Grid-tied string inverter. Photo: Wikimedia Commons
Smart meter (Intelligenter Zähler). Photo: Wikimedia Commons
The Erneuerbare-Energien-Gesetz (EEG)
The Erneuerbare-Energien-Gesetz (EEG) is the primary legislative instrument governing renewable electricity generation and grid integration in Germany. First enacted in 2000, the law has undergone major revisions, notably in 2012, 2017, 2021, and 2023, each adjusting the compensation rates, system size thresholds, and administrative requirements that apply to residential PV installations.
The EEG establishes a statutory right for operators of eligible renewable energy installations to connect to the public grid and to receive a defined payment for electricity fed into the grid. For residential rooftop systems, two compensation mechanisms are available depending on system capacity and the operator's preference.
Fixed Feed-In Tariff (Einspeisevergütung)
Smaller residential systems — up to specific capacity thresholds defined in the current EEG — are eligible for a fixed feed-in tariff (Einspeisevergütung) paid per kilowatt-hour of electricity exported to the grid. This rate is guaranteed for a period of 20 years from the commissioning date, providing planning certainty for the installation operator. The applicable tariff rate is set at the time of commissioning and does not change with subsequent amendments to the EEG.
The EEG includes a degression mechanism: the monthly feed-in tariff rates for new installations decrease incrementally. The magnitude of the degression is linked to the volume of new PV capacity installed nationally in each period; faster market growth triggers higher degression rates. Current tariff values are published quarterly by the Bundesnetzagentur and should be consulted directly, as rates change over time.
Direct Marketing (Direktvermarktung)
Larger residential and commercial systems exceeding the threshold for fixed tariff eligibility must participate in direct marketing, where the electricity is sold on the wholesale electricity market. Operators in direct marketing receive a market premium (Marktprämie) from the grid operator to make up the difference between the wholesale market price and a reference value defined by the EEG. In practice, most operators in direct marketing engage a direct marketing provider (Direktvermarktungsunternehmen) to handle the market transactions on their behalf.
Grid Connection Procedure
Connecting a residential PV system to the public low-voltage grid in Germany involves the local distribution network operator (Netzbetreiber or Verteilnetzbetreiber, VNB). The identity of the relevant network operator for a specific address can be determined through the Bundesnetzagentur's online tools or by contacting the local energy supplier.
Grid Connection Request
Before installation begins, a grid connection request (Netzanschlussbegehren or Inbetriebnahmeantrag) must be submitted to the network operator. This application includes technical details of the planned system: peak power in kilowatts-peak, inverter specifications, and the proposed connection point. The network operator has a statutory obligation to respond within a defined period and to confirm whether the local grid can accommodate the additional generation capacity.
For systems below the standard threshold (typically 30 kWp at low voltage), connection is generally straightforward and proceeds through a simplified notification procedure. Larger systems may require a grid compatibility assessment (Netzverträglichkeitsprüfung), which can extend the timeline.
Technical Standards: VDE-AR-N 4105
The technical requirements for generators connected to the low-voltage network are defined in VDE-AR-N 4105 (Generators connected to the low-voltage distribution network). This standard specifies the inverter's behaviour during grid disturbances, including requirements for voltage and frequency ride-through capability and mandatory anti-islanding protection. Anti-islanding ensures that the inverter disconnects automatically if the grid supply fails, preventing unintended energisation of the local network during outages, which would create safety hazards for line workers.
A grid-connected PV system requires a bidirectional electricity meter (Zweirichtungszähler) that records both electricity drawn from the grid (Bezug) and electricity exported to the grid (Einspeisung) separately. The network operator is responsible for installing and maintaining the meter. For systems above a defined capacity threshold, an intelligent measurement system (smart meter / Intelligentes Messsystem) with remote reading capability is mandatory under the Messstellenbetriebsgesetz (MsbG).
Timeline for Connection
Once the grid connection request has been approved and the system installed by a qualified electrician, a commissioning inspection takes place before the network operator activates the feed-in metering. The total elapsed time from application to grid connection typically ranges from four to twelve weeks, depending on the network operator's capacity and whether any grid reinforcement is required at the connection point.
Marktstammdatenregister (MaStR)
All grid-connected electricity generation and storage systems in Germany must be registered in the Marktstammdatenregister (MaStR), a publicly accessible database maintained by the Bundesnetzagentur. Registration is mandatory regardless of system size and must be completed within one calendar month of commissioning.
Registration Process
Registration is completed online through the MaStR portal at marktstammdatenregister.de. The process requires creating an account, registering the installation unit (Einheit), and providing technical details including the system's peak capacity, location, connection voltage level, and inverter specifications. The registration generates a unique MaStR number assigned to the installation, which is referenced in subsequent communications with the network operator and for EEG reporting purposes.
Consequences of Missing Registration
Failure to register within the required period or providing incorrect data can affect eligibility for feed-in tariff payments. The EEG specifies that the obligation to pay the feed-in tariff begins only once the installation is properly registered. Retroactive registration is possible but may result in delayed compensation.
Self-Consumption and Grid Parity
For residential installations, electricity generated by the PV system and consumed directly within the building (Eigenverbrauch or Selbstverbrauch) avoids the purchase of grid electricity at the retail price, which typically includes energy taxes, grid fees, and renewable energy surcharges. The economic benefit of self-consumption frequently exceeds the per-kWh value of the feed-in tariff, making self-consumption maximisation a priority in system design and operation.
Battery Storage
Stationary battery storage systems coupled with the PV array increase the share of generated electricity that can be consumed on-site by storing midday surplus for use in evening hours. Batteries for residential PV use lithium-ion chemistry almost exclusively. The interaction of a battery system with the feed-in tariff depends on how the system is connected and metered; systems that draw from the grid to charge the battery are treated differently from those that only store self-generated electricity. Current EEG provisions address this distinction, and the applicable rules should be reviewed in the context of the specific installation configuration.
Tenant Electricity (Mieterstrom)
A specific provision in the EEG covers scenarios where a landlord installs PV on a residential building and supplies electricity directly to tenants (Mieterstrom). Qualifying installations benefit from a Mieterstrom supplement paid on top of the avoided grid purchase. The provision applies subject to capacity limits and requires the building to meet certain criteria regarding the type of use.