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According to the Food and Agriculture Organization (FAO), a large portion of the various activities in the agriculture and food supply chain (AFSC) are extremely dependent on fossil fuels and contribute to 24% of the total global greenhouse gas (GHG) emissions.There are several strategies to reduce GHG emissions and mitigate the associated destructive impacts. Among them, substituting fossil fuels with alternative low-carbon energy sources has received remarkable attention.The core concept of this study is to explore the relationship between food security, sustainable development, and renewable energy. Renewable energy has shown promising potential for integration into a wide range of agricultural activities and offers an alternative sustainable solution to current practices. In modern agriculture, the need for electrification has increased, with electric tractors and agricultural robots accounting for a large share, which represents a great opportunity for the use of renewable technologies in this sector. As new technologies emerge, investors need to familiarize themselves with them. Further technical improvements, cost reductions, and government incentives can facilitate the real-world deployment of sustainable renewable technologies in agriculture and food production.

Utilization of renewable energy in the Turkish industrial sector is becoming more important nowadays. The tendency toward renewable energy can be clearly seen with newly planned energy investments. The energy appearance of the Turkish industrial sector for past two decades and ongoing energy projects are discussed in this study with the help of sustainability indicators. The sustainability index is based on advanced exergy analysis and shows the environmental impact of production processes and measures the transformation of energy resources in the Turkish industrial sector. This index was approximately 2.03 in 2000 and it improved to 2.25 in 2008, and then remained constant with minor fluctuations until 2019. Depending on the fulfillment of the continuing fossil, nuclear, and recommended renewable energy investment scenarios, the sustainability index may change to between 1.96 and 2.17 by 2023. None of the ongoing investments will make a major improvement in the sustainability of the industrial sector; therefore, a major shift toward the use of more renewable energy is urgently needed. Establishing solar or wind energy microgrids plants may improve the sustainability indicators drastically, therefore, encouragement of their investments is very important.

In this study, three SBCs are developed as (i) SBC with phase change material (PCM: waste cooking oil and C4H4O3), (ii) a novel SBC with nanocomposite PCM (NPCM), and (iii) a SBC without NPCM. The novel proposed cooker integrated with NPCM (MgAl2O4/Ni/Fe2O3-PCM) was experimentally developed and its performance was evaluated using fuzzy logic and Cramer's rules, and image processing techniques. The results indicated that the implementation of a bar plate absorber coated with MgAl2O4/Ni-doped, Fe2O3 nanoparticles, and integrated with PCM increases the cooker's internal temperature up to 164.12 °C. The used nanocomposite materials were in the average particle size of 20 μm. The cooking materials were verified with the temperature in the segmentation process. The NPCM indicated the SBC's thermal performance enhancement of 11% in comparison with the SBC with PCM and without NPCM. Additionally, the overall thermal performance of SBCs without NPCM, with PCM, and with NPCM was obtained as 24.90–33.90%, 24.77–45.20%, and 31.77–56.21%, respectively. Moreover, the temperature of the bar plate absorber was achieved as 163.74 °C, 147 °C, and 113.34 °C for the SBC with NPCM, PCM, and without NPCM, respectively, under the solar radiation of 1,037 W/m2.

There are increasing concerns and growing regulations over contamination and environmental pollution. One of the major concerns is the pollution caused by mineral oils. As the world oil reserves are dwindling the pressures for finding alternative replacements are increasing. Vegetable oils are a biodegradable and renewable source of lubricants. Thus, they seem to be attractive candidates for the replacement of mineral oils. In this study, chemical modification of sunflower waste cooking oil through epoxidation reaction was used to improve its physicochemical properties to be used as biolubricant. Then, using the response surface method (RSM), the reaction yield was statistically modeled as a quadratic regression equation and optimal points were obtained for independent variables. The maximum amount of reaction yield was 82.9% and optimum values for independent variables were; 53.7 g of acetic acid, 30.1 g of H2O2, and 4.1 h of reaction time. The obtained optimum epoxide mixture was used as the starting material to produce SWCO triester during three chemical reactions and analyzed with the help of FTIR spectrum analysis. It was found that the physicochemical properties of the final product (SWCO triester) met the requirements of the ISO VG10 standard.

