The grid-supporting solar house with full thermal and electrical supply

Project aim

FlexEhome is a publicly funded joint research project (BMWI, FKZ: 03EGB0025) with the goal of designing, constructing and evaluating a single-family house that covers its energy demand for electricity and heat at any time of the year exclusively through renewable energies used in the building and can additionally offer grid services to the surrounding electricity distribution network.


The motivation for the project arises from the challenge of improving future power grid flexibility. Due to an increasing share of renewable energies, the power grid must be able to react more flexibly than before to volatile feed-in characteristics. As an example of this development on the distribution grid level, the energy supply of residential buildings can be taken. For decades, only purely “consumer” buildings existed at the distribution grid level (cf. Fig. 1, left), which met their energy needs by drawing power from the grid. Nowadays, more and more buildings have become so-called “prosumer” buildings (cf. Fig. 1, center) with grid-connected photovoltaic systems, which not only draw electricity from the grid but can also feed it into the distribution grid in an unregulated manner. If the feed-in power of these “prosumer” buildings exceeds the power demand in the distribution grid, e.g. at the time of the midday peak, grid bottlenecks occur. Nowadays, these are mainly compensated by reducing the maximum feed-in power of individual photovoltaic systems. However, this means that renewable electricity is lost unused, which can be interpreted as a lack of power grid flexibility. Within , a highly flexible and thus grid-supporting operation is aimed at through the intelligent temporal use of energy storage (cf. Fig. 1, right), and this at every second of the year.

Figure 1
Integrales Raumwärmeangebot von Picea gegenüber der typischen Nachfrage eines KfW 40 Hauses mit 145 m² Wohnfläche am Standort Berlin

The Team

To achieve the project goals, experts from research (Hermann Rietschel Institute and the Department of Energy Technology and Environmental Protection at TU Berlin) and practice (homepowersolutions, Transsolar, Alberthaus) have joined forces. Together, they cover the areas of highly accurate building simulation, intelligent control, hydrogen-based energy supply, holistic architecture and, last but not least, high-quality structural execution. Through this project team, the findings of the highly accurate simulation results will be used to build, measure and evaluate Germany’s first grid-connected single-family house with full electrical and thermal supply in Berlin



Mutual introduction of the partners Clarification of the two core objectives within FlexEhome Organizational

Overall project meeting no. 1/2021

Allocation of tasks for monitoring existing Picea systems to evaluate previous heating support Discussion on the creation and evaluation of load profile time series for electricity, space heating and domestic hot water demand Presentation of a first house design

Overall project meeting no. 2/2021

Agreement of a monitoring report on the Picea existing installations Determination of the hot water and electricity load profiles to be used in FlexEhome (VDI 4655 generated site- and year-specific) Decision that a comparison of the load profiles to be used with measurement of real data will be carried out…

Project progress