VDE-AR-N 4105:2026: what Germany’s new low-voltage grid code means for inverter, storage and charger makers

#What has changed — and when

VDE-AR-N 4105 sets the technical rules for connecting and operating generating plants and storage on Germany’s low-voltage grid. The new edition, VDE-AR-N 4105:2026-03, was published on 26 February 2026 (VDE Verlag; DKE lists 1 March 2026, and grid operators count the transition from 27 February). It follows a public consultation of the 2024 draft that drew 810 comments.

The rule carries more weight than before: following Bundesnetzagentur decision BK6-23-037 it is a binding technical safety rule under § 49(2) EnWG, not just a recommendation.

Two transition periods run in parallel:

Plants commissioned with 2018 certificates during the transition do not need to be re-certified later.

#The changes that matter for manufacturers

Unit certificates are issued under certification scheme type 1a of ISO/IEC 17067, and since 1 February 2025 they must be registered in the national ZEREZ database: without a ZEREZ ID, grid operators do not approve the connection.

#The opportunities

Zero feed-in opens constrained grids. Where the local grid has no export capacity left, a certified PAV,E protection now allows large PV-plus-storage systems at zero or limited feed-in. Hybrid inverters and storage systems with an integrated, certified PAV,E protection save installers an extra device — a clear selling point.

Commercial systems up to 500 kW get a lighter path. Rooftop systems on warehouses, farms and apartment blocks between 135 and 500 kW can now be connected under the low-voltage rule with unit certificates, instead of the heavier medium-voltage process. That widens the market for commercial string inverters and storage.

Bidirectional charging gets a defined route. For the first time, V2G-capable chargers have a clear place in the rule. Manufacturers of DC bidirectional chargers can certify the charger alone and enter a market that German grid operators can now approve.

Early certificates win tenders. The first 2026 certificate was announced in March 2026 (a hybrid inverter certified by TÜV Rheinland, according to the manufacturer). Installers and distributors will increasingly ask for the new edition well before the 2028 deadline.

#The challenges

Firmware and re-testing. Q(U) as default, the wider frequency window, RoCoF ride-through and the new P(f) dynamics — including charge/discharge reversal for storage — mean firmware changes and a new test campaign for most product families.

A moving test standard. The test procedures sit in DIN VDE V 0124-100, whose revision started in September 2025. Certifying early means testing against procedures that may still change; planning a regression test is prudent.

AC bidirectional charging is not settled. How compliance is split between an AC charger and changing vehicles is, in the grid operators’ own words, not yet finally resolved.

One firmware, many countries. The rule names three standard parameter sets but does not force German-only software. Manufacturers need clean configuration management so that German, EN 50549 and other national settings stay traceable in one firmware.

Lab capacity before the deadline. With every supplier re-certifying before early 2028, test slots will be scarce in 2027.

#A practical timeline

1. Now: gap analysis of each product family against the 2026 edition; plan firmware changes.
2. 2026–2027: pre-tests of Q(U), P(f), frequency and RoCoF ride-through, NA protection and PAV,E protection.
3. When DIN VDE V 0124-100 is revised: final tests, unit certificate, ZEREZ registration.
4. By early 2028 at the latest: 2026 certificates in place for all products sold in Germany.

TSINGHU tests the grid-support functions of PV inverters, storage converters and bidirectional chargers in China and prepares the evidence an accredited certification body needs for the unit certificate — one test campaign that also covers EN 50549 and other European grid codes.