Scope of the task
The scope of the Task are the technologies for production of cold/hot water or conditioned air by means of solar heat or solar electricity, i.e., the subject which is covered by the Task starts with the solar radiation reaching the collector or the PV modules and ends with the chilled/hot water and/or conditioned air transferred to the application. However, although the distribution system, the building and the interaction of both with the technical equipment are not the main topic of the Task this interaction will be considered where necessary.
The main objective of this Task is to assist a strong and sustainable market development of solar PV or new innovative thermal cooling systems. It is focusing on solar driven systems for both cooling (ambient and food conservation) and heating (ambient and domestic hot water).
Technologies
In principle, solar assisted cooling systems may be operated by (1) solar thermal collectors connected to thermally driven cooling devices, (2) solar-to-electric converters (photovoltaics) combined with compression chillers or by (3) solar to mechanical energy converters (e.g. solar collector driven Rankine machines) combined with compression chillers.
The two first categories of systems seem to be closest to mass market application, although in particular in the case of small to medium units, PV driven compression chillers are the most promising and close to market solar solution today.
Even if, in areas with existing electricity grids, the question of PV driven cooling and heating seems to be reduced to the question of grid connected PV for reduction of peak loads, which result from air conditioning, the reality is not simple. Increase of self-consumption of solar PV in these countries leads to an important question of the coupling between PV and heat pumps as well as energy storage. PV driven solar cooling systems will be therefore specifically studied in this task.
The scope of the technologies in this Task is:
- Photovoltaïc + air conditioning system. By air conditioning, it means compression air conditioning and heat pumps (if heating as well) but as well in a larger extend, food conservation
- Solar thermally driven innovative and compact cooling+heating systems.
Applications
The main application covered by the project is cooling of buildings. Until recently, it seemed that solar assisted cooling had best chances for market deployment in cases of large buildings with central air conditioning systems, because of the unique development of solar thermal cooling solutions. But, with the huge market increase for cooling equipment in the small residential and small commercial sector and the tremendous PV panels cost decrease, the situation has changed.
Here reliable and cost effective solutions are necessary in which the solar collection provides heat and/or electricity over the whole year, i.e. for heating in winter, for cooling in summer and for production of domestic hot water through the entire year.
So called pre-engineered systems are seen as a solution for this application range. Therefore this Task also focuses on packaged solutions which will be pre-engineered systems with small capacities for the following building types: single family houses, small multi-family buildings, offices, shops, commercial centres, factories, hotels
All of these buildings can be grid connected or off grid in case of PV cooling and heating.
The studied cooling and heating power range will be from 1 kWcooling/heating to several tens of kWcooling/heating.
As for the association between photovoltaic and reversible heat pumps or air conditioners can be made indirectly with the presence of an electric grid, the main scope of the present Task will be the direct coupling between solar and cold production machine. However, special configurations and control strategies will be considered for certain countries, in Central Europe especially, to allow a maximised use of PV power direct for heating/cooling even without direct coupling.