In this study, the effect of employing ZnO/Acalypha Indica leaf extract (ZAE) on the energy absorption of a coated portable solar cooker have been examined using an experimental setup. A prototypical model has been developed to corroborate in associating an investigative outcome per constituents of the experiments. The studied heat transfer process in ZAE is stable for harsh conditions. The design analysis and an estimation of the system performance were done given various parameters including the pressure of the vacuum envelope, bar plate coating digestion, emissivity, and solar rays. The fabricated solar was tested with and without ZAE to investigate the impact of this coating material on the solar cooker's thermal performance. To observe the performance of the new design, two figures of merit (F1 and F2) have been introduced. The factual food cooking assessments were for a family of four people, which operated in ZAE coating (0.8, 1.0, 1.2 \({\mu }\text{m}\)) of the solar cooker. The values of F1 and F2 for the proposed cooker were obtained as 0.1520 and 0.4235, respectively, which is intact with the BIS values. The results revealed that employing ZAE instead of a thermal NHC - PV solar cooker reduced the time required to boil 2 L of water for about 2,820 seconds. The overall thermal energy productivity of the solar cooker with electrical backup was obtained as 42.65%, indicating that the ZAE coating can improve the thermal efficiency by 10.35%.

In this study, the effect of employing ZnO/Acalypha Indica leaf extract (ZAE) on the energy absorption of a coated portable solar cooker has been examined using an experimental setup. A prototypical model has been developed to corroborate in associating an investigative outcome per constituents of the experiments. The studied heat transfer process in ZAE is stable for harsh conditions. The design analysis and an estimation of the system performance were done given various parameters including the pressure of the vacuum envelope, bar plate coating digestion, emissivity, and solar rays. The fabricated solar was tested with and without ZAE to investigate the impact of this coating material on the solar cooker's thermal performance. To observe the performance of the new design, two figures of merit (F

The world population and consequently the global need for food continue to grow. At the same time, areas will be used to generate clean electricity to cope with climate change and global warming. The combination of crop production and solar photovoltaics in the form of ""agrivoltaic technology"" offers advantages for both sides that provide an adequate, resource-efficient solution to the persistent problem of competition for arable lands. The implementation of agrivoltaic systems has been exponentially increased in recent years and reached the global installed capacity of 2.8 GW in 2020 from the initial capacity of 5 MW in 2012. The agrivoltaic systems installed worldwide mostly employ conventional opaque photovoltaic (PV) modules, causing a change in the microclimate under the panels that become critical when shading ratios are high. Semi-transparent PV (STPV) modules have been recently employed to mitigate this issue which is profoundly studied in this research by considering the use of semi-transparent technologies based on crystalline silicon (c-Si), thin-film photovoltaics, organic PVs (OPVs), dye-sensitized solar cells (DSSCs), concentrating PVs (CPVs), and luminescent solar concentrators (LSCs) in open (arable farming lands) and closed (cultivation greenhouses) agrivoltaic systems. The results indicated that c-Si STPV modules have the highest share of employment in agrivoltaic systems due to their extreme benefits of low costs, high stability, and high efficiency in comparison with other technologies, while in contrast, the use of thin-film STPV modules have been rarely reported in the literature. Additionally, STPV modules using OPVs and DSSCs offer the capability to achieve wavelength-selective transparency, causing the photosynthetic active radiation to pass through while the remained spectrum is utilized to generate electricity. Other potential solutions come from CPVs and LSCs, in which, diffuse light is available for the growth of cultivated plants, while direct concentrated sunlight can generate electricity. Although STPV modules are proven as a feasible solution for use in agrivoltaic systems, still more developments are required in terms of the modules' efficiency enhancement and costs reduction, while more detailed research is required to observe the response of cultivated plants to make this technology a viable sustainable solution in the future.

