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• Dust and pollutants accumulated in the PVT system were investigated. • The dust accumulation and cleaning effects on PVT system performance were evaluated. • Comparisons with PV modules and thermal collectors are presented. • After 30 days of exposure to outdoor conditions, the percentage of energy generated per day was 61.17 %, 46.96 %, and 42.73 % for clean, polluted, and conventional systems, respectively. • After 60 days of exposure to outdoor conditions, the average daily energy generated was 60 %, 38.18 %, and 33.9 % for clean, polluted, and conventional systems, respectively. Dust causes losses in power generated by the PV modules as well as causes an increase in their temperatures. In this study, the photovoltaic/thermal (PVT) module dust heating effect was investigated using a spiral coil using for two PVT water cooling systems. One of the two systems was cleaned periodically (every-two weeks) and the second was left polluted with dust. The practical tests were conducted in Sohar – Oman outdoor conditions for two months (July and August 2021). The two systems performance was compared with a PV module left without cleaning. The dust accumulated on the studied systems caused a decrease in their average productivity. After 30 days, the clean PVT, polluted PVT, and conventional PV systems; yield was 61.17 %, 46.96 %, and 42.73 %, respectively. After 60 days, the average daily energy generated was 60.00 %, 38.18 %, and 33.90 % for clean, polluted, and conventional systems, respectively. Increasing the exposure period to external conditions caused an increase in the accumulated dust rate, resulting in a deterioration in the power output of both polluting PVT and conventional PV. In the periodic cleanliness of the PVT system, most of its performance was restored and its losses were limited. After 4 and 8 weeks, the yield losses for the conventional PV system were (9 % and 20 %), (2.5 %, 3.3 %) for the clean PVT system, and for the polluted PVT system they were (7.5 %, 17.7 %). [ABSTRACT FROM AUTHOR]

Iraq is characterized by hot and sunny weather with high radiation intensity. These conditions are suitable to produce photovoltaic electricity, on the one hand, but on the other hand are not suitable for photovoltaic modules whose efficiency decreases with increasing temperature. In this study, a photovoltaic module was practically cooled by two PV/T systems, one cooled by water and the other by nanofluid and nano-paraffin. Iraqi-produced paraffin was used in this study for its cheap price, and because its melting and freezing temperature (46 °C) is close to the operating range of photovoltaic modules. Nano-TiO2 was adopted as an additive to water and paraffin. The study results showed an obvious enhancement of the thermal conductivity of both water and paraffin, by up to 126.6% and 170%, respectively, after adding a 2% mass fraction of nano-TiO2. The practical experiments were carried out outdoors in the city of Baghdad, Iraq. A fluid mass flow rate of 0.15 kg/s was selected for practical reasons, since at this rate the system operates without vibration. The PV panel's temperature, in the PV/T system (nano-fluid and nano-paraffin), decreased by an average of 19 °C when the tested systems operated during the peak period (12 PM to 3 PM). The decrease in temperatures of the PV module caused a clear improvement in its electrical efficiency, as it was 106.5% and 57.7% higher than the PV module (standalone) and water-cooled PV system, respectively. The thermal efficiency of this system was 43.7% higher than the case of the water-cooled PV/T system. The proposed system (nano-fluid and nano-paraffin) provides a greater possibility of controlling the heat capacity and increasing both efficiencies (electrical and thermal), when compared to a standalone PV module, in harsh Iraqi weather. [ABSTRACT FROM AUTHOR]

