Heat pumps assist the grid – ViFlex pilot project by Viessmann Climate Solutions and transmission system operators successfully completed

Allendorf (Eder), Bayreuth, Stuttgart, Germany, April 9, 2026 – As a result of the energy transition in the heating sector, the flexibility potential offered by heat pumps is also becoming increasingly important for grid stability in the electricity sector. In the ViFlex pilot project, climate solutions manufacturer Viessmann Climate Solutions and transmission system operators TenneT Germany and TransnetBW have jointly demonstrated for the first time under real-world conditions that heat pumps in private households have the potential to be used as flexible consumers in redispatching. As a result, they have the potential to prevent grid bottlenecks.

Viessmann Climate Solutions is part of Carrier Global Corporation (NYSE: CARR), a global leader in intelligent climate and energy solutions.

For the pilot project, more than 100 Viessmann heat pumps from residential customers were integrated into the transmission system operators’ networks during actual heating operations. The necessary data exchange took place via the Equigy Crowd Balancing Platform, an initiative by European transmission system operators aimed at supporting the harmonized integration of small-scale and decentralized flexibility into system services markets across Europe. Viessmann Climate Solutions has adapted the control of the heat pumps so that electricity consumption is shifted over time, thereby avoiding, for example, the curtailment of excess wind and solar power. Intelligently networked and controlled heat pumps can thus make an effective contribution to better integrating renewable energies into the power grid and reducing the use of fossil fuel power plants. “With ViFlex, we are demonstrating that heat pumps in residential buildings can be controlled flexibly, fully automatically, and without any loss of comfort for our customers. This makes it even easier for numerous households to contribute to the energy transition while actively stabilizing the grids,” says Janosch Balke, Product Manager Energy Services at Viessmann Climate Solutions.

Interaction between heat pumps, aggregators, and transmission system operators

Over a period of nearly three years, the ViFlex project conducted the inaugural testing of how heat pumps can be technically integrated into transmission system operators’ congestion management systems during actual operation. To this end, the heat pumps of the households participating in the pilot project were aggregated into virtual pools for individual grid areas via the Viessmann Cloud, and a forecast of load profiles and flexibility potential was submitted to the transmission system operators via the Equigy Crowd Balancing Platform.

Activation of pooled flexibility resources by the transmission system operators was also routed through the Equigy Crowd Balancing platform and transmitted by Viessmann Climate Solutions as control commands to the individual heat pumps. The climate solutions manufacturer was responsible for forecasting, aggregating, and controlling the heat pumps, while the transmission system operators tested the technical processes and potential interfaces with the operational processes of congestion management.

The practical experience gained from this project shows that heat pumps can be reliably used for grid-friendly load shifting – without restricting the heat supply to households. Transmission system operators TenneT Germany and TransnetBW view the project positively and see advantages and opportunities in the fact that innovative consumers can already contribute to providing usable flexibility potential. “With the increasing electrification of the heating sector, flexible consumers are becoming more important. ViFlex demonstrates that flexibility from households works technically and can make a real contribution to grid stability in the future. The next step is clear: a reliable regulatory framework for a hybrid Redispatch 3.0.” – Dr. Oliver Strangfeld, Member of the Executive Board, TransnetBW.

Next step: Large-scale pilot testing for Redispatch 3.0 and further development of the market design

The pilot project has convincingly demonstrated the technical feasibility and benefits of grid-optimized control of household heat pumps. To ensure that their potential can be harnessed on a large scale for congestion management, it is necessary to further develop the existing regulatory framework from cost-based Redispatch 2.0 into a hybrid Redispatch 3.0 through a market-based approach for small-scale, decentralized flexibility. Such a framework would allow households to voluntarily and non-discriminatorily participate in congestion management using their heat pumps, home battery storage systems, or electric vehicles, thereby actively supporting grid stability. The project partners will continue to advocate for the regulatory consolidation of Redispatch 3.0 and have already initiated follow-up projects in this context, such as the DataFleX funding project.

About Viessmann Climate Solutions

Founded in 1917 as a heating technology manufacturer, today Viessmann Climate Solutions is a leading global provider of sustainable climate (heating, cooling, water and air quality) and renewable energy solutions. The integrated Viessmann Climate Solutions portfolio seamlessly connects products and systems via digital platforms and services, creating an individualized feel-good climate for users. Viessmann Climate Solutions is part of Carrier Global Corporation, global leader in intelligent climate and energy solutions. For more information, visit www.viessmann-climatesolutions.com

Press Contacts:

TenneT TSO
Mathias Fischer
mathias.fischer@tennet.eu

TransnetBW
Matthias Ruchser
presse@transnetbw.de

Viessmann Climate Solutions
Isabell Köhne
Isabell.Koehne@carrier.com