Energy transformation and sustainability have become a challenge, especially for developing countries, which face broad energy-related issues such as a wide demand-supply gap, extensive fossil fuel dependency, and low accessibility to clean energy. Globally, smart grid technology has been identified to address these affairs and enable a smooth transition from traditional to smart energy systems, ensuring energy security. This paper studies the critical role in strengthening the power system, integrating renewable sources, electrifying the transport sector, and harnessing bioenergy. Evaluating the current energy scenario in Nepal, this article presents the smart grid as a solution to existing and future energy issues and the associated challenges during its implementation, urging concerned authorities to launch initiatives to promote it. Moreover, this study also lays the foundation for future research into the smart grid's potential to reform the power sector in other developing nations with abundant renewable energy sources and similar energy-related barriers.

In this study, a small-scale two-stage multi-stage flash (MSF) desalination unit equipped with a vacuum pump and a solar parabolic collector (PDC) with a conical cavity receiver were integrated. To eliminate the need for heat exchangers, a water circulation circuit was designed in a way that the saline feedwater could directly flow through the receiver of the PDC. The system’s performance was examined during six days in July 2020, from 10:00 a.m. to 3:00 p.m., under two distinct scenarios of the MSF desalination operation under the vacuum (−10 kPa) and atmospheric pressure by considering three saline feedwater water flow rates of 0.7, 1 and 1.3 L/min. Furthermore, the performance of the solar PDC-MSF desalination plant was evaluated by conducting energy and exergy analyses. The results indicated that the intensity of solar radiation, which directly affects the top brine temperature (TBT), and the values of the saline feedwater flow rate have the most impact on productivity. The maximum productivity of 3.22 L per 5 h in a day was obtained when the temperature and saline feedwater flow rate were 94.25 °C (at the maximum solar radiation of 1015.3 W/m2) and 0.7 L/min, respectively, and the MSF was under vacuum pressure. Additionally, it was found that increasing the feedwater flow rate from 0.7 to 1.3 L/min reduces distillate production by 76.4% while applying the vacuum improves the productivity by about 34% at feedwater flow rate of 0.7 L/min. The exergy efficiency of the MSF unit was obtained as 0.07% with the highest share of exergy destruction in stages. The quality parameters of the produced distillate including pH, TDS, EC and DO were measured, ensuring they lie within the standard range for drinking water. Moreover, the cost of freshwater produced by the MSF plant varied from 37 US$/m3 to 1.5 US$/m3 when the treatment capacity increased to 8000 L/day.

In the present research work, a concave-type stepped solar still is experimentally investigated. The statistical analysis shows the influence of different variables identified on the efficiency of the still. The proposed still was fabricated with a basin area of 1 m2, a concave-type stepped aluminum basin with 10 numbers of steps, 100 mm width, and 35 mm height. Based on the experimental results, a regression model developed in Minitab 19 statistical software was proposed. Depending on the value of the R square, the appropriate model was selected. For a set of data comprising efficiency, the temperature at various locations, the intensity of radiation, and the hourly yield from the still as an input variable. The statistical results revealed that the model developed with average values recorded in March is more significant as it possesses R square = 0.9944. Hence the proposed model was suitable for the estimation of the efficiency. The highest daily productivity (3.7 l/m2. day) was achieved during March 2020. This may be attributable to the highest average intensity of the radiation (1005 W/m2) and the most top average temperature difference of 10.5 °C.