Both electrical and thermal efficiencies combine in determining and evaluating the performance of a PV/T collector. In this study, two PV/T systems consisting of poly and monocrystalline PV panels were used, which are connected from the bottom by a heat exchanger consisting of a spiral tube through which a nanofluid circulates. In this study, a base fluid, water, and ethylene glycol were used, and iron oxide nanoparticles (nano-Fe2O3) were used as an additive. The mixing was carried out according to the highest specifications adopted by the researchers, and the thermophysical properties of the fluid were carefully examined. The prepared nanofluid properties showed a limited effect of the nanoparticles on the density and viscosity of the resulting fluid. As for the thermal conductivity, it increased by increasing the mass fraction added to reach 140% for the case of adding 2% of nano-Fe2O3. The results of the zeta voltage test showed that the supplied suspensions had high stability. When a mass fraction of 0.5% nano-Fe2O3 was added the zeta potential was 68 mV, while for the case of 2%, it reached 49 mV. Performance tests showed a significant increase in the efficiencies with increased mass flow rate. It was found when analyzing the performance of the two systems for nanofluid flow rates from 0.08 to 0.17 kg/s that there are slight differences between the monocrystalline, and polycrystalline systems operating in the spiral type of exchanger. As for the case of using monocrystalline PV the electrical, thermal, and total PV/T efficiencies with 2% added Fe2O3 ranged between 10% to 13.3%, 43–59%, and 59 to 72%, respectively, compared to a standalone PV system. In the case of using polycrystalline PV, the electrical, thermal, and total PV/T efficiencies ranged from 11% to 13.75%, 40.3% to 63%, and 55.5% to 77.65%, respectively, compared to the standalone PV system. It was found that the PV/T electrical exergy was between 45, and 64 W with thermal exergy ranged from 40 to 166 W, and total exergy from 85 to 280 W, in the case of using a monocrystalline panel. In the case of using polycrystalline, the PV/T electrical, thermal, and total exergy were between 45 and 66 W, 42–172 W, and 85–238 W, respectively. The results showed that both types of PV panels can be used in the harsh weather conditions of the city of Baghdad with acceptable, and efficient productivity. [ABSTRACT FROM AUTHOR]

Solar energy and photovoltaic (PV) systems became an essential part of the global energy profile. The PV systems are designed using different configurations such as standalone, grid-connected, and tracking. However, PV systems could be added to other renewable energy systems or nonrenewable energy systems such as wind turbines and diesel generators, respectively. In this context, designers, researchers, and engineers working to find the optimum design fitting the electrical load in terms of technical, economic, environmental, and social aspects. Many software, models, and algorithms were invented and proposed to help to find the optimum PV sizing and design. In this paper, a comprehensive review was conducted to describe, evaluate, and compare most of the software (36 software were considered), models, and algorithms used to design PV systems in the past eight decades. It is found that PV system design optimization tools developed with time and needs. Different classifications are used for design software, sometimes as classical and artificial or single and hybrid algorithms. However, hybrid algorithms became the most used algorithm due to their flexibility and ability to deal with complex problems. Also, comparison and critical review are presented, and a case study is given in this paper. It is found that REPS.OM software results are closer to the case study experimental results compared with HOMER software with less than 7% variation between the two software. The review presented in this paper provides useful information to identify PV system design software suitable for the user application. [ABSTRACT FROM AUTHOR]

• Evaluation of ageing and performance of grid-connected PV. • A seven years measured data used to evaluate the PV performance. • Power losses, degradation of energy, yield, and efficiencies was calculated. • Ageing impact compared with studies in literature. In this study, the aging measurements of a 1.4 kW grid-connected photovoltaic system were analyzed. The system is located at the Solar Energy Laboratory at the College of Engineering, Sohar University, Sohar, Oman. The system variables were monitored and measured for a period of seven years, starting from 1 October 2012 until 30 September 2019, during which the electricity produced to the network was fed. Weather data metrics measurements showed solar irradiation values, ambient temperature, and the PV module temperature were measured for seven years. The performance criteria for the different PV system, which included (the PV module and system efficiency), performance ratio, and capacity factor were measured in addition to the different losses and system productivity. The results showed that the system is exposed to aging, although the amount of its impact is relatively small, as the study was conducted for a seven-year-old, while the effect of aging is more at longer ages. The measured aging caused the system efficiency to decrease by 6.3% and the production rate to 5.88% while the mean daily array capture loss and system loss were 6.95% and 6.13%, respectively, and the capacity factor decreased by 4.91%. Measurements during the seven years showed that the rate of degradation is greater during the summer than the rest of the seasons due to the high radiation intensity which causes high temperatures of the PV units in addition to the high dust density during this season. The results showed that the use of GCPV systems in the Sohar region is very successful in terms of the limited aging of the system and its long-term viability with appropriate efficiency. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights: • A mathematical model for nanofluid and nano-PCM PVT is presented. • Discretization of parameters and equation was made. • An experiment has been conducted to validate the simulation results. • The nano-PCM PVT's glass and solar cell maximum temperatures recorded were 41.2°, 39.92 °C, respectively. • The nano-PCM and nanofluid maximum temperature achieved were 38.8° and 36.5 °C, respectively. Abstract The photovoltaic/thermal (PVT) system is developed to combine the two separate systems to reduce the located area and cost, improve the efficiency and save lots of materials. However, different PVT designs and configurations had been proposed with air, water, nanofluid, phase change materials (PCM) and mix of these cooling methods. In this paper, a mathematical model was proposed for the new nanofluid/nano-PCM PVT system. Experiments had been conducted to validate the mathematical model results. The comparison confirmed the ability of the proposed mathematical model to satisfactory simulate and match the experimental results. The experimental and mathematical model results show that electrical and thermal efficiencies are 13.7%, 13.2% and 72%, 71.3% respectively. However, it is found that the maximum temperature registered in glass, PV cell, wax, and nanofluid are 41.2, 39.92, 38.8 and 36.5, respectively. The proposed mathematical model accuracy compared and validated with experiment results and shows a good consistent and agreement. [ABSTRACT FROM AUTHOR]

