is set up. The pairing questions worth putting to any storage supplier are in our inverter-compatibility checklist; the hybrid inverter range we integrate covers the Huawei SUN2000 and Deye SG-series, single-phase 230 V, with CAN/RS485 communication to the battery.
  • It belongs in the customer conversation. A reduced grid fee and a curtailed charging window are two halves of one calculation. If you are presenting payback to a homeowner, the grid-fee line is part of it — our savings walkthrough sets out the other variables.

Three registers installers mix up

  1. The operator's connection file — unit certificate, protection settings, single-line diagram.
  2. The operator's controllable-device file — §14a registration and the agreed control arrangement.
  3. The Marktstammdatenregister — the Bundesnetzagentur's register, filed by the plant operator, and not a §14a document.

Keep them separate in the project file, and keep the operator's own checklists with them. Details and deadlines change; the operator's current documents are the version that governs.

Questions installers ask us

Does every home battery fall under §14a?

No. It depends on the power the unit — or the connection point it shares — draws from the network, and the operator makes the determination. Storage that charges only from the array often falls outside on its own; storage added next to a wallbox or heat pump usually does not.

Is this the same filing as the unit certificate?

No. The unit certificate describes the unit as it behaves on the network and belongs to the generation side. §14a registration is a consumption-side filing with its own checklist and its own contact at the operator.

Does the customer have to accept curtailment?

They choose a module. Modules without curtailment carry the smaller reduction; the module with network-oriented curtailment carries the larger one. The choice is theirs, and the operator's price sheet is the document that explains it.

Will the battery be switched off?

Network-oriented control limits the device's draw from the network — a limit on consumption, not a disconnection of the household supply. What that looks like in practice depends on the inverter configuration, which is why the setting is worth agreeing with the customer at handover rather than at commissioning.

Do existing installations have to be converted?

Existing controllable devices are handled on a transition path rather than immediately, and operators publish the deadlines that apply in their own network. Check the operator's current communication for the address instead of relying on a general rule.

Tell us the address's setup, not just the battery

We supply the battery, so the grid-side filings run through the operator and the inverter. What we can remove is the documentation uncertainty on our side: tell us whether the address is storage-only or storage plus a wallbox or heat pump, and which country it is in, and we will confirm in writing which battery documents — datasheet, communication details, and any listing the SKU holds — we can supply for that model before you quote.

Start with a specification and document enquiry, or browse the full product range.

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