International audience; Thermal energy storage devices are vital for reducing the inconsistency between energy supply and demand as well as for enhancing the performance of solar thermal systems. The present study investigates the melting process in metallic honeycombed heat exchangers filled with n-octadacane as phase change material (PCM). Further, a parametric study is conducted for four different honeycomb cell sizes, fin thicknesses, and angles of inclinations of the computational domain. The findings are described in the form of heated surface average temperature variation, melt fraction of the PCM, and thermal energy stored. Results show that the honeycomb fin structure considerably improves the heat transfer in the PCM. Further, it was observed that the honeycomb cell size and fin thickness greatly influence the variation of the average front surface temperature, melt fraction, and energy storage rate, whereas the inclination angle doesn’t have a significant effect when cell size is less than 0.01 m. From the study, it was also observed that when the computational domain is horizontal without honeycomb cells, the pure conduction in the PCM results in much higher front surface temperature, which is greatly reduced in presence of the honeycomb cells.

This study was done to improve the productivity of an inclined solar still through some modifications include installing angle bars on the basin to increase the water residence time, fabricating the basin with adjustable inclination angle to achieve the highest amount of solar radiation in each season, installing top and bottom flat-plate external reflectors and a cooling system on the glass cover. The effect of the basin inclination angle, feeding water flow rate, cooling water flow on the glass cover, installing top and bottom reflectors at their optimum inclination angles on the productivity of the still were experimentally investigated under the climatic conditions of Tehran (35°N Latitude and 51°E Longitude) during summer, winter and spring. The results showed that in the case of applying only one modification, passing the cooling water on the glass cover has the most effect on productivity enhancement in spring while applying top reflector at its optimum inclination angle gave the best results in winter. Also, the maximum productivity of 4.2 kg/m2 was obtained for a basin inclined at 25° with top and bottom reflectors inclined at 10° and 45°, respectively. In this case, the feed water and cooling water flow rates were equal to 90 and 720 ml/min, respectively in solar radiation of 800 W/m2, air temperature of 22.5 °C, and wind velocity of 2.4 m/s. Moreover, the efficiency of the still was obtained as 36.7%, which was 14.2% higher than that of the still at an optimum inclination angle of 25° without reflectors and cooling water under the same weather conditions.

Iran holds 10% of the global oil reserves and 15% of the natural gas. It is the second largest producer and exporter of oil and gas in Organization of the Petroleum Exporting Countries (OPEC). The consumption of energy in Iran is 4.4 times higher than the global average, placing it among the world's top ten greenhouse gas (GHG) emitters. According to the published statistics, renewable energy (RE) has faced a considerable growth in Iran due to the strategies of the sixth development plan, which aims at generating 5000 MW from REs by 2021, and an additional 2500 MW by 2030. The other reason is that under the “Paris Agreement” terms, Iran obliged to reduce its GHG emissions by at least 4% and at most 12% by 2030. Among RE resources, Iran has the remarkable potential for solar energy with the average annual rate of 4.5–5.5 kWh/m2. Under these conditions, solar photovoltaic (PV) power plants can play a crucial role in supplying a significant portion of the country's electricity demand. Although there is a high tendency of the government and policy makers for deployment of PV technology in Iran, there are still some impediments to turn potential into reality in this sector due to insufficient industry growth, financing problems, deficient of governing rules, and lack of a sustainable development roadmap. Solving these issues requires long-term and persisting policies to gain technical and industrial development to achieve mass progress in this sector during the next decades.

Fibre reinforced plastic (FRP) basin solar still is manufactured and marketed commercially in developing/underdeveloped nations. Unfortunately, these commercial units have not been widely adopted by the public due to its low water productivity. In the present investigation, an effort has been made to assess the performance and enviro-economic aspects of the commercial unit and its low-cost improved versions under Coimbatore climatic conditions through real-time experiments and mathematical models, respectively. The commercial unit has distillate productivity of about 2.76 L/d under cumulative solar radiation intensity of 24.37 MJ/m2d and it increased up to 6.03 L/d with the addition of black dye and thermocol insulation. Yearly average distillate production rate, thermal efficiency, and exergy efficiency of the improved version is about 4.36 L/d, 53.62%, and 6.89%, respectively. The greenhouse payback time of the commercial unit and insulated commercial unit with black dye is about 2.39 and 1.81 Years, respectively. Global warming potential, acidification potential and photochemical oxidant formation potential of the commercial unit decreased from 0.27 to 0.12 kg of carbon di-oxide eq/L of distillate, 2.40 to 1.05 g of sulphur di-oxide eq/L of distillate and 0.73 to 0.32 g of ethylene eq/L of distillate, respectively with the incorporation of low-cost improvement techniques. The sustainability index of the improved version is around 5.94% higher than the sustainability index of the commercial unit. The distillate production cost of improved version (1.32 INR/L) is closer to reverse osmosis (RO) water supplied to Indian houses (1.00 INR/L). The incorporation of low-cost improved techniques to the commercial unit makes it an attractive option for sustainable potable water production. However, proper marketing and awareness strategies must be adopted by stakeholders to make this improved version acceptable among the public.

