MULTI-FAMILY HOME & §13K ENWG

Utilize instead of curtail

Section 13k of the Energy Industry Act (EnWG) ("Redispatch instead of curtailment") aims to reduce the curtailment of renewable electricity generation during grid bottlenecks. To achieve this, registered additional consumers in designated relief regions can absorb allocated quantities of electricity.

For larger residential buildings with a central hot water storage tank, a controllable electric heat generator can convert this energy into heat at specifically targeted times. The current trial phase runs until September 30, 2026; the competitive target model will begin on October 1, 2026.

FOR LARGER RESIDENTIAL PROPERTIES

Who is this model of interest to?

  • 01

    Real estate industry

    For companies with larger residential buildings and centralized hot water heating, power-to-heat can be an additional component if the location, heat demand, and §13k framework conditions align.

  • 02

    Property management companies

    Existing properties can initially be checked for technical and economic feasibility. Whether and how the solution is integrated into the existing heating system depends on the specific property.

  • 03

    Owners of larger properties

    Particularly relevant are buildings with a central hot water storage tank, sufficient heat demand, and a technically suitable installation and connection option.

THIS IS HOW THE PRINCIPLE WORKS

From grid bottleneck to usable heat

  • 01

    Curtailment is forecasted

    If renewable energy generation is expected to be curtailed due to grid congestion, electricity volumes that can be utilized can be determined in the §13k procedure.

  • 02

    §13k provides the framework

    Registered additional loads or their aggregators in designated relief regions may participate, provided that the respective conditions for participation are met.

  • 03

    The immersion heater is controlled.

    A controllable electric heating solution can consume power in a targeted manner within the approved time slots and generate hot water.

  • 04

    Energy is stored as heat.

    The central hot water storage tank absorbs the generated heat. This allows electricity to be used over time and the heat to be provided in the building later on.

The technical solution in the building

PROJECT-SPECIFIC HEATING SOLUTION

The necessary heating output is derived from the hot water demand, storage volume, available connection capacity, and the intended operating model.

For higher-output solutions, the electrical connection must be permanently and professionally installed by a qualified specialist company. The control system must be able to deploy the electrical power in a targeted manner in accordance with the intended §13k operation.

The specific output and technical design that makes sense will be determined during the project review.

Technical Principles

THE BUSINESS CASE

Lowering hot water costs in apartment buildings

The model becomes economically attractive when allocated §13k electricity volumes can be used more cheaply than the heat they replace in the respective property. Starting October 1, 2026, allocation in the target model will take place via daily competitive tenders.

Actual economic viability depends, among other things, on heat demand, existing heat generation, usable energy volume, metering and connection concepts, and specific supply and market conditions.

  • HEATING COSTS

    Use electricity efficiently

    Electric water heating supplements the existing heat generation specifically during the time windows in which §13k electricity can actually be allocated and used in an economically viable manner.

  • STORAGE

    Decouple heat over time

    A central hot water storage tank makes it possible to convert electrical energy into heat during an available time window and provide it later for hot water demand.

  • OBJECT-ORIENTED

    Check economic viability

    Reliable savings can only be calculated on a per-property basis. The decisive factors are consumption, heat generation, system structure, metering concept, and the respective applicable supply and market conditions.

    Request initial consultation 

ADDITIONAL EFFECT

Effects on the building's energy balance must be assessed on a project-specific basis.

If a portion of the previously fossil-fuel-generated hot water heat is replaced by electric heat generation, the energy rating of a building may change.

Whether this results in a measurable improvement in the energy certificate or even a different efficiency class depends on the building, the calculation method, the initial state, and the specific supply. An improvement cannot, therefore, be guaranteed across the board.

HAMBURG

Hamburg is designated as relief region H1.

In the currently applicable Section 13k implementation concept for the pilot phase, Hamburg is designated as relief region H1. Additional loads in Hamburg are intended to help reduce network-related redispatch and curtailment requirements in other regions.

The pilot phase runs up to and including September 30, 2026. The competitive target model will launch on October 1, 2026. Whether a specific building can participate must be checked based on its location, technical design, and the respective applicable participation requirements.

CLEAR DIVISION OF ROLES

Who is taking on which part?

  • NOVOLTO

    Device & Control

    novolto provides the electric heating technology and the corresponding control system for the project.

    View immersion heater 

  • DECARBONIZE

    Supply & Market Processes

    decarbon1ze covers power-to-heat solutions, supply, measured value processing, and energy industry market processes, and publicly names novolto as a partner.

  • SPECIALIZED PARTNER

    On-site installation

    Permanent electrical connection and installation of a high-performance heating solution are carried out professionally by a qualified specialist company.

FROM OBJECT TO OPERATION

Prerequisites and procedure

  • 01

    Suitability check

    The location, relief region, hot water preparation, heat demand, and basic technical suitability are being checked.

  • 02

    On-site appointment

    Installation situation, storage, electrical connection options, and metering concept are evaluated on-site.

  • 03

    Installation

    The project-specific heating solution is professionally installed and – if necessary – hardwired.

  • 04

    Integration & Operation

    Following technical setup, integration into the intended metering, supply, and control model takes place.

Frequently Asked Questions

Multi-family home & Section 13k explained concisely

The most important questions before an initial consultation.

What is §13k EnWG? For which buildings is the model suitable? What happens outside of the §13k time windows? Does this improve the energy performance certificate? Who supplies the electricity – and who does the installation?
Request initial consultation

§13k EnWG ("Redispatch instead of curtailment") aims to reduce the curtailment of renewable electricity generation due to grid bottlenecks. Eligible participants are operators of registered additionally switchable loads in designated relief regions or aggregators of such systems. The pilot phase runs until September 30, 2026; the competitive target model will apply from October 1, 2026.

The focus is on larger residential properties with centralized hot water heating and sufficient heat demand. In addition, the location, technical integration, metering concept, and the respective applicable §13k participation conditions must be suitable.

The §13k heating solution only supplements existing hot water heating during the windows of time that are actually available or allocated. Outside of these times, the existing heat generation remains relevant for the supply.

Partial electric water heating can influence the energy rating. Whether the energy performance certificate or the efficiency class actually improves, however, must be calculated for the specific building and cannot be guaranteed as a general rule.

novolto provides the heating technology and controls for the project. decarbon1ze handles the power-to-heat supply and energy market processes. Installation and electrical connection are carried out by a qualified specialist company.

INITIAL CONSULTATION & SUITABILITY CHECK

Is your building suitable for the model?

Please send us the key details regarding your property and the existing hot water system. Together, we can assess whether further evaluation is worthwhile.

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