Hybrid Systems: Solar-Thermally Assisted Heat Pumps

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Joel Young
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1 Hybrid Systems: Solar-Thermally Assisted Heat Pumps Jörn Ruschenburg, Marek Miara, Sebastian Herkel Fraunhofer Institute for Solar Energy Systems ISE EHPA 3rd European Heat Pump Forum Brussels, 20 May

2 Outline Introduction and background Monitoring results Classification of solar-thermally assisted heat pump systems Simulation results Summary and outlook

Introduction and Background During the last years, an increasing number of systems using a combination of solar thermal energy and compression heat pumps has been developed.

3 Introduction and Background During the last years, an increasing number of systems using a combination of solar thermal energy and compression heat pumps has been developed. Developers / manufacturers originate either from the solar energy sector or from the heat pump sector. No systematic analysis of the different concepts has been carried out yet. No indicators for even-handed assessment have been developed yet.

4 Advantages of Solar + HP Combinations Solar companies Increased solar fraction for heating and domestic hot water Alternative to concepts using very large heat storages Overall solar fraction > 50 % Heat pump companies Increased annual COP (above 5) Direct use of solar energy for domestic hot water or space heating if collector temperature is sufficient No temperature decrease of the ground over many heating seasons

110 heat pumps in newly built residential buildings project partnership with 7 producers and

5 Monitoring Heat Pump Field Test HP in New Buildings assessment of the efficiency of new heat pumps in residential buildings measuring approx. 110 heat pumps in newly built residential buildings project partnership with 7 producers and two power supply utilities, funding by the German Federal Ministry for Economics and Technology radiant heating " combination" floor heating"

6 Monitoring Results Seasonal Performance Factor (SPF) of Ground-Source Heat Pumps

7 Monitoring Results Seasonal Performance Factor (SPF) of Air-Source Heat Pumps

8 Various System Concepts for Solar + HP

9 8 System Categories (without claim to be complete) Name Description One beside the other Active regeneration Big buffer storage Maximum integration Unglazed collector Solar heating system Ambient air heat pump Direct evaporating no interaction solar energy for ground heat source regeneration buffer storage as interface betwenn solar and HP; increased solar gains due to low temperature condenser integrated in buffer storage as back-up unglazed solar collector solely to increase the inlet temperature for the evaporator of the heat pump and for active regeneration hybrid type solar collector (radiation, ambient air as energy source); often water-ice as phase change storage Conventional solar collector and ambient air used as heat source of the HP Collector is used as solely source using the refrigerant directly

10 Solar + HP System Examples Type 1 One beside the other (typically offered by producers of heat pumps and/or solar collectors like Viessmann, Vaillant, Nibe, Bosch Thermotechnik, ) system components do not directly interact control systems usually work separately

Solar + HP System Examples Type 2 Active regeneration (as offered by IDM-Energiesysteme, Immosolar, Schüco, Roth Werke) solar energy used for active

11 Solar + HP System Examples Type 2 Active regeneration (as offered by IDM-Energiesysteme, Immosolar, Schüco, Roth Werke) solar energy used for active ground source regeneration system allows increasing of the solar gains and prevents stagnation (occurs usually at high irradiation and low heat demand in summer)

Solar + HP System Examples Type 6 Solar heating system (as offered by Consolar, Aquasol, terra sunenergy) the heat pump uses energy accumulated in the ice buffer storage

12 Solar + HP System Examples Type 6 Solar heating system (as offered by Consolar, Aquasol, terra sunenergy) the heat pump uses energy accumulated in the ice buffer storage (latent heat storage) as source the buffer storage is almost free of losses because of its low temperature level for back-up, either a ground source or a hybrid collector is necessary

Simulation Study on the Potential of Solar + HP Systems (SFH, 140 m² floor area, located in Passau, Germany) System I: Reference heat pump system without any solar assistance System II: Solar

13 Simulation Study on the Potential of Solar + HP Systems (SFH, 140 m² floor area, located in Passau, Germany) System I: Reference heat pump system without any solar assistance System II: Solar collector separated from heat pump System III: Additional low temperature water buffer as heat pump source Sources Collector (1. priority) Demands Domestic hot water Heat pump Collector (2. priority) Heat pump Collector (3. priority) Space heating Heat pump evaporator

14 Simulation Results Description Reference system: air/ water heat pump without solar assistance Heat pump and solar system (for heating and DHW) separated In addition, collector feeds low temperature water buffer that acts as heat pump source Solar % 56.6 % Fraction DHW SPF System kwh heating demand 2480 kwh DHW demand 296 kwh from collector for heating 1396 kwh from collector for DHW 1077 kwh from collector as HP source

Solar Heating and Cooling Programme Task 44 Systems Using Solar Thermal Energy in Combination with Heat Pumps Classification of solar + HP systems is incomplete Indicators for assessment of complex

15 Solar Heating and Cooling Programme Task 44 Systems Using Solar Thermal Energy in Combination with Heat Pumps Classification of solar + HP systems is incomplete Indicators for assessment of complex systems do not exist Motivation for Task 44 Subtask A: Solutions and generic systems Subtask B: Performance assessment Subtask C: Modeling and simulation Subtask D: Dissemination and market support

16 Summary and Outlook Increasing number of solar-thermally assisted heat pump indicates the potential of such combinations Identification and development of optimised technical solutions (regarding both costs and efficiency) by field tests and simulations Development and implementation of control strategies required Definition of performance indicators is under development in IEA SHC Task 44, linked to systematic scientific treatment

17 Thank you very much! Contact:

Overview of IEA HPT Annex 50

Overview of IEA HPT Annex 50 Marek Miara Fraunhofer Institute for Solar Energy Systems ISE Joint Workshop IEA HPT Annex 49/50 and IEA EBC Annex 67 Heat pumps for nzeb, retrofit and energy flexibility Rotterdam,