The greenhouse industry is an energy-intensive sector with a heavy reliance on fossil fuels, contributing to substantial greenhouse gas (GHG) emissions. Addressing this issue, the employment of energy-saving strategies along with the replacement of conventional energy sources with renewable energies are among the most feasible solutions. Over the last few years, solar energy has demonstrated great potential for integration with agricultural greenhouses. The present study reviews the progress of solar greenhouses by investigating their integration with solar energy technologies including photovoltaic (PV), photovoltaic-thermal (PVT), and solar thermal collectors. From the literature, PV modules mounted on roofs or walls of greenhouses cause shading which can adversely affect the growing trend of cultivated crops inside. This issue can be addressed by using bifacial PV modules or employing sun trackers to create dynamic shades. PVT modules are more efficient in producing both heat and electricity, and less shading occurs when concentrating modules are employed. In terms of using solar thermal collectors, higher performance values have been reported for greenhouses installed in moderate climate conditions. Further, in this review, the employment of thermal energy storage (TES) units as crucial components for secure energy supply in solar greenhouses is studied. The usage of TES systems can increase the thermal performance of solar greenhouses by 29%. Additionally, the most common mathematical models utilized to describe the thermal behavior of solar greenhouses are presented and discussed. From the literature, machine learning algorithms have shown a better capability to describe the complex environment of greenhouses, but their main drawback is less reliability. Notwithstanding the progress which has been made, further improvements in technology and more reductions in costs are required to make the solar greenhouse technology a solution to achieve sustainable development.

Floating Photovoltaic (FPV) is an emerging technology that has experienced significant growth in the renewable energy market since 2016. It is estimated that technical improvements along with governmental initiatives will promote the growth rate of this technology over 31% in 2024. This study comprehensively reviews the floating photovoltaic (FPV) solar energy conversion technology by deep investigating the technical advancements and presenting a deliberate discussion on the comparison between floating and ground-mounted photovoltaic (PV) systems. Also, the economics and environmental impacts of FPV plants are presented by introducing the main challenges and prospects. The FPV plants can be conventionally installed on water bodies/dam reservoirs or be implemented as multipurpose systems to produce simultaneous food and power. Installing FPV modules over water reservoirs can prevent evaporation but penetration of solar radiation still remains an issue that can be eliminated by employing bifacial PV modules. The salt deposition in off-shore plants and algae-bloom growth are other important issues that can degrade modules over time and adversely affect the aquatic ecosystem. The capital expenditure (CAPEX) for FPV systems is about 25% higher than ground-mounted plants, mainly due to the existence of floats, moorings, and anchors. It has been stated that the capacity increase of FPV plants (ranges from 52 kW to 2 MW) can intensely decrease the levelized cost of energy (LCOE) up to 85%. It is estimated that FPV technology can become more affordable in the future by further research, developments, and progress in both technology and materials.

