Page 309 - A Comprehensive Guide to Solar Energy Systems

Chapter 14 • Advanced Building Integrated Photovoltaic/Thermal Technologies 313

Table 14.2 Electric Performance of the BIPVT
Solar Water
Irradiance Flow Rate I SC /A V OC /V I MP /A V MP /V
−2
−1
(W m ) (mL min ) (ADC) (VDC) (ADC) (VDC) E / W FF (%) η pv (%) ηpv
Epv/W
pv
620 0 3.69 7.86 2.83 6.52 18.45 63.62 10.48
30 3.92 8.23 3.21 6.39 20.51 63.58 11.65
60 4.17 8.41 3.17 6.73 21.32 60.83 12.11
90 4.2 8.54 3.19 6.88 21.96 61.19 12.48
120 4.24 8.6 3.29 6.89 22.65 62.11 12.87
800 0 4.69 9.28 3.64 7.47 27.21 62.51 11.98
30 5.09 9.47 3.98 7.62 30.35 62.96 13.36
60 5.27 9.56 4.09 7.67 31.37 62.27 13.81
90 5.31 9.57 4.13 7.72 31.88 62.74 14.04
150 5.39 9.71 4.22 7.81 32.96 62.97 14.51
1000 0 5.68 10.02 4.52 8.01 36.22 63.61 12.76
30 6.17 10.31 4.91 8.24 40.46 63.60 14.25
60 6.26 10.42 5.09 8.32 42.35 64.92 14.92
90 6.38 10.57 5.18 8.43 43.67 64.75 15.38
150 6.62 10.83 5.24 8.57 44.91 62.64 15.82

versa. In this sense, a desired water flow rate can be adjusted based on a customer’s need
in terms of the harvested heat energy or the enhanced electricity generation efficiency.
Fig. 14.11 provides a general comparison of the relative increase in the outlet water tem-
perature compared to the inlet water temperature, thermal efficiency, and electric effi-
ciency provided by the present BIPVT panel at different water flow rates under different
irradiance intensities.
The comparison of the electric and thermal efficiencies of the present BIPVT roofing
panel with other typical PVTs or BIPVTs with water as the heat transfer fluid is presented in
Table 14.3. note that none of the studies in Table 14.3 took into account the energy needed
to operating pumps when calculating the efficiency levels. overall, the literature contains
many more performance evaluations of various PVT systems than that of BIPVT systems.
Thus, only some of them with similar features to the presented BIPVT panel were col-
lected in this comparison. Among the PVTs compared in the table, the PVT water collector
proposed by Fudholi et al. [36], which consists of a combined PV module and a spiral flow
absorber, exhibited the highest performance in the current literature. It was reported that
this absorber produced a PVT efficiency of 68.4%, a PV efficiency of 13.8%, and a thermal
−1
efficiency of 54.6% at a solar radiation level of 800 W m and mass flow rate of 0.041 kg s .
−2
one of the BIPVTs highlighted in the table was designed by Chow et al. [37] and in-
volved a centralized PV and hot water collector wall system. They too conducted ex-
perimental studies under different operating modes at different seasons. Their test re-
sults showed that the thermal efficiency and the corresponding electricity conversion
efficiency found by statistical analysis were 38.9% and 8.56%, respectively. Corbin and
Zhai [24] developed a prototype BIPVT roof collector and conducted an experimentally