The reduction in efficiency of photovoltaic (PV) units due to increases in cell temperature occurs when a small part of the absorbed solar radiation is converted into electricity and the remaining part is lost as heat. Recently, the addition of a range of nanomaterials with high thermal conductivity to the cooling fluid in PV/T systems has been the subject of much research. In this study, three nanomaterials were added to water as a base fluid with several volume fractions to determine the best concentration and nanoparticle for this application. The PV/T system was setup in an indoor laboratory. Knowing which material has a better effect on the PV unit in particular, and the PV/T unit in general, is important for deciding which nanomaterial is more suitable for the system. The results reveal that nanofluid gives higher thermal conductivity with very little increase in the fluid density and viscosity compared with the base fluid. The studied volume fractions were 0.5, 1, 2, 3, and 4% and the selected nanoparticles were Al 2 O 3 , CuO, and SiC. It was found that silicon carbide nanoparticles have the best stability and the highest thermal conductivity compared to the other two nano-substances. Copper oxide nanofluid has higher thermal conductivity than aluminium oxide but lower stability, although it was found here that this material reliably stable compared to in other studies. The nanofluid reduced the indoor PV/T system temperature and enhanced its generated power. [ABSTRACT FROM AUTHOR]

Dust depositions on photovoltaic (PV) modules reduce the transmittance of PV glazing, resulting in the degradation of efficiency. The primary source of dust is wind-blown sand and soil particles from the ground. The coarse dust particles have a diameter larger than 2 μm. Photochemical reactions of gaseous pollutants in the atmosphere and dried droplets of seawater forming salt particles form most of the fine particles smaller than 2 μm in diameter. The physical properties of dust, such as specific gravity, particle shape, surface properties, moisture content, plastic and liquid limits, and particular grain size, vary from location to another all over the world. These differences are due to the topographic, geological, and environmental conditions of each region. The weight and shape of dust particles have a significant effect on their deposition behaviour and PV performance. In this paper, an investigation of energy losses caused by dust deposition on PV modules in Oman is presented. Six dust samples collected over three months from six locations in Northern Oman were investigated to evaluate their physical properties. Most of the dust particles (64%) diameters size ranged from 2 to 63 μm. The dust deposition on PV modules was found to vary from one location to another. The results indicated that there is no significant energy-yield loss caused by the low surface mass concentration of dust (<1 g/m 2 ) on the PV module. The maximum daily efficiency loss was measured and compared with that from the literature, revealing that the efficiency loss was 0.05%, which is small compared to those of neighbouring countries. However, the results show a decline in the productivity of the PV module up to 35–40% after exposure to the weather conditions for more than three months, indicating that the advisable cleaning period, is every three months. Therefore, establishing PV systems at these sites is a reasonable option. [ABSTRACT FROM AUTHOR]

The term Dust is called for any substance that spreads in the air which includes soil and dust particles (suspended dust), smoke, fog and particulate matters. It is formed from organic and inorganic substances of terrestrial origin. Such substances are like sand storms, factory smoke, bacteria, pollen, Forrest fires and volcanoes vapors. Also, they include solid atmospheric particles that stay suspended in the air for long periods, and that are able to move with wind movements for long distances. It represents large differences in volume, shape, distribution and concentrations. Dust-storms are an environmental phenomenon that transcends boundaries and their growing intensity and frequency-as a result of increasing desertification and decreasing vegetation coverage-has a tremendous negative impact on national and regional human and socio-economic development. In this study, a review of Iraqi geographical and meteorically characteristics will be made. In addition, a review of the human activities that increased desertification in Iraq areas that reflects on increasing sand and dust storms in the country will also be reviewed. The focus on dust causes, types and specifications was a priority in order to analyze its effects on PV systems. PV systems performance is affected by dust and dust storms highly influence the energy collected. A comprehensive review for the effect of dust on PV in Iraq is represented to researchers; designers and engineers dealing with PV systems in Iraq. [ABSTRACT FROM AUTHOR]

