E x a m i n i n g C o s t – E f f e c t i v e n e s s o f P V / T M V H R S y s t e m s
621
Table 2: Annual Heat Generation Capacity of Ventilated PV/T Integrated Roof (Noguchi et al. 2011)
The results indicate that PV generates heat which makes the air running under the PV
panels 10-15˚C warmer than the outside temperature even during the Scottish winter.
Low efficient amorphous silicon PV generates more heat than high efficient PV of the
same nominal power output due to the necessarily larger area of amorphous PV roof
coverage as well as the less sensitivity to temperature rise as opposed to the
mono/polycrystalline counterparts. However, the simulation did not extend to the study of
the effect of the ventilated PV/T air velocity any more than 1m/s; thus, it may be worth
examining the extended scope so as to clarify the relationship between the increased air
flow and the PV/T heat collecting capacity under the Scottish climate condition in depth.
PV/T Roof Building Integration
For demonstration of the PV/T architectural integration, ‘C21e tiles’ developed by
Solarcentury were considered due to the ease of installation and the architectural
integration capacity (Solarcentury 2009). C21e tiles are one of the solar photovoltaic tiles
readily available in the UK market today and they can be fitted to standard wooden
battens using traditional roofing practice (Fig.12).
The gross length of the panel is 420mm and the width is 1220mm. The module efficiency
of this m
onocrystalline silicon PV
is estimated at 14.9 %. The Individual unit weighs 8 kg;
however, when the tiles are laid at gauges, the weight possibly becomes 19.7 kg/m
2
. It is
assumed that the efficiency of PV systems reduces by about 0.5 - 0.7% every year.
However, the product comes with a 10 year warranty and power output is guaranteed for
25 years from date of commissioning.
There is a synergy between MVHR and PV/T systems. PV generated electricity can
contribute to the operation of an MVHR system while the ventilator can help extract fresh
air heated by PV. The combination helps create healthy comfortable living environment
Amorphous Silicon PV Thermal Energy Production [kWh/year]
4kWp
7% Efficiency
57.14m
2
: 8m x 7.14m
8kWp
7% Efficiency
114.28m
2
: 8m x 14.28m
Roof Tilt
Air Flow
0.5m/s (432m
3
/h)
Air Flow
1m/s (864m
3
/h)
Air Flow
0.5m/s (432m
3
/h)
Air Flow
1m/s (864m
3
/h)
30˚
4,689
8,292
4,974
9,671
40˚
4,723
8,347
5,010
9,739
50˚
4,656
8,228
4,939
9,597
Polycrystalline Silicon PV Thermal Energy Production [kWh/year]
4kWp
14% Efficiency
28.57m
2
: 8m x 3.57m
8kWp
14% Efficiency
57.14m
2
: 8m x 7.14m
Roof Tilt
Air Flow
0.5m/s (432m
3
/h)
Air Flow
1m/s (864m
3
/h)
Air Flow
0.5m/s (432m
3
/h)
Air Flow
1m/s (864m
3
/h)
30˚
3,440
5,327
4,305
7,602
40˚
3,466
5,369
4,337
7,660
50˚
3,419
5,294
4,279
7,554
