There are key advantages in cost and performance to be gained by combining photovoltaic and solar thermal functions into the south facing facade of a building. This research proposal seeks to build on the experience gained with the Mataro library project (supported by the JOULE programme). In particular, the innovative introduction of dedicated solar air heaters into part of the facade and the use of forced ventilation will be explored, in view of the requirement for higher air temperatures. Ventilation can be directly powered from the photovoltaic array, thereby minimising wiring and providing a robust self-contained system. The way in which the facade can be utilised for building heating and cooling will be explored in the context of an integrated building design incorporating underground thermal storage. By using a partially transparent facade, natural daylighting can be provided through the south face of the building, without associated overheating.
It is intended that this research project will result in design guidelines for such buildings, and in particular a detailed design for an integrated solar building which would later be constructed as part of the planned new Engineering complex at Loughborough University, using the technology developed.
It is well known that photovoltaic modules perform more efficiently at low temperatures. For crystalline silicon modules, the efficiency falls by around 4 to 5 for each 10 degree C increase in temperature. For this reason some researchers have started to look at the cooling of PV facades, generally by allowing natural convection of air behind the solar panels. This has led to consideration of whether the heat generated could be usefully used to pre-heat the air supply to the building. Among the first demonstrations of this approach on a full size building is the public library in Mataro near Barcelona where an actively ventilated 53 kWp PV array is used to pre-heat air for space heating. Because the Mataro array has a transparency of 15%, light is also allowed directly into the interior of the building without producing glare or overheating of the space. Air temperatures from such a facade will always be limited due to the need maintain a low operating temperature for the PV modules, and due to their non-optimum thermal properties. This will significantly limit the space heating contribution that can be achieved with such a design. This project will examine the potential for space heating if dedicated solar thermal air heaters are incorporated into the facade. In order to achieve good heat transfer within the collectors, forced convection will almost certainly be required as stack effect/buoyancy driven flows rates are limited. The power supply for the necessary fans could be provided directly from part of the PV array, and this will also be investigated. This promising integration of solar air heaters into a PV/solar thermal facade has not so far been studied.
Funding SchemeCSC - Cost-sharing contracts
08110 La Vallensana