Dust accumulation on photovoltaic modules (PVs) affects performance and reduces productivity. Many parameters specify the dust effect, and the degradation is different for PV technologies. In this study, four PV modules each with a 100 W rating were installed and tested horizontally in Sohar, Oman, for an entire year. Two monocrystalline (m-Si) and two polycrystalline (p-Si), one dusty and one kept clean. The measured power, voltage, and current show the degradation where the m-Si shows more reduction compared with p-Si. According to microscopic and XRD analysis, the dust particles have a size of 25–61 µm, and the main elements are SiO2 (55.7%) and CaO (30.0%). For m-Si and p-Si, power reductions were 19% and 14%, respectively. M-Si is more affected by dust than p-Si based on its I-V characteristics. After 55 days of dust accumulation, m-Si power degradation was found to be 40%. Furthermore, the highest power degradation was found in August. The m-Si efficiency, PV performance, capacity, and yield factors are 9.24–10.76%, 52.76–72.81%, 19.53, and 140.87 Wh/Wp, respectively. The results conclude that despite the dust accumulation still, the m-Si PV module shows promising behavior and characteristics in Oman. [ABSTRACT FROM AUTHOR]

The increase in the PV cell temperature ultimately causes a reduction in its effectiveness. One of the new methods used to retain that efficiency is to establish a hybrid photovoltaic thermal PV/T system. In this study, PCM has been employed with a cooling nanofluid circulation system in order to the control heat capacitance of the system to maintain electrical efficiency on the one hand, and to raise the overall efficiency on the other. Nano-SiC particles were used in paraffin-PCM and nanofluid to establish higher thermal conductivities and therefore higher efficiency. The design is tested outdoors in Selangor, Malaysia. The tests were conducted using a fluid flow rate of 0.17 kg/s. The proposed system reduced the cell temperature (30 °C) at the peak solar radiation period (12:30 AM to 1:30 PM), which was reflected positively on the PV/T system performance. The proposed PV/T-nano PCM-nanofluid system increased the open circuit voltage from 11–13 V to 20–21 V, the power from 61.1 W to 120.7 W, and the electrical efficiency from 7.1% to 13.7%. Besides, the system made use of the thermal energy gained as its thermal efficiency reached 72%. These results ensure the adequate use of the new design. [ABSTRACT FROM AUTHOR]

The thermophysical properties of nanofluid composed of water and SiC nanoparticles without the use of a surfactant as a coolant for a PV/T system was investigated. It was observed that the addition of 3 wt% of these nanoparticles to water caused an increase in the resulting fluid density by up to 0.0082% and an increase of viscosity by up to 1.8%. Moreover, the thermal conductivity was enhanced by up to 8.2% for the tested temperature range of 25 °C–60 °C. The stability of the nanofluid was examined at intervals of three months and it was found that after six months the thermal conductivity reduced by up to 0.003 W/m K, indicating that the solution was stable and suitable for use for long periods. The use of 3 wt% SiC nanofluid increased the electrical efficiency by up to 24.1% compared to the PV system alone, while the thermal efficiency increased by up to 100.19% compared to the use of water for cooling. The final results indicated that the total effectiveness of the PV/T nanofluid system had a higher overall efficiency of about 88.9% compared to the separate PV system. [ABSTRACT FROM AUTHOR]

In the last four decades, greater attention has been paid to PV/T systems due to their advantages compared with PV or solar thermal systems alone. This paper aims to study various aspects of PV/T systems through the existing literature in order to highlight key points as future work in this field as well as illustrate different techniques used for such systems. In addition, PV/T systems are reviewed in terms of thermal and electrical side views. Furthermore, the analysis of solar thermal systems, various system applications such as air, water, air/water, phase change material PCM and Nanofluid systems are summarized. In light of most attempts to improve the PV/T system, more focus has been paid to the thermal rather than the electrical side. Furthermore, comparisons between PV/T systems in terms of performance parameters and efficiencies are presented. A critical review of many findings of previously conducted research is also discussed. It is found that the PV/T air heater system is promising for future preheating air applications. Moreover, it is suggested that the use of nanoparticles and water as base fluid improves the overall system efficiency. Furthermore, the PV side views require more attention in technical and cost terms. However, more research is essential to reduce the cost and, improve the effectiveness and technical design of such systems. [ABSTRACT FROM AUTHOR]