Electrical Characteristic Analysis of Photovoltaic Thermal With And Without ∇-Groove Absorber

Received Oct 7, 2019 Revised Dec 22, 2020 Accepted Jan 12, 2021 The photovoltaic thermal (PVT) system is an up-and-coming renewable energy technology that simultaneously produces thermal and electrical energy. The objective of this paper is to improve the electrical efficiency of the photovoltaic thermal system with and without ∇-groove absorber. This study is an experimental investigation under an indoor solar simulator at The National University of Malaysia. The electrical characteristic of the PVT system is characterized by the scheming current (A), voltage (V), power (W) curves. The solar intensity and mass flow rate affected the electrical characteristic. The increase of produced power and electrical efficiency is caused by increasing the solar intensity and mass flow rate. The comparison between ∇-groove absorber and without ∇-groove absorber shows that the use of ∇-absorber can increase electrical efficiency.


INTRODUCTION
Thermal and electrical energy can be harvest by solar energy. Many technology achievements occurred to connect the energy from the sun and practiced it in the application. The heat of the photovoltaic panel is utilized for the application of PVT technology. The elimination of heat from the PV panel is transferred by fluid (water or air); it is called the cooling process to improve electrical efficiency. The heat useful is converted to hot water or hot air for the current application. The main benefits of the PVT system are that its system can produce thermal and electrical simultaneously, for any application, such as for cooling, heating, and drying. For efficiency, a combination of photovoltaic panels and solar thermal is good for limited space.
For the cheap and practice, integration of the PVT system in the building is negligible variation, manufacture and material can be reduced significantly. PVT system is a hybrid technology between the photovoltaic cell and solar heater technology. The photovoltaic panel problem is overhead when the PV panel is treated under the sun, the PV panel temperature increases obviously. It becomes electrical efficiency decreased. To increase electrical efficiency, this overheat is removed by transitory a heat removing fluid by air or water under PV panel [1]- [9].
The electrical and thermal efficiency of PVT based-air was conducted by Hazami et al. [10]. Using energy study, electrical and thermal efficiency was 15% and 50% correspondingly. The theoretical and experimental approach of PVT performances was studied by Slimani et al. [11] for unintended solar dryers. The results of electrical, thermal and all performances of the PVT system were 10.5%, 70%, and 90%, respectively. Ameri and Glolampour [12] analyzed PVT with flat transpired collectors by theoretical and experimental investigation. With the energy equation, thermal and PVT efficiency was 69.9% and 55% respectively. In condition warm summer and cold winter region, Li et al. [13] have done analysis thermal and Azriyenni et al. [14] have done an experimental investigation of solar radiation effect with different Module slope angle. The different slope angle namely is 300, 400 and 500 respectively. The effect of weather conditions, likely sunny or cloudy, have been analyzed. The yield of the experimental presented the overhead condition achieved the voltage produced by the photovoltaic system. Ananth and Kumar [15] have simulated the solar PV inverter by A Matlab/ Simulink. The results show that the inverter is fewer voltage and current harmonic gratified. Razman et al. [16] have introduced the reverse triangular number of PV model and the operational point with PV emulator. The PV model analysis results by the PV model have been computed correctly. Sunita and Kdhir et al. [17] have designed the controlling of the photovoltaic integrated hybrid multilevel inverter. The offered model is tested by Matlab or Simulink as simulation tools.
An integrated collector between V-Absorber and plat plate absorbers as a collector in the PVT system is called ∇-Absorber. The use of V-Absorber to cooling of Photovoltaic panel based-on air improved the thermal performance [18]- [21]. In this study, the v-groove is changed by the ∇-Absorber. An integrated collector between V-Absorber and plat plate absorbers as a collector in the PVT system is called ∇-Absorber. Two materials will expend surface area contact of photovoltaic. Heat conductivity by using ∇-Absorber is expected to be higher than v-groove alone. The modification of v-groove to expand the performance is designed with ∇-groove. The purpose of this design is to improve heat conductivity. The surface's conductivity in contact is expected to increase the heat conductivity that touches the photovoltaic panels (PV). However, the use of ∇-groove is expected to contact all of the photovoltaic panel's backsides. Heat transfer can be expected to increasing the performance of the PVT system. This paper proposes the electrical characteristic with experimental indoor testing of photovoltaic thermal with and without ∇-Absorber.

RESEARCH METHOD
The material of this research is ∇-absorber which was produced from a bar of aluminum. There are 13 units of the bar. The width and length are 3.4 cm and 114 cm respectively. The vertex angle of ∇-absorber is 60 o . The ∇-absorber was positioned under a photovoltaic or PV panel. The photovoltaic panel was used by monocrystalline of 100 Watt. For the design and equation detailed and explained in reference [22]. The solar simulator is used to trying indoor with the experimental investigation. The simulator was made with 40 halogen lamps, and the intensity of the simulator measured by the voltage regulator. Before collecting data such as the temperature of the PVT system, the PVT system ensured until balance condition around 30 minutes.
Where the maximum power ratio is Pm, Open circuit voltage product is Voc and closed circuit current is Isc. The structures of the PVT system are described by subsequent I-V curved countryside of the curve. The curve variation is resulted by changing temperature (Tpv) and solar intensity (S) PVT system. The power maximum is calculated as = Where Pm is power maximum, Vm and Im are the maximum voltage and current of PVT system respectively. The electrical efficiency is calculated as [23][24][25][26][27][28] = Where S is the solar intensity and Ac is the surface of an area of the absorber.

RESULTS AND DISCUSSION
The electrical characteristic of PVT based-air with and without ∇-absorber has been conducted under the solar simulator. The consequence of solar intensity and mass flow rate variation of the PVT system with ∇absorber has been shown in Figures 3 and 4, as summarized in Table 1. Table 1 shows the electrical characteristic with voltage (Vsc) versus current (Isc) and power (Pm) at the solar intensity of 520 W/m 2 and 820 W/m 2 . The maximum current (Isc) of the PVT system with ∇-absorber is 1.60 Ampere with a mass flow rate of 0.0069 kg/s and the maximum voltage (Vsc) is 18.77 volts with a mass flow rate 0.0491 kg/s. Optimum electrical efficiency is 4.22% at the mass flow rate of 0.0069 kg/s. The decreased mass flow rate from 0.0491 kg/s to 0.0069 kg/s of PVT ∇-absorber increased the current (Isc), Power (Pm) and electrical efficiency.      [29] Segmented fins Electrical efficiency enhancement of 4% Zhao et al. [30] Small cell with a glass Electrical efficiency of 12.4% Selimefendigil et al. [31] Two fins thicknesses Power enhancement reached 7.26 Mojumder et al. [32] Unglazed PVTC and rectangular fins attached to thin flat sheet The maximum electrical efficiency is 14.03% Nishioka et al. [33] CPV and Fresnel lenses Electrical efficiency increased by 0.5% Dubey et al. [34] Glass to glass and glass to tedlar 0.66 % outcome different with and without channel Liu et al. [35] CPC with microencapsulated phase change slurry enhanced electrical efficiency 1.8% Lee et al. [36] Nanofluids PVT system The electrical efficiency of 12.80%. Present study ∇-absorber The electrical efficiency increased by 0.6% Table 3 shows the previous study of the PVT system to cooling the photovoltaic module. The variation design to absorber is fins, nanofluid, CPC, microencapsulated, glass, and others. The use of unglazed PVTC and rectangular fins attached to a thin flat sheet reaches the maximum electrical efficiency is 14.03%. The electrical efficiency of a PVT system with nanofluid is 12.80%. The enhancement of electrical efficiency with concentrator photovoltaic module (CPV) and CPC with microencapsulated of 0.5% and 1.8%, respectively, aligns with our outcome in this paper. The increase of the PVT system depends on the parameters of the PVT system. The parameters are solar intensity, mass flow rate, fluid, type of absorber, and photovoltaic module type.

CONCLUSION
Electrical characteristic analysis of the PVT system with and without ∇-absorber has been conducted under the solar simulator. The maximum current (Isc), Voltage (Vsc), Power (Pm) and electrical efficiency are 1.60 A, 18.77 V, 22.01 W, and 4.22% respectively in PVT system with ∇-absorber. The comparison of electrical characteristics between with ∇-absorber and without ∇-absorber shows that the use of the ∇-absorber is higher performance than without ∇-absorber.