This article was developed to review the application of Life Cycle Assessment (LCA) in systems that produce materials and energy from agricultural residues, like Wheat Straw (WS) in the context of a circular bio-based economy. Attention was focussed upon WS, because it was documented as a valuable feedstock for biorefinery applications, thus highlighting the value of a systematic literature review of this content area. The study documented that WS is being used for production of biofuels and bioenergy in technically and environmentally sound processes. However, WS biomass is somewhat less environmentally and economically beneficial than biomasses such as Corn Stover (CS) and forest residues, mainly due to their higher ethanol potential and production yields. The LCAs reviewed for this paper evaluated the alternative sustainability dimensions of biorefinery systems and focussed upon advancements and challenges in implementing WS-derived ethanol systems. Further research is needed to optimise the WS bio-energy production processes so comparative studies can be done to make improvements of the environmental, and socio-economic dimensions of bio-energy production and usage within circular economies.

With an uprising trend in cutting agriculture’s reliance on fossil fuels because of their limited supply and associated adverse impacts on the environment, the use of infrastructures adapted with alternative energy sources would be of crucial necessity. Among all renewable sources, solar energy has the highest compatibility with agricultural activities. The emergence of photovoltaic (PV) solar energy conversion technology in agriculture diminishes the need for oil-based fuels in this sector, offering a more affordable and sustainable electricity generation technique, and causing a remarkable reduction in greenhouse gas (GHG) emissions. In modern farm activities, the need for electrification has been raised, leading to the creation of a great opportunity for the employment of PV technology in this sector. The current study investigates the integration of PV technology with electric farm tractors and agricultural robots by discussing research works and commercial case studies. The results indicate that two major challenges against the widespread deployment of modern solar-powered electric farm machinery are high initial costs mainly associated with PV modules and battery storage units, along with deficiencies in electricity storage technologies. Due to operating in outdoor conditions, the effect of environmental parameters on the performance of PV modules integrated with agricultural machines including surface temperature, dust accumulation, shading, and air humidity should also be considered. Further technical improvements, cost reductions, and securing government incentives can facilitate the real-world deployment of these sustainable machines. This study is expected to promote the integration of PV technology with modern electric agricultural machinery and to encourage farmers, producers, planners, and decision-makers to employ this technique in mechanized agriculture by giving them an insight into the latest advances along with major challenges.

Renewable energy policies emphasize both the utilization of renewable energy sources and the improvement of energy efficiency. Over the past decade, built-in photovoltaic (BIPV) technologies have mostly focused on using photovoltaic ideas and have been shown to aid buildings that partially meet their load as sustainable solar energy generating technologies. It is challenging to install conventional photovoltaic systems on curved facades. In this research, elastic solar panels assisted by flexible photovoltaic systems (FPVs) were developed, fabricated, and analyzed on a 1 m2 scale. A flexible structure on a flat, hemispherical, and cylindrical substrate was studied in real terms. Using the LabVIEW application, warm and dry climate data has been recognized and transmitted online. The results showed that when installed on the silo and biogas interfaces, the fill factor was 88% and 84%, respectively. Annual energy production on the flat surface was 810 kWh, on the cylindrical surface was 960 kWh, and on the hemisphere surface was 1000 kWh, respectively. The economic results indicate that the net present value (NPV) at a flat surface is USD 697.52, with an internal rate of return (IRR) of 34.81% and a capital return term of 8.58 years. Cylindrical surfaces and hemispheres each see an increase of USD 955.18. The investment yield returned 39.29% and 40.47% for cylindrical and hemispheres structures. A 20% increase in fixed investment in the flat system increased IRR by 21.3%, while this increase was 25.59% in the cylindrical system and 24.58% in the hemisphere. Research innovation is filling the gap on the use of flexible solar panels on curved and unconventional surfaces.

