Intelligent Storage Heaters: A Flexible Technology for Existing Buildings

January 24 2025

Although new buildings are mostly equipped with heat pumps, there are still simple storage heaters with an installed capacity of more than 20 GW in existing buildings. Intelligent storage heaters can actively support the energy transition by being integrated into the energy system as controllable consumers. On behalf of EGH, EnQS has built the EGH platform based on Azure components, which optimizes around 3000 storage heaters in the field. Considerable flexibility potential can be exploited, particularly in conjunction with dynamic electricity tariffs, smart metering systems and §14a EnWG.

In Germany, electric storage heaters with a total installed power of more than 20 gigawatts still account for a significant share of the installed power in the electricity grid. Many of these devices date back to a time when the base load in the German electricity grid was supplied by nuclear power plants. The so-called night storage heaters could be charged (heated) with cheap electricity at night and release the stored thermal energy throughout the day.

Fig. 1: Distribution of market locations of controllable consumers

 

Although the efficiency of storage heaters with “only” 100% (COP = 1) is clearly at a disadvantage compared to modern heat pumps or air conditioning units (COP = 3 to 5), a change in technology does not make economic sense in many existing buildings:

  • Storage heaters are often installed in buildings that were built in the 1950s to 1970s as part of social housing.
  • In these buildings, the installation of water heating circuits required for the central operation of a heat pump is very expensive.
  • Alternatives to central heating with heat pumps could be decentralized air-to-air heat pumps (so-called “split devices”) or single-room infrared heaters. However, these also need expensive installation work in most buildings and they cannot shift electricity consumption as they have no integrated energy storage.

Fig. 2: Intelligent storage heater with IoT module

 

For these buildings, state-of-the-art, intelligent storage heaters offer a sensible and practical solution and also provide further advantages:

  • Flexible charging windows enable flexible energy use by allowing the appliances to shift energy consumption dynamically to time windows with cheap electricity prices. Thus, modern storage heaters charge automatically when there is a surplus of wind or solar energy available in the grid.
  • More efficient insulation: New storage heaters minimize heat loss and keep the stored energy available for longer until it is needed.
  • Remote-controlled fans enable precise control of the room temperature and respond to predefined temperature profiles.
  • IoT integration: The devices can be seamlessly integrated into communication networks to reduce consumption, e.g. through weather forecasts, analyze data and optimize operation.
  • Remote fault analysis: Problems can be detected and fixed at an early stage, often before the user notices any loss of comfort.

 

From night storage heaters to storage heaters using renewable electricity

These advantages can lead to a significant improvement in the user experience: Residents benefit from more efficient loading of appliances based on weather forecasts and individual heating profiles. They can conveniently control their heating systems via apps and receive transparent information on consumption and savings potential. The technology can also be used to flexibly adapt the heating power requirement to the generation. In the context of so-called controllable consumption devices in accordance with §14a EnWG, there is enormous potential for flexibility in the electricity grid. Currently, 56% ripple control technology, 40% time switching and 1% remote control technology are used to control the installed storage heaters (the rest are not controlled). This technology needs to be replaced by intelligent metering systems (iMSys), which have been rolled out millions of times since 2025, and the charging windows for electric storage heaters need to be expanded.

 

Intelligent control through IoT technology

The technical solution is already in use. On behalf of an operator of intelligent storage heaters, EGH Electric Green Heating GmbH, the EnQS team has implemented the EGH platform and is now flexibly and intelligently controlling around 3,000 storage heaters distributed throughout Germany in the second heating season.

At the heart of this is a backend that enables the devices to be controlled and monitored. It is based on cloud services from Microsoft Azure. These not only offer interface diversity, scalability and reliability, but also allow the development of individual control and optimization algorithms. In addition, the intention was not to build a proprietary energy management system, but a system that essentially consists of standard Azure components.

