Recent technical approaches for improving energy efficiency and sustainability of PV and PV-T systems: A comprehensive review

Photovoltaic (PV) technology is recognized as a sustainable and environmentally benign solution to today's energy problems. Recently, PV industry has adopted a constant effort to enhance module power up to 500 W with prolonged stability of crystalline silicon for around 25-30 years. Such progress contributed to a 10-fold cost drop since the early 2000 s, reaching less than 0.20 €/Wp as of October 2020. At the same time, the scientific community has also followed multiple ways and approaches to improve the performance of PV systems and make them more economically and sustainably attractive. Although various works in the existing literature have dealt separately with these approaches, this review paper reassembles all the available techniques and strategies in a unique reference and combined fashion with a special focus on novel techniques. This paper comprehensively reports the most recent approaches and techniques developed by researchers worldwide to improve PV modules' performance. First, a review of PV technology from a material science point of view is given. Performance and economic indexes used to assess the viability of solar PV technology are then given. Recent progress on photovoltaic/thermal (PV/T) systems, sun-tracking mechanisms, bifacial PV configurations, floating and submerged PV systems is summarized, as well. Most recent novel combined approaches for enhancing the performance of PV systems are being reported here for the first time. Moreover, the current study also sheds light on perspectives and challenges for PV technology from an engineering point of view. Overall, PV technology demonstrates a great ability to reach the expected installed capacity by 2030 with decreasing cost trends. The global PV/T capacity that increased by an average of 9 % per year between 2018 and 2020 indicates promising development perspectives, especially in Europe. Last but not least, the floating PV and AgroPV systems are destined to grow.