An experimental analysis of a stepped solar box cooker (SSBC) improved using energetic SiO2/TiO2 nanoparticles. They were used in different ratios between 5% to 25% as a coating on a bar plate to enhance thermal performance. The SSBC was assessed experimentally to obtain a cost-effective solution and the best performance for the bar plate temperature, enabling increased cooking activities performance. The furious SiO2/TiO2 nanoparticles were coated over a bar plate, which allows them to absorb more solar radiation and increase the system of inner moist air temperature. The SiO2/TiO2 nanolayers used as 15% improved overall thermal efficiency by 31.42% of the system. The bar plate performances coated with SiO2/TiO2 nanolayers and used in SSBC were compared to other doping nanoparticles percentage for their solar thermal characteristics. The SiO2/TiO2 nanolayers coated by the SSBC is enabled to increase the performance by about 31.77%, 37.69%, 49.21%, 36.99%, and 34.66% when was used 5%, 10%, 15%, 20%, and 25%, respectively and compared to that of single nanolayers (SiO2, TiO2) of convention cooker.

Photovoltaic (PV) is one of the most promising and prominent techniques for electricity generation based on solar energy. It is expected to play a dominant role in providing future global electricity demand. Although PV modules are basically employed to provide electricity, the heat extraction from these modules has also been part of numerous studies and has created an emerging technique known as photovoltaic thermal (PVT), in which both electricity and heat can be produced simultaneously. Although the development of PVT modules originates from the cooling techniques of the PV modules, numerous types have emerged according to thermal module designs, types of working fluid, types of utilized solar cells, applications, etc. In this chapter, different types of PVT modules based on their geometry, working fluid, and applications including flat-plate, concentrating, and some innovative designs such as integration of PVT modules with heat pipes, thermoelectric (TE) modules, refrigerant cycles, and phase change materials (PCMs) as well as beam splitting PVT (BSPVT) modules have been introduced and deliberately discussed.

Water scarcity is a serious problem in several regions, especially in isolated communities located in desert or arid areas of the world. One of the most promising solutions to address this problem is desalination. Solar photovoltaic (PV) power generation technology has demonstrated that it can be an ideal and clean alternative to fossil fuels, especially in remote and isolated areas where there is no accessibility to power grids, or such accessibility is difficult. The integration of desalination plants with solar PV systems for water production is nearly competitive because of both the decreasing trend of PV prices and the increasing trend of fossil fuel prices over recent years. The generated electricity by PV systems integrated with desalination plants can be utilized to drive electromechanical devices, including pumps and fans, electric heaters, etc., and in a larger range, any direct-current (DC) apparatus. The most mature conventional desalination technologies for integration with solar PV systems are reverse osmosis (RO) and electrodialysis (ED). Due to operating RO based on alternative current (AC), a DC/AC inverter is required while ED systems operate based on DC current. Membrane distillation is another desalination technology that requires thermal power to operate, but PV modules can also be integrated to supply the required electricity for other attached equipment. In addition, the integration of PV modules with solar stills, which are the most favorable alternatives in remote areas for supplying freshwater, has great potential to overcome some of the problems regarding conventional distillation systems. In all mentioned PV-powered desalination systems, energy storage or an electricity back-up system is critical to guarantee sustained operation. The main barrier for worldwide deployment of PV-powered desalination systems is the high investment costs, resulting in high produced water costs. However, there is huge potential for further enhancement of performance, energy savings, and cost reductions.

Solar energy as a plentiful and environment-friendly source of energy has an acceptable potential in nearly most of the regions around the world. Thermal technologies are commonly used to provide heat requirements of different domestic, agricultural, residential, and industrial applications from the sun. This paper reviews thermal performance enhancement techniques of the most widely-used low-temperature solar collectors (LTSCs) including flat-plate collectors (FPCs), evacuated tube collectors (ETCs), and compound parabolic concentrators (CPCs) by introducing challenges and discussing future research potentials. In this regard, energy analysis of each collector type along with the latest advancements to boost the heat collection capability of the LTSCs reported in the previous studies is presented. The discussed methods in this study broadly cover structural modifications, absorber coatings, integration with reflectors, using alternative working fluids including nanofluids, and employing thermal energy storage (TES) systems. This comprehensive review is reflecting the level of technical maturity of each type of LTSCs and is expected to serve scientists, engineers, and developers with the latest achievements in this technology.