Fig. 3: Simplified architecture of EGH platform

Die wichtigsten Azure-Komponenten der EGH Plattform sind:

  • Azure Data Explorer (ADX) for high-performance storage of extensive time series data
  • Azure Stream Analytics for filtering and triggering events
  • Azure Functions for event-based optimization and provision of APIs

The individual charging profiles are calculated in an optimization component implemented within the platform. Parameters for the optimization include the outdoor temperature forecast, the remaining state of charge (SOC) of the storage heater and the desired target temperature of the resident. In addition, there is an individual loading coefficient based on historical data on heat loss in the specific home. The charging profiles (time windows each with an individual target core temperature for the next 24 hours) are transmitted to the storage heaters via another backend.

 

Fig. 4: ADX Dashboard (Support Tools)

In addition, a dashboard has been implemented that enables extensive analyses to be carried out efficiently. For example, service staff can detect and fix bugs at an early stage by identifying anomalies based on historical measured values. Users receive recommendations on how they can further improve comfort – for example by adjusting the heating profiles or increasing the load. In addition, the implementation of the loading profiles is monitored so that service calls can be triggered automatically in the event of deviations.

The entire IoT system is already “§14a ready”. If a smart metering system is retrofitted in the building, measured values can be transmitted via iMSys and control signals from the market or the grid operator can be implemented.

 

Experience from 2 years of practical use

A radio technology based on 868 MHz was initially used to connect the Edge devices to a local hub. All data transmission now takes place directly via an LTE module that is integrated into every storage heater. This changeover has significantly improved data quality. In addition, an automatic adjustment of the heating coefficient was introduced in order to be able to react dynamically to different consumption profiles. Both measures have significantly increased user satisfaction. The introduction of a user-friendly end customer app is intended to further improve interaction options for the end user.

Abb. 5: Endcustomer-App

The responsible metering point operator has not yet installed smart metering systems in any of the buildings, meaning that charging is still enabled using conventional ripple control technology. By connecting to iMSys, further potential can be exploited, for example by integrating dynamic electricity tariffs and shifting charging to “surplus times”.

 

References

 


 

EGH Electric Green Heating GmbH

EGH’s mission is to enable housing companies and private owners to modernize their night storage heating systems in an economical and climate-friendly way. EGH emerged from a development project launched in 2019 by a market-leading heating service provider and a well-known manufacturer of electric storage heaters and has been operating independently on the market since the second quarter of 2024. The company is managed by Sven Tetzner, who has specialized in the installation and operation of electric heating systems since the early 1990s and is thus continuing a family tradition in the 4th generation. The innovative Green Heating storage heating system is available from specialist partners in the trade. EGH offers intelligent operation and Germany-wide service as an option. EGH also offers housing companies the modernization solution in the contracting model from a single source.

EnQS GmbH

EnQS has been supporting manufacturers of energy management and IoT systems since 2016. Originally founded as a spin-off of the FZI Research Center for Information Technology, the EnQS team draws on many years of experience in the software development of decentralized energy management systems. What was applied research 10 years ago is now innovative product development.

The service portfolio is now based on three pillars: testing, software development and technical consulting. EnQS stands at the interface between electrical engineering and computer science and combines these two disciplines. To test prototypes and products, EnQS operates the EnQS Testlab with PV systems, energy management systems, inverters, battery storage systems, charging stations for electric vehicles and much more. EnQS has also been supporting its customers for several years with the connection of energy management systems and intelligent measuring systems (iMSys).

Contacts

EGH Electric Green Heating GmbH
Sven Tetzner, CEO
Kurfürstendamm 30, 10719 Berlin
Tel: +49 30 20253373 | E-Mail: kontakt@greenheating.de | www.my-green-heating.de

EnQS GmbH
Dr.-Ing. Birger Becker, CEO
Weberstr. 9, 76133 Karlsruhe
Tel: +49 721 957941-0 | E-Mail: info@enqs.de | www.enqs.de

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