مساعد محمد سعيد الزهراني

البحوث المنشورة

Estimation of The Performance Limits of a Concentrator Solar Cell Coupled with a Micro Heat Sink Based on a Finite Element Simulation

https://doi.org/10.1016/j.applthermaleng.2020.115315

14/04/2020

Concentrated photovoltaic (CPV) technology makes use of cheap optical elements to amplify the irradiance and focus it on small-sized solar cells enabling the extraction of higher amounts of electricity. However, increasing the solar concentration raises the temperature of the PV cell which can deter its performance and can also cause its failure. To combat this issue both active and passive cooling mechanisms are utilized for different types of CPV systems. In this study, we determine the limits of passive cooling systems and establish when an active cooling system is needed based on the recommended operating temperature of the solar cell. We investigate the temperature characteristics of the solar cells bonded to three different substrate materials under different solar concentrations. Results showed that cell temperature is linearly dependent on the concentration ratio and ambient temperature independent of the substrate material. Further, the integration of a micro-finned heatsink results in higher heat dissipation by 25.32%, 23.13%, and 22.24% in comparison with a flat plate heatsink for Direct Bonded Copper (DBC), Insulated Metal Substrate (IMS), and Silicon Wafer (Si wafer) substrates respectively. The low thermal resistance of the IMS substrate compared to the DBC and the Si wafer substrates result in the best thermal performance in terms of maintaining the cell temperature < 80 °C and allowing a wider range of high concentration ratio.

Optical Losses and Durability of Flawed Fresnel Lenses for Concentrated Photovoltaic Application

https://doi.org/10.1016/j.matlet.2020.128145

10/06/2020

Recycling optical devices and materials for solar concentrator devices is a relatively unstudied area but one which is likely to grow in importance as we progress towards an increasingly sustainable and minimum waste environment. As such, considerations into major optical flaws are required. Here, we have investigated the durability of a cracked Silicon on Glass (SOG) Fresnel lens incorporated as the primary optical component in a concentrated photovoltaic (CPV) application. Optical and electrical characterisations of the flawed glass have been conducted to show the effect on the performance. The optical characterisation has shown a drop of 3.2% in optical efficiency. As well, I-V and power curves of cracked and non-cracked Fresnel lens were compared to shows a drop of 3.2% in short circuit current (Isc) and power. The results have confirmed that the power loss is directly related to only the area of the primary optic flawed, which has been calculated through as a percentage of geometrical loss (a form of shadowing) which was estimated to be 2.7% of the concentrator area. From the results, we can confirm that although the performance has slightly declined for the significantly flawed Fresnel lens, there are no other detrimental optical effects. The durability of such optics still needs to be tested, but from these results, we recommend that similarly critically flawed optics can be utilised, likely in non-demanding singular CPV units where <5% loss is acceptable.

Effect of Using an Infrared Filter on The Performance of a Silicon Solar Cell for an Ultra-High Concentrator Photovoltaic System

https://doi.org/10.1016/j.matlet.2020.128332

13/07/2020

It is well known that increasing the concentration ratio of concentrator photovoltaics has a positive impact on the power output of the system but can reduce the solar cells performance due to the heightened temperatures. In this paper, we introduce the impact of using an infrared (IR) filter on the performance of a silicon solar cell as a preliminary investigation for an ultra-high concentrator photovoltaic system. The investigation is carried out in terms of the optical characterization of the Fresnel lens and the IR filter. Besides, the performance of the system has been introduced in this paper. The results show that although the IR filter protects the solar cell from damage near the tabbing wire, it reduces the experimental power output of the cell by 46.08% due to the low transmittance of the filter while the cell efficiency increased by 183.3%.

Advances and Limitations of Increasing Solar Irradiance for Concentrating Photovoltaics Thermal System

https://doi.org/10.1016/j.rser.2020.110517

03/11/2020

Concentrating photovoltaic-thermal (CPVT) technology harnesses solar energy by increasing the solar density upon cells using optical concentrators. CPVT systems are the focus of ongoing research and improvements to achieve the highest potential for energy harnessing and utilization. Increasing the concentration ratio for high energy generation raises many advances and limitations in the CPVT design. This article highlights the influence of the temperature with an increasing concentration ratio on CPVT components in terms of single-/multi-junction semiconductor materials, primary and secondary optical concentrator materials, and thermal receiver design. To achieve this, the theory of single- and multi-junction solar cell electrical characteristics (V_oc,I_sc,FF and η) is first explained to understand their dependence on the temperature and concentration ratio. An extensive literature review discussing the advantages, disadvantages, and potential of current CPVT research is given. This includes graphical and tabular summaries of many of the various CPVT design performances.

In this review, it has been ascertained that higher concentration ratios raise the temperature at which the performance, operation and reliability of CPVT system are affected. Also, this review indicates that the temperature elevation of the CPVT components is significantly impacted by the optical configuration and their material types and reflectance. A thermal receiver is illustrated as three components: solar cell (heat source), heat spreader (substrates) and its different types, and cooling mechanism. In addition, the article addresses the thermomechanical stress created with intensified illumination, especially with secondary optics, where the optical materials and optical tolerance need to be carefully explored. The economic implications of a high concentration ratio level are briefly considered, addressing the reduction in system cost by enhancing the system efficiency. Suggestions are made throughout the review as to possible improvements in system performance.

Graphene as A Pre-Illumination Cooling Approach for A Concentrator Photovoltaic (CPV) System

https://doi.org/10.1016/j.solmat.2020.110922

16/12/2020

The concentrator photovoltaic (CPV) system has a high potential in increasing the power output, propelling further the concentration ratio generating excessive heat that significantly deteriorates the solar cell efficiency and reliability. To thoroughly exploit graphene as a pre-illumination cooling technique for a solar cell, we experimentally characterized screen printed graphene coating (GC) physicochemical characterizations to observe the attenuation of light across a wide wavelength range with different GC thicknesses on a low iron-glass. The thermal and electrical characterizations were further executed to observe the performance of GC on a concentrated CPV system. Based on these comprehensive experimental characterizations, the concept of utilizing graphene as a neutral density (ND) filter for focal spot CPV system is shown to reduce the device temperature significantly by 20% and 12% for GC6.3 (6.3 μm thickness) and GC2.2 (2.2 μm thickness) in comparison with the infrared filter, respectively. It has been observed that GC6.3 increased the cell efficiency by about 12% at 8 suns compared to the base case at 400 W/m2 producing 7 suns. It has been ascertained that the introduction of graphene as the ND filter component improved the solar cell efficiency instead of just reducing the geometrical concentration ratio. Further, even the most susceptible single-junction solar cell under a concentration ratio of ≈20 suns with no cooling aid has shown an excellent cell efficiency. Therefore, our approach envisages its application for non-CPV and high and ultrahigh CPV system incorporated with a triple-junction solar cell eliminate the use of external heat sinks or other cooling arrangements.