Sol2Pump - High efficient combination of solar thermal plants, photovoltaic and heat pumps

Targeting a high level of decentralised energy supply on basis of renewable energy, the project analysed the possible combinations of solar thermal energy, photovoltaic and heat pumps. The project aimed to maximise the domestic energy supply due to utilisation of the building as short term energy storage. In addition to that, several optimisation measures had been developed. The impact on the energy supply and demand will be economically assessed through life cycle costing. On this basis, the potential load transfer and the use of this kind of systems had been evaluated in combination with smart grids.

Short Description




Starting point/motivation

Combinations of heat pump systems and solar thermal units or photovoltaic systems (PV)
are installed in detached houses as well as in large-scale projects. Thus the possible
coverage of a heat pump's demand through photovoltaic is unanswered yet.
The main focus of the project was to determine the possible self coverage of heat pump
systems by photovoltaic, utilizing high resolution load- and generation- profiles.

Contents and objectives

It was the aim of the project to measure several systems accurately and to determine the
potential for the combination of solar thermal, photovoltaic and heat pump systems. The
building was utilized as a short-term heat storage in order to maximise the usage of
Photovoltaic-Energy for the operation of the heat pump.


A continuous load profile measurement of 4 buildings with air heat pumps was carried out - in combination with solar thermal plants and/or photovoltaic. Considering the economic as well as the technical facts, planning recommendations were derived. The potential for heat pumps for load management of the power grid in Austria was determined.


The central objective was to develop an algorithm for dimensioning a PV system in
combination with a heat pump. Furthermore the results were disseminated to interested
parties (designers, installers, operators, etc.) to publicise the project results. The results of
this project deliver facts and figures and specific organizational and technological measures
and provide recommendations regarding:

  1. Figure of the synergy of PV and heat pumps concerning self load covering of buildings
  2. Analysis of the combination with the building as a short-term heat storage
  3. Experience on the realistic annual coefficient of heat pumps
  4. Effects of various smaller optimization measures (hydraulic heating balance, runtime optimization of the heat pump, etc.)
  5. Summary of the results in the form of a planning recommendation

Prospects / Suggestions for future research

Some problems will be solved with the development and integration of batteries. The energy
management of the domestic power demand will be simplified. For hot water existing water
tanks already provide effective ways to store energy from solar thermal plants or PV and
heat pumps. However a self sufficient home through PV in winter will not be possible. Only
the ambitious expansion of wind power can solve this problem to provide electricity for
households and esp. to power heat pumps from renewable sources in winter.

Project Partners

Project management

AEE - Arbeitsgemeinschaft ERNEUERBARE ENERGIE NÖ-Wien
Daniel Reiterer M.A. Ing.

Project or cooperation partners

Contact Address

AEE - Arbeitsgemeinschaft ERNEUERBARE ENERGIE NÖ-Wien
Schönbrunnerstraße 253/10
A-1120 Wien
Tel.: +43 (1) 710 75 23 - 15
Fax: +43 (1) 710 75 23 - 18