Performance Analysis and Parametric Studies of a Bi-fluid Type Photovoltaic/Thermal (PV/T) Solar Collector in Simultaneous Mode Under Tropical Climate Conditions

  • Hasila JarimiEmail author
  • Mohd Nazari Abu Bakar
  • Mahmod Othman
  • Mahadzir Din
Conference paper


Performance analysis of a photovoltaic/thermal solar collector with a bi-fluid configuration (air and water) was conducted under real sky conditions in the tropical climate of Perlis, Northern Peninsular Malaysia. In addition to the electricity generated, this type of collector has enabled three different modes of fluid operation: air mode, water mode and simultaneous (bi-fluid) mode. The third mode of fluid of operation is the primary focus in this chapter. This chapter highlights the performance of the collector outdoors, in terms of the experimental and two-dimensional theoretical analysis at steady state. For collector testing under real sky conditions, analyses of the collector for varying sets of mass flow rates under environmental conditions of an average wind speed of 3 m/s and average solar radiation of 700 W/m2 were conducted. To obtain suitable data, experiments were conducted for each of the mass flow rates on ten different days of testing. For the simultaneous mode, when air flow rate was fixed at 0.0262 kg/s, at a water mass flow rate that varied from 0.0017 to 0.010 kg/s, the electrical efficiency and total thermal efficiency ranged from 8.13 to 8.60 % and 44.36 to 47.45 % respectively. When the water flow rate was fixed at 0.0066 kg/s, at an air mass flow rate that varied from 0.0092 to 0.0753 kg/s, the efficiencies ranged from 8.10 to 8.56 % and 44.06 to 50.37 % respectively. Theoretical analysis was then conducted and compared with the experimental analysis by comparing the trend of the curves and using mean absolute percentage error (MAPE) analysis. The curves were found to be in good agreement, and the computed MAPE for the fluids’ output temperature was less than 2 %. Parametric studies were then conducted to investigate the performance of the collector with the change in air channel depth and performance with the change in collector length. The feasibility of incorporating two different types of working fluid into the same PV/T solar collector was demonstrated based on the thermal and electrical energy output of the collector under real sky conditions. Therefore, this research will serve as a starting point for further research into a bi-fluid type PV/T solar collector, both experimentally and theoretically.


Bi-fluid Photovoltaic thermal (PV/T) 2-D steady state Outdoor Parametric 



Collector aperture area’s subsegment, equal to area of PV module’s subsegment (m2)


Conversion power factor


Specific heat capacity of air


Specific heat capacity of water


Inner pipe diameter


Outer pipe diameter


A general subscript to denote a fluid


A friction factor in a fluid’s channel


Global radiation


Heat transfer coefficient (W/m2 K)

hcvbs f1

Convection heat transfer coefficient from back surface of Tedlar to air flow (W/m2 K)


Convection heat transfer coefficient from back surface of Tedlar to water flow (W/m2 K)

hcvfin f1

Convection heat transfer coefficient from surface of a fin to flowing air (W/m2 K)


Wind convection heat transfer coefficient (W/m2 K)


Generalised notation for heat transfer coefficient of linear equations derived from developed energy balance equations for a general heat transfer coefficient i (W/m2 K)


Radiation heat transfer coefficient between inner surfaces of collector (W/m2 K)


Radiation heat transfer coefficient from PV cells to sky (W/m2 K)


Thermal conductivity of fin (W/mK)


Thermal conductivity of air (W/mK)


Thermal conductivity of water (W/mK)


Thermal conductivity of photovoltaic cells (W/mK)


Length of fin (m)


Subsegment for each temperature node

\( {\overset{.}{m}}_{f1} \)

Air mass flow rate (kg/s)

\( {\overset{.}{m}}_{f2} \)

Water mass flow rate (kg/s)


Total number of fins

\( {\displaystyle \sum }{Q}_{\mathrm{th},\mathrm{inst}} \)

Total instantaneous thermal energy produced by solar collector (J)

\( {\displaystyle \sum }{Q}_{\mathrm{PVT},\mathrm{inst}} \)

Instantaneous primary energy saving (J)


Rate of heat flux (W/m2)

quf1, m

Rate of heat transfer per unit area for air nodes (W/m)

quf2, m

Rate of heat transfer per unit area for air nodes (W/m)


Reynolds number


Total rate of solar energy absorbed by solar cells of PV module


Total energy absorbed by Tedlar


Temperature (K)


Ambient temperature (K)

Tbp, m

Temperature nodes of surface of back plate (K)

Tbs, m

Temperature nodes of back surface of Tedlar (K)


Mean temperature of surface of back plate with fins (K)


Mean temperature of back surface of Tedlar (K)


Mean temperature of cell (K)

Tf1, m

Temperature nodes of air flow in channel (K)

Tf2, m

Temperature nodes of water flow in copper pipe (K)

Tfin, m

Mean temperature of fin at subsegment m (K)

TPV, m

Temperature nodes of PV cells (at centre of cells) (K)


Temperature at reference point


Sky temperature (K)


Mean inner wall temperature of copper pipe (K)

Ut, m

Overall top heat loss coefficient for subsegment m


Maximum velocity of air (m/s)


Wind speed (m/s)


Tube spacing (m)


Absorptance of PV cells


PV module packing factor


Temperature coefficient at reference temperature


Thickness of PV module


Thickness of Si-cells


Thickness of Tedlar layer


Thickness of ethylene-vinyl acetate (EVA) layer


Fin thickness


Area of subsegment of PV module


Distance between temperature nodes (\( \Delta x=1\kern0.5em \mathrm{cm} \))


Emissivity of sky


Emissivity of glass cover

γbsbp, m

Area correction factor for heat transfer from back surface of Tedlar to surface of back plate with fins

γbs f1, m

Area correction factor for heat transfer from back surface of Tedlar to flowing air

γbs f2, m

Area correction factor for heat transfer from back surface of Tedlar to flowing water

γfin f1, m

Area correction factor for heat transfer from fin surfaces to flowing air

γbp f1, m

Area correction factor for heat transfer from surface of back plate with fins to flowing air

γbpa, m

Area correction factor for heat transfer from surface of back plate with fins to ambient


Transmittance factor of front cover glass of PV module




Electrical efficiency of PV cell


Electrical efficiency


Electrical efficiency converted to equivalent thermal efficiency


Fin efficiency


Fin effectiveness


Electrical efficiency at reference temperature

ηth f1

Thermal efficiency of air

ηth f2

Thermal efficiency of water

\( {\displaystyle \sum }{\eta}_{\mathrm{th}} \)

Total thermal efficiency of solar collector

\( {\displaystyle \sum }{\eta}_{\mathrm{PVT}} \)

Primary energy savings or equivalent thermal efficiency

\( {\displaystyle \sum }{\eta}_{\mathrm{th},\mathrm{inst}} \)

Instantaneous total thermal efficiency of solar collector


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Authors and Affiliations

  • Hasila Jarimi
    • 1
    Email author
  • Mohd Nazari Abu Bakar
    • 1
  • Mahmod Othman
    • 1
  • Mahadzir Din
    • 1
  1. 1.Universiti Teknologi Mara PerlisPerlisMalaysia

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