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WP3 - Collectors (Deliverable 3.2)

The full report is confidential and will not be distributed to the public. However, a brief summary of the contents are given here.

This document presents the results of energetic performance and cost effectiveness analysis for selected breakthroughs in the field of solar collectors and primary circuits applicable in combined solar and heat pump systems developed in the frame of the MacSheep project. Investigated breakthroughs have been identified and selected as promising ones in the previous phase 1 of the project. The breakthroughs in solar collector technology analysed and presented with subvariants (sizing of collector area, quality level of collector breakthroughs, etc.) are:

  • hybrid photovoltaic-thermal liquid collectors (glazed, unglazed)
  • building integrated solar absorbers
  •  thickness insensitive spectrally selective paints
  • ventilated collectors with free convection
  • system integration of solar collector as a heat source for heat pumps
  • absorbers made from lower cost metals

These breakthroughs have been analysed by system simulations and cost calculations to reveal the potential to contribute to the target of the MacSheep project: 25 % less electric energy consumption at competitive costs compared to the benchmark system of the project. For each breakthrough, the description of the main idea, cost calculation, explanation of method for performance modelling and presentation of results are provided in individual chapters. Finally, results are discussed and summarized.

The investigated new design of glazed photovoltaic-thermal collectors with low emissivity photovoltaic absorbers has a potential to achieve electricity savings of the system at competitive costs. New system concepts with uncovered selective coated collectors combined with a brine source heat pump and small ice storage may improve system efficiency if a smart control strategy is chosen for switching between direct collector heat use and using collector heat as a source for the heat pump. Building integrated low cost absorbers and unglazed photovoltaic-thermal collectors do not help to reduce the electric energy demand of the system. Covered collectors with natural ventilation in combination with ice storages and brine source heat pumps are only attractive from an economic and energy savings point of view for special climatic conditions with high irradiation in winter (e.g. high alpine climates like Davos).

Overall, it can be concluded that some of the investigated breakthroughs may help significantly towards the overall goal of 25 % el. energy reduction of the MacSheep project, but they will have to be combined with other breakthroughs from other work packages in order to reach the final goal.

Based on these results, the MacSheep consortium has selected the following breakthroughs for further investigations and developments towards a prototype within phase 3 of the project:

  • glazed PVT collectors
  •  uncovered collectors with selective coating and lower cost metal


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