Abstract In recent years, researchers are fascinated to counter problem of PV-efficiency decline arising from high operating temperatures, especially in hot climates. This article conducts a comprehensive review of research activities performed in last 5 years, on cooling techniques with phase-change materials (PCMs), nanofluids and their combined use, leading to efficiency enhancement. By passive cooling approach with PCMs, it is found that maximum enhancement up to 20% in PV-efficiency can be achieved. Effectiveness of PCM for PV is more prominent in summer than in winter. Incorporations of fins inside PCM container at PV rear, results in much improved heat conduction within PCM. Now-a-days, researchers have grown interest in composite PCMs for PV cooling due to their enhanced thermal conductivity. Moreover, better heat regulation as well as PV-surface temperature uniformity can be achieved with two PCMs at a time having different melting points. Studies suggest that combination of passive & active cooling techniques helps in further lowering of PV-cell temperature, leading to enhancement in PV-efficiency with additional thermal power generation. PV-efficiency of water-based hybrid PV/T systems can be improved by 32% by integration with PCM. Although nanofluid-based PV/T systems have been proved to enhance PV-efficiency by more than 60%, but combined use of PCM & nanofluid is more effective approach for PV cooling than individual use of PCM or nanofluid. If combination is made between nanofluid & nano-PCM, electrical power & efficiency can further be enhanced. Nanofluids can also be considered a good spectral filter alternative as they require small thickness and are able to be tuned by varying nanoparticles conc. Finally, environmental impacts & economic viability of mentioned cooling techniques, were discussed. Studies show that PV/PCM systems become expensive & less feasible when operated in single junction due to long payback period up to 20 years. Economic feasibility can be increased by combining passive & active cooling techniques which can increase system compactness and lower its cost.

中文翻译：

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集成基于相变材料的系统的光伏冷却和效率增强的最新进展——全面回顾

摘要 近年来，研究人员着迷于解决因工作温度高引起的光伏效率下降问题，尤其是在炎热气候下。本文对过去 5 年中进行的研究活动进行了全面回顾，这些研究活动涉及相变材料 (PCM)、纳米流体及其组合使用的冷却技术，从而提高了效率。通过采用 PCM 的被动冷却方法，发现可以实现高达 20% 的光伏效率最大提高。相较于冬季，PCM 对光伏的有效性在夏季更为突出。在光伏后部的 PCM 容器内加入翅片，大大改善了 PCM 内的热传导。如今，研究人员对用于光伏冷却的复合 PCM 越来越感兴趣，因为它们具有增强的导热性。而且，同时使用两种具有不同熔点的 PCM 可以实现更好的热调节和 PV 表面温度均匀性。研究表明，被动和主动冷却技术的结合有助于进一步降低光伏电池温度，从而通过额外的热发电提高光伏效率。通过与 PCM 集成，水基混合 PV/T 系统的光伏效率可提高 32%。虽然基于纳米流体的 PV/T 系统已被证明可将 PV 效率提高 60% 以上，但与单独使用 PCM 或纳米流体相比，PCM 和纳米流体的组合使用是更有效的 PV 冷却方法。如果在纳米流体和纳米PCM之间进行组合，可以进一步提高电力和效率。纳米流体也可以被认为是一种很好的光谱过滤器替代品，因为它们需要很小的厚度并且能够通过不同的纳米颗粒浓度进行调整。最后，讨论了上述冷却技术的环境影响和经济可行性。研究表明，由于长达 20 年的投资回收期，PV/PCM 系统在单节点运行时变得昂贵且不太可行。通过结合被动和主动冷却技术可以增加经济可行性，这可以增加系统的紧凑性并降低其成本。由于长达 20 年的投资回收期，在单节点运行时不太可行。通过结合被动和主动冷却技术可以增加经济可行性，这可以增加系统的紧凑性并降低其成本。由于长达 20 年的投资回收期，在单节点运行时不太可行。通过结合被动和主动冷却技术可以增加经济可行性，这可以增加系统的紧凑性并降低其成本。