In Germany, the document that clears a home battery for grid connection is not the battery's safety certificate. Connection is assessed at the level of the generating and storage unit: the network operator wants the inverter's unit certificate (Einheitenzertifikat), evidence of the NA protection settings and a single-line diagram of the installation, filed before commissioning. The battery's own certificates answer a different question. Registration in the Marktstammdatenregister (MaStR) is a third step — and it belongs to the plant operator, not to you.

That is the whole shape of it. The rest of this article is the practical detail: what each filing is, who owns it, and where installers lose time.

Two filings, two different owners

Step Who owns it Typical timing
Connection application with the network operator (Netzbetreiber) The registered electrical contractor installing the system Before installation — allow lead time for the operator's response
Commissioning notification, with the unit certificate and protection settings The same contractor At commissioning
Registration in the MaStR The plant operator — your customer After commissioning

The first two are technical filings. The third is a registration duty that sits with whoever operates the unit, and it is the one that most often falls through the gap. Put it in your handover document, because your customer will assume you handled it.

The unit certificate belongs to the inverter, not the battery

This is the point installers lose the most time on. VDE-AR-N 4105, Technische Anschlussregeln — Erzeugungsanlagen am Niederspannungsnetz, sets the technical requirements for planning, erecting, connecting and operating generating units on the low-voltage network.

Its scope is not limited to generation. The VDE/DKE catalogue describes the rule as setting additional general minimum technical requirements for generating units and storage, supplementing VDE-AR-N 4100 on the connection and operation of customer installations.

The compliance evidence the operator asks for therefore describes the unit — the inverter, its protection interface, and how it behaves on the network. A battery's product-safety listing is a different layer of evidence and does not substitute for it. If you want the detail on that other layer, see what a UL 1973 listing actually covers.

What the operator will actually ask you for

Requirements differ between operators, and each one publishes its own document list. A typical list for a generation or storage unit — this example comes from a German distribution network operator — includes:

  • the completed connection application, using the VDE-AR-N 4105 forms (Anhang F)
  • a single-line diagram of the installation
  • the unit certificate (Einheitenzertifikat) or data sheet for the generating unit
  • proof of the NA protection / interface protection configuration
  • the installer's declaration, with the registered electrical contractor's details
  • the commissioning notification, including measured values

Two practical points. First, get the current checklist from the responsible operator before you promise a commissioning date — forms and portals change. Second, a certificate is only valid for the models it names: check that the model designation and firmware version on the unit certificate match what you are actually installing.

The simplified route, and who it is really for

The VDE-AR-N 4105 forms include a simplified connection process for smallest generating units, smallest storage, and combined DC-coupled generation-and-storage units with a total SAmax of 800 VA or less at the network operator. Further conditions apply — for example where the installation wants feed-in remuneration.

Do not read the 800 VA figure as "battery capacity". It limits the unit's apparent power at the connection point, and it is deliberately small. A domestic storage system sized for real backup duty will not reach the operator through this route.

The MaStR entry is your customer's obligation

The Marktstammdatenregister is the Bundesnetzagentur's central register for electricity generation and storage units. Registration is free and online, and the deadline runs from the commissioning date — check the current window on the portal itself rather than relying on second-hand figures, because the consequences of a late entry fall on the operator.

The practical consequence for installers is that this is a handover item, not a commissioning item. Give the customer the unit's key data — type, capacity, commissioning date, location, operator details — in a form they can copy straight into the register, and it takes them a few minutes.

Before you specify a unit for a German site

What to check Where it comes from Why it matters at filing
Unit certificate for the exact inverter model and firmware Inverter manufacturer This is the document the operator's file turns on
NA protection settings, documented Inverter configuration Must be set and evidenced, not merely available
Battery safety listing, where the SKU has one Battery supplier Separate layer; model designations must match
Battery datasheet and communication details Battery supplier Feeds the single-line diagram and the operator's file
Transport documents for the battery Battery supplier Not a grid document, but it gates delivery

If you are specifying storage with a hybrid inverter, our hybrid inverter range lists the Huawei SUN2000 and Deye SG-series models we integrate. For grid compliance on those units, the unit certificate comes from the inverter manufacturer, so ask for the version that covers your exact model and firmware. On the battery side, the Storage Wall series covers 2.56–14.34 kWh wall-mounted LiFePO4 modules, and the documents we can supply for a battery are confirmed per SKU.

Storage is usually added to a plant that already exists, and the AC- or DC-coupled decision is made earlier — it constrains what you end up filing. That trade-off is set out in adding a battery to an existing solar system, and the physical side is covered in our installation-day walkthrough.

Questions installers ask us

Does the battery need its own unit certificate?

No. The unit certificate describes the generating unit as it behaves on the network. In a hybrid system, that unit is the inverter. The battery is a component inside it.

Can I file the battery's UL 1973 or IEC 62619 report instead?

No. Those documents address the product safety of the battery. Other parties — an insurer, for instance — may ask for them, but they are not the network operator's grid-compliance document. Keep both sets in the project file, clearly separated.

Who registers the system in the MaStR?

The plant operator. Installers often do it as a courtesy, but the duty is the operator's. If you file on their behalf, get written authorisation first.

Does the simplified 800 VA process apply to a 10 kWh home battery?

Almost certainly not. The threshold applies to the unit's apparent power at the connection point, not to stored energy, and the conditions around it are narrow. Plan for the standard connection process.

Tell us the SKU and the market

We supply the battery, so the grid-compliance chain runs through the inverter rather than through us. What we can remove is the documentation uncertainty on our side: tell us the exact SKU and the country it is going into, and we will confirm in writing which battery documents 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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