Annex 38

Solar and Heat Pump Systems

A joint project with the IEA “Solar Heating and Cooling” Implementing Agreement (SHC) Task 44

The Task aims at optimising combinations of solar thermal energy and heat pump, primarily for one family houses.


Start date: January 2010

End date: December 2013


The objective of this Task is the assessment of performances and relevance of combined systems using solar thermal and heat pumps, to provide common definition of performances of such systems and to contribute to successful market penetration of these new systems.


Other objectives are needed to reach the main one where international collaboration is definitively needed to make it possible within a 4 years framework, mainly:

  • Defining performance figures of a combined solar and heat pump solution
  • Defining assessment and test methods of such systems
  • Analysing monitored data on such systems
  • Developping component models or integrating existing ones into a system model
  • Simulating various systems under common conditions
  • Providing guidelines of good practice to the market and stakeholder
  • Providing authorities with relevant information on the interest of such systems.
  • Staying close to the market and bringing independent information and knowledge to the actors on this market along the duration of the Task.

The scope of the Task considers solar thermal systems in combination with heat pumps, applied for the supply of domestic hot water and heating in family houses.

Project manager and participating countries

Finland, Germany, Switzerland (Operating Agent) and UK,

and from SHC: Austria, Belgium, Canada, Denmark, France, Germany, Italy, Spain, Sweden, Switzerland and the United States.


The Annex has been structured into the following tasks:

Task A Solutions and generic systems – Collection of information on monitored
projects and about 20 monitored installations, which will be evaluated. A map of
possible system configurations has been sketched and a new way to describe system
configurations has been proposed, so that different types of installations can be
more easily understood.

Task B Performance assessment – Discussions of a common seasonal performance
factor definition that would embrace both solar and heat pump performance. This
could be the basis for an international standard definition. Five technical laboratories
are committed within the Annex to define a common testing procedure for a system
combining solar collectors and a heat pump, typically in the range of 5-10 kW and
4-20 m2 of collectors for a single-family house.


Task C Modelling and simulation - Dealing with simulation tools and methods.
Initially, existing models for components of a system were recognised.
There is a need for validation of a solar collector model, including condensation and
ice formation on the absorber surface, often needed when solar collectors are used
as the heat exchanger with air for a heat pump. Transient heat pump models for
both air and ground sources are also needed. A reference case has been discussed,
and resulted in an extension with TRNSYS simulations and comparisons of the welldocumented
case of SHC Task 32.


Task D Dissemination and market support – Preparation of the newsletters to be
issued every year, the final handbook of the Annex, the website and the Annex logo.

IEA Heat Pump Centre c/o SP Technical Research Institute of Sweden E-mail: