A new solar dryer has successfully developed that can be operated in two modes of ventilation which are continuous and intermittent. This paper aims to analyse and compare the efficiency of the new solar dryer with the existing dryer. Without load experiment shows that the temperature of the new solar dryer with intermittent mode can increase up to 60oC compare to 50oC and 40oC for the new solar dryer with continuous mode and the current dryer respectively. Furthermore, the intermittent mode shows a saving of 60% on the electrical energy usage compared to continuous mode. The average solar collector efficiency for continuous mode was 0.47 whereas for intermittent mode the efficiency was between 0.1 and 0.4 in no ventilation period and within 0.6 to 0.9 with force ventilation. The drying experiment of Sericite mica shows that the moisture extraction rate (MER) of the current dryer, new solar dryer with continuous and intermittent are 1.46, 1.98 and 3.07 kg/day respectively.

Keywords:  Intermittent ventilation; moisture extraction rate (MER); sericite mica; solar dryer; temperature

Crystalline silicon (c-Si) wafer-based solar cells have been dominating the current photovoltaic industries. However, prevalent manufacturing practices are based on environmentally-harmful chemicals and expensive methodologies. This paper reports on the development of inexpensive, environmentally-benign phosphoric acidbased
emitter formation methods as an alternative to conventional highly toxic and poisonous POCl3 gas sourcebased chemistry. Two emitter formation approaches at temperatures in 850-925 ℃ range have been investigated. The first approach is referred to as the doctor blade (DB) technique, where the flat Si wafer surface is uniformly
coated by phosphoric acid (H3PO4) via a moving blade. A small gap between the blade and wafer is maintained in order to form a thin uniform film on the wafer. The second method is referred to as the extension of the blade method (EDB), where an un-doped wafer is placed proximately to the deposited H3PO4 wafer. During the high
temperature drive-in process, phosphorous emitter was formed on the un-doped wafer surface through evaporation and deposition of phosphorus atoms from H3PO4 coated wafer. All diffusion processes were carried out on 180 μm thick, planar boron-doped Si wafers in a conventional quartz tube furnace. The variation of sheet resistances over a broad range from ~20-180 Ω/sq were consistent with temperature dependence. Highest diffusion uniformity was observed for 10 % H3PO4 solution. Diffusion process simulations based on DifCad software were in good agreement with experimental data. The work reported here illustrates that an environmentally-benign approach in emitter formation based on H3PO4 is feasible for manufacturing solar cells.

Keywords: SEfficiency; emitter junction; phosphoric acid; sheet resistance; solar cells

In this work, a detailed information about physical properties of Cu2ZnSnS4 stannite phase by first principles calculation has been presented. Using density functional theory based on the generalized gradient approximation GGA, the structural properties such as lattice parameters and bulk modulus has been determined. In addition, structure electronic and partial density of state to characterize the electronic properties was also calculated. For the optical properties investigation, the absorption coefficient and the efficiency of energy conversion has been calculated. Finally, we have investigated on thermoelectric properties such as electrical conductivity, Seebeck coefficient, thermal conductivity and figure of merit to evaluate the potential of this material in different applications. From our results presented herein, we conclude that this material can be considered potential multifunctional material for thermoelectric and photovoltaic applications.

Keywords : Cu2ZnSnS4; first principles study; material modeling, photovoltaic; thermoelectric

Photovoltaic-thermal (PVT) collectors were developed by combination of photovoltaic (PV) panel and thermal collector. The combination of technologies in one system has the potential to reduce cost of materials, required space and also improves performance of collectors. The PVT collectors will produce electrical and thermal energy simultaneously. PV technology converts solar radiation into electricity while thermal collector will be converting solar energy to thermal energy. The main components of PVT collectors are PV panel, absorber plate, heat transfer fluid and insulator. Based on previous studies, PVT collectors were developed by using air, water and nanofluid as a heat transfer medium. The function of heat transfer process is to improve PV panel efficiency by removing excessive heat from module and at the same time generating thermal energy. In addition, the parameters that affecting PVT’s performances are including; mass flow rate of the fluid, area of collector, solar radiation and PV cell materials used. The overall performances of PVT collectors are depending on the electrical and thermal energy efficiencies. Therefore, the main objectives of this paper are to analyze energy and exergy efficiencies of PVT collector with different designs and types of working fluid. The performances were studied using concept of energy balance and exergy entropy analysis. Result has shown that energy and exergy efficiency are in the range of 40-75 % and 5-25 %, respectively.

Keywords: Efficiency; electrical energy; photovoltaic thermal (PVT); thermal energy; exergy

Recent innovations in high efficiency photovoltaic thermal (PV/T) collectors have made them most suitable renewable energy systems to be integrated in green buildings or utilized in industrial processes. This is attributed to the ability to produce electricity and thermal energy at once. The development in PV/T collectors have reached a new height with the implementation of nanofluids as cooling fluids. Another method that is gaining attraction is the use of Phase Change Material (PCM) to control the temperature of PV panels to maintain its open circuit voltage. This paper aims to review and determine the influence of nanofluids and phase change material on the performance of PV/T collectors in different system configurations (e.g. buildings, both industrial and residential). A comparison between the two, accompanied by an introduction of innovative work in this field is presented as well. The influence of nanofluids and phase change material is immense; from raising the thermal efficiency to
raising the operating electrical efficiency and reduce overall payback period of the system. This signifies the importance of performing critical review to establish a clearer understanding of suitable configuration of nanofluid and PCM based PV/T collectors.

Keywords: Phase Change Material (PCM); nanofluids; PV/T; pay-back period; efficiency

In a mosque environment, occupants are temporarily in the situation of various dress and congregate activities which desire comfortable environment. Inappropriate thermal comfort condition in a mosque leads the distraction in fulfilling the religious practice and also causing emotional influence. The proper setting of thermal comfort
parameters is important to provide a suitable environment for the mosque occupants. Proper investigations of thermal comfort may help to optimize the usage of the cooling systems such as air conditioning system. The objective of this paper is to investigate the thermal comfort performance of large-scale retrofitted air-conditioned mosques with intermittent operation in Penang, Malaysia. According to the survey, the mosques in this region can be categorized into five groups (G1 –G5) according to floor area (131.55 m2 to 2,920 m2). A case study is conducted on a large scale mosque with a floor area of 2,920 m2 that is equipped with a centralized airconditioning system. Result shows that the system produces an indoor thermal environment that within the range recommended by ASHRAE Standard 55. Most of the predicted thermal sensation under predicted mean vote (PMV) indices is achieved and within the comfort zone range (-0.5, +0.5). Some thermal strategies need to be applied especially on air conditioning system, operation configuration, handling procedure, zoning section as well as technical knowledge among mosque officials. Hence, the energy consumption of the mosque can be reduced while maintaining thermal comfort level of occupants.

Keywords: Air conditioning; comfort; mosque; thermal environment

In this study, a new theoretical approach (new mathematical model) encompasses the heat transfer and energy balance is proposed to determine the performance of the photovoltaic thermal (PVT) – thermoelectric (TE) air collector (PVT-TE) hybrid system. The hybrid system consists of PV panel and TE modules that can improve the energy efficiency of the system. Theoretical and experimental studies were studied using energy analysis to predict the output temperature (To) and PV temperature (Tp). To evaluate system performance, a theoretical model is developed using the energy balance analysis of this hybrid system. The matrix inverse method is used to complete the theoretical model. Effect of mass flow rate and radiation intensity is also being investigated. Experimental studies were carried out at the air flow rate of 0.02 kg/s, 0.04 kg/s and 0.07 kg/s, and radiation intensities are in the range of 342-922 W/m2. The results of the experimental and theoretical studies show that the percentage of errors between the theory and the experimental value of To and Tp are 1.14% and 1.75% respectively.

Keywords: Energy analysis; electrical; solar energy; thermoelectric thermal

Pulsed laser sources are attractive on account of their spatial and temporal controllability at room temperature. Pulsed lasers, in visible (VIS) (300 – 515 nm) and infrared (IR) (~ 900 – 1064 nm) spectral ranges, with pulse widths in micro to femtoseconds range, are used in a wide range of applications including doping, etching, texturing and deposition. In this study, an Nd-YAG dicing laser operating at 1064 nm wavelength with 200 nanosecond pulse duration has been employed to form silver ohmic contacts to an n-type emitter on a p-type silicon substrate. The laser beam was used to anneal screen-printed Ag polymer paste over a broad (~ 7 to 500 mJ/cm2) range of laser fluences. Computer numerical control software allowed fabrication of geometrical patterns with controllable diameters in 50-150-μm range. Contact resistance measurements were performed using the transmission line method (TLM). Contact resistivity exhibited fast decay from very large values to relatively constant as a function of laser fluence. This variation was attributed to laser energy below the threshold energy which no alloyed Ag/Si contact could be formed. The lowest contact resistivity at 200 mΩ.cm2 was measured at 35 mJ/cm2. This value was two orders of magnitude higher than the lowest value for thermally annealed contacts. For the laser parameters investigated here, optimum laser fluences were in 0.2-0.6 J/cm2 range. It may be possible to attain lower resistivity values trough post-laser annealing.

Keywords: Laser-fired contacts; metallization; pulsed laser; silicon solar cells; front contact

In this investigation, optimization of iodide/triiodide (I¯/I3¯) ratios on palm-based polyurethane (PU) polymer electrolyte’s composition for solid-state dye sensitized solar cell (DSSC) application is explored. Polyurethane polymer electrolyte is synthesized under nitrogen gas atmosphere by pre-polymerization reactions between palm kernel oil monoester-OH (PKO-p) and methylene diphenyl diisocyanate (MDI) at different LiI/I2 mole ratios. The effects of I¯/I3¯ mole ratios optimization on photovoltaic characteristics (short circuit current density, open circuit voltage, fill factor and power conversion efficiency), photo-response behavior (internal quantum efficiency) and internal charge transport properties (charge transport and recombination resistance, and chemical capacitances) of solid-state DSSC is examined by light-current-voltage (LIV), incident photon-tocurrent efficiency (IPCE) and electrochemical impedances spectroscopy (EIS) measurements. The currentvoltage characteristic of FTO/TiO2-dye/PU-LiI-I2/Pt at LiI/I2 1:0.125 mole ratio demonstrated a photovoltaic response with a power conversion efficiency of 1.8 % under a standard AM 1.5G illumination with 42 % of internal quantum efficiency. The short circuit current density (Jsc) and open circuit voltage (Voc) are measured at 8.7 mA cm−2 and 0.68 V, respectively. These promising results could be a first step toward a new generation of low-cost and effective solid-state DSSC.

Keywords: Bio-based polyurethane; dye sensitized solar cell; iodide/triiodide; polymer electrolytes

World energy outlook in its latest 2017 edition by the International Energy Agency (IEA) reported that the global energy demand is rising slowly compared to the past, but still expected an expansion of 30% in between today and 2040. Since energy demand and world population are exponentially growing, thus world cannot just depend on the exhaustible conventional sources to meet the demand. Renewable energy resources are the best alternative for conventional resources in meeting the world’s increasing energy demand, mainly in electricity generation sector. Along with the expansion in the renewable energy technology, hybrid renewable energy system is configured in eliminating stand-alone drawbacks such as unpredictable power source, unreliable cost, and high initial and operational costs. This paper presents a study on a technique for hybrid renewable energy system design and sizing, and the feasibility of the system is determined using a hybrid optimisation of multiple energy resources pro (HOMER Pro) software. HOMER Pro software has been widely used in configuring an optimised system, considering all the equipment modelled and sized in an efficient technique and the output from HOMER Pro study is discussed.

Keywords: Hybrid renewable energy system; HOMER Pro; optimal design; optimal sizing