The ‘Z-en house' is a zero-energy housing project being carried out by ROBERTRYAN Homes based in
North Ayrshire, Scotland. In this project, the application of a PV Thermal (PV/T) solar roof has been
reviewed and the PV heated ventilation air is intended to be circulated throughout the house with the
support of a mechanical ventilation with heat recovery (MVHR) system—i.e. PV/T MVHR. Accordingly,
using this Z-en house project, a feasibility study on hypothetical PV/T MVHR systems was conducted with
the aim to facilitate the builder’s design decisions, where the heat from PV modules should be used
optimally to supplement space heating, while the expected power generation can well be maintained
without being reduced drastically by the cumulative PV heat. The heat generating capacity of low efficient
PV cells (e.g. amorphous) and the high efficient counterparts (e.g. mono- or poly-crystalline) was analysed
using the energy and environment simulation tool EESLISM. The air flow assisted by the MVHR system
was assumed to be 300m3/h and drawn under either a 7% efficient PV roof with the module coverage of
57.14m2 or a 14% efficient PV roof of 28.57m2. In both scenarios, the roof was also assumed to be tiled at
30°. As a result, when the roof receives the high incoming solar radiation, say 367W/m2 at 13.00 on 30th
January in Scottish climatic contexts, and the ambient temperature is 5°C, the temperature of ventilation air
under the low efficient PV roof can increase to 20°C at the ridge, while the temperature under the
polycrystalline may reach up to 16°C when the nominal power output of both systems is set to be 4kW. Not
only does this study unveil the differences in the heat and power generation capacity of low and high
efficient solar PV roofs, but it catalogues the potential variations (i.e. mass customisation) in response to
the change of settings as to the MVHR air flow velocity and the PV power output, roof angle and area, so
that builders based in similar cool climates can choose from the collection.