Germany VDE-AR-N 4105: low-voltage generation monitoring

A solar, battery or generator dashboard may show exactly what happens behind a German low-voltage connection. It does not show which technical rule the distribution system operator accepted, whether the protection scheme is certified or whether parallel operation has been commissioned.

VDE-AR-N 4105 covers connection design, plant behaviour, Netz- und Anlagenschutz (NA protection), billing metering, operation and evidence of electrical characteristics. A monitoring project must therefore begin with the approved connection concept. A local meter may explain plant behaviour, but it does not define which edition applies, approve an inverter, prove protection operation or authorise parallel operation.

Use the current edition, then confirm project applicability

VDE FNN lists VDE-AR-N 4105:2026-03 as in force and gives 27 February 2026 as its publication date. Its public summary says the edition introduced simplified requirements for very small generation and storage, further development of P_AV,E monitoring and zero export, extended system-support requirements, provisions for bidirectional chargers and revised connection forms.

The public VDE material does not provide one broad transition rule covering every plant already planned, ordered, commissioned or modified under VDE-AR-N 4105:2018-11. Do not infer that every existing plant must be rebuilt immediately, or that every unfinished project may continue under the old edition. Record the design date, application date, equipment certificates, connection offer and planned commissioning date, then ask the responsible DSO to confirm the applicable edition and transition treatment.

A specific public FAQ permits three ways to implement the Solarspitzengesetz 60% PV-module limit until 1 March 2028, including certified P_AV,E protection under the 2026 edition, certified P_AV,E monitoring under the 2018 edition, or a permanent inverter active-power reduction under the cited section. That is a provision for that function, not a general transition period for the whole rule.

Separate the rule from the law and the DSO conditions

VDE-AR-N 4105 is an application rule, not legislation. EnWG section 19 requires electricity network operators to publish technical connection conditions. It also provides the framework for national general technical minimum requirements and for clearly identified DSO-specific additions or choices.

EnWG section 49 requires energy installations to be built and operated with technical safety and states that compliance with recognised engineering practice is presumed when the VDE technical rules for electricity are followed. For renewable generation, EEG section 10 separately requires the connection and safety equipment to meet the DSO's necessary technical requirements and EnWG section 49.

For a real project, read together:

1. the current VDE-AR-N 4105 edition;
2. VDE-AR-N 4100 for the low-voltage customer installation;
3. the responsible DSO's published Technische Anschlussbedingungen (TAB) and stated settings;
4. the connection offer and project-specific correspondence; and
5. the applicable statutory registration, connection and metering duties.

A generic monitoring specification cannot override any of these documents.

Confirm that the plant is actually in scope

The public VDE Verlag scope summary says the 2026 rule applies to all generation plants and storage operated in parallel with the DSO network. This includes systems that do not export and extensions or changes to existing plants. A zero-export setting therefore does not by itself turn a grid-parallel inverter into an island system or remove the connection process.

The voltage level also matters. VDE-AR-N 4105 is the low-voltage rule. A project connected at medium voltage may instead fall under VDE-AR-N 4110 even when individual inverters or meters use low-voltage interfaces. Confirm the point of connection and the DSO's classification before selecting equipment or evidence.

Keep certified connection evidence intact

The freely published Annex F forms show the connection evidence expected by the process. The application form requests, where applicable, ZEREZ identifiers for unit certificates, the NA-protection certificate and optional power-flow-monitoring protection, plus a single-line diagram. Other forms cover plant data and commissioning.

VDE FNN's public FAQ states that the sum of maximum apparent powers of all inverters, ∑ S_Amax, determines whether central NA protection is required; when it exceeds 30 kVA, central NA protection is required. It also warns that a permanent software reduction used in that assessment must be declared, protected against unauthorised reversal and remain effective through software updates.

Treat these as formal evidence paths. Preserve the approved single-line diagram, certificate identifiers, protection settings, coupling-device design, test results, commissioning declarations and DSO acceptance. A dashboard screenshot, Modbus register read or cloud alarm is not a substitute.

Design owner monitoring as a separate layer

Owner monitoring can still be valuable. Place measurements at boundaries that answer operational questions:

Record timestamps, phase values, active and reactive power, sign convention, data quality, device status and communication gaps. Keep missing data missing; do not turn a lost connection into zero generation.

Where an export controller or P_AV,E function is part of the approved scheme, use only the certified architecture and settings accepted for that project. A separate EpiSensor meter may provide comparison and diagnostics, but it must not become a second writer competing for the inverter set point or claim the protection function.

Define commissioning and change control

Before parallel operation, reconcile the installed equipment against the approved documents. Capture certificate IDs, firmware or parameter set where required, protection settings, test records, meter identities and the signed commissioning documents. Keep the DSO's approval and any operating restrictions with the site record.

Apply the same discipline to later changes. Adding storage, replacing an inverter, changing maximum apparent power, changing export limitation or updating control firmware may affect the approved design. Ask the installer and DSO whether a new application, evidence update or recommissioning is required before making the change.

Where EpiSensor fits

EpiSensor can provide owner-side interval measurements, equipment status, alarms and approved integrations around PV, generators and storage. A Gateway running Edge can retain timestamped operational data on site and forward approved records to the owner's platform.

This layer does not certify an inverter or NA protection, perform the electrician's tests, issue a ZEREZ identifier, approve the single-line diagram, commission the grid connection, replace the billing meter or act as the DSO's mandated control channel. System Builder can help define operational measurement after the connection point, applicable rule, DSO requirements and certified protection design are fixed.