A comprehensive review of solar-assisted technologies in India for clean water and clean energy

Abstract

This article discusses the solar-assisted technologies from the Indian subcontinent to address the sustainable development targets developed by the United Nations program. For water and renewable energy, technologies presented in this paper include carbon sequestration, solar biomass, power plants with thermal and photovoltaic systems, irrigation systems, heating systems, dryers, distillation systems, solar desalination, and water treatment. Various techniques are suggested for clean water recovery using solar distillation, solar stills, and desalination. Various methods of solar drying the fruits and vegetables have been discussed using flat-plate collector. Power production from solar–thermal, solar–photovoltaic, and solar–biomass systems are covered from recent studies. Prospects on future solar energy research is recommended on solar cells, magnetized solar stills, heat pump-integrated solar power production systems, and plasmonic nanofluids in solar collectors. In conclusion, the outlook for solar technologies is examined.

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1. Introduction

The world is looking for low-cost nonconventional energy sources (such as wind, biomass, solar, nuclear, geothermal, etc.) due to the rise in global oil costs. Around 1.7 GW of energy is produced globally by solar thermal resources [1]. In the past 20 years, researchers and engineers have become interested in these energy sources due to their potential advantages in domestic water heating systems. Energy demand has increased dramatically as a result of rising electricity dependence and citizen access. Power generation also gets increasingly expensive as conventional energy sources are depleted. The usage of renewable energy sources should be enhanced for development that is sustainable in order to meet energy needs. Even though they currently provide a much smaller contribution, renewable energy sources are nevertheless important. The percentage of energy produced from biomass, geothermal, solar, and wind sources is only 6.3%. Solar energy accounts for only 4.6% of the total contribution of renewable energy [2].

When combined with the appropriate thermal storage devices, large energy content from solar radiations can be employed for heating. Due to the numerous applications of solar radiation over the last 10 years, air heating with sunlight has emerged as one of the most promising applications for producing hot air in space heating, desiccant regeneration, drying agricultural products, food and textile industries, etc. Numerous journals have published studies for the creation and testing of solar-powered air heating systems. Air has been heated using solar radiation, utilizing a variety of collectors, such as evacuated tube-type solar collectors, parabolic trough collectors, and flat-plate collectors. The demand for energy is expected to triple by the end of the twenty-first century. The world’s energy sector is rapidly turning more and more to renewable energy sources due to the limited supply of traditional fuels and their low-energy output. Solar energy is one of the many renewable energy sources that is widely accessible. Solar energy can be used for a multitude of purposes, including boiling water, purifying saline water, and drying fruits, vegetables, and other agricultural products, all with the help of several inexpensive tools.

When world leaders gathered in 2015 to adopt the 2030 Agenda for Sustainable Development and its 17 Sustainable Development Goals (SDGs), they made a historic commitment to protect everyone’s rights and well-being on a healthy, vibrant planet. The realization that social progress, environmental preservation, and economic growth must all be incorporated into sustainable development is reflected as SDG. SDG #7 focuses on guaranteeing that everyone has access to inexpensive, clean energy, which is essential for the growth of business, communications, agriculture, healthcare, education, and transportation. Since energy prices are rising daily, we can encourage solar energy by improving our financing strategy and fostering trust among all stakeholders. Two of the most important sustainable development objectives are “sustainable green energy for all (SDG-7)” and “ensuring access to clean water and sanitation (SDG-6).” Making drinkable water from saltwater is a sustainable method. Because solar stills have no negative effects on the environment, they operate sustainably. This lessens the harmful effects of traditional desalination on the environment. Reducing CO₂ emissions and global warming can be greatly aided by the use of solar technology, such as solar desalination.

Solar–biomass hybrid operations conserve biomass and land as compared to biomass-only operations by nearly 29%, which raises the cost per energy loss and levelizes the cost of energy. As feedstock, fossil fuel, and land prices continue to rise and the cost of solar thermal power decreases, hybrid plants will become a more and more appealing alternative. Trigeneration facilities should receive preferential subsidies as solar energy will continue to depend on them in the near future. Certain desalination units are intended to remove salt from the area’s geothermal water, which is very shallow and hence appears as groundwater when it is dug up for drinking. High-quality freshwater with a very low salt percentage is the goal of a multistage flash (MSF) distillation system. This plant may be used to produce both freshwater and salt from the released brine. The solar evacuated tubes serve as a source of energy, making the entire system sustainable and environmentally friendly. Based on the required temperature for the MSF system, solar collectors were chosen. In addition to producing salt, this system will be able to meet the people’s need for drinking water. There are further uses for the system’s rejected heat, such as food drying and balneology.

India’s energy consumption has been driven by the country’s recent strong economic reformation. Fossil fuels make up the majority of the energy mix in India; a large portion of these fuels are imported, and as energy consumption has increased, so have fossil fuel imports and greenhouse gas (GHG) emissions. These have important consequences for India’s energy security, ability to combat climate change, and sustainable development. In response to these issues, the Indian government has implemented a number of initiatives to decrease the use of fossil fuels, among them is the Jawaharlal Nehru National Solar Mission (JNNSM), unveiled in 2009. Several researchers contributed to the discovery of new solar technologies, and the breakthrough achievements are listed here under various fields of application. The accomplishments in the solar-assisted technologies in Indian subcontinent during the recent years are discussed in this review. The future prospects on the usage and implementation of solar technologies are also presented at the end.

2. Clean water production from solar energy

A patented water-purifying device driven by solar-generated renewable energy was developed by solar water solutions. People can obtain safe drinking water through the solar water outlets, irrespective of whether they live in rural places, areas with contaminated or salinized water resources, or both. Many people still would not have access to clean drinking water in the absence of this breakthrough. Furthermore, solar water solutions offer a desalination method that is safe for the environment. Groundwater and saltwater can both be made drinkable with solar water technologies. Moreover, there are no production-related emissions, meaning that the carbon footprint is negligible.

2.1 Solar desalination technologies

One method of desalinating water with solar energy is solar desalination [3]. Using this technology, desalination can be achieved in two fundamental ways: direct and indirect. In some indirect ways, sunlight can power a membrane process by converting to energy. It can also generate heat for evaporative desalination procedures. Environmental effects from future technological developments should not be unfavorable. The thermal pollution results from modern air conditioning (A/C) systems’ rejection of heat into the environment. Heat is required for thermal desalination processes, such as humidification–dehumidification (HDH). As a result, the HDH in the current development uses the A/C unit’s heat rejection. The heat-absorbing capacity of A/C has also been utilized for dehumidification by HDH technique. With an upgrade, the refrigerator unit can now function as a heat pump. The unit’s coefficient of performance (COP) is increased when a refrigerator and heat pump are used simultaneously. Table 1 presents the comparison of desalination technology with its productivity at different locations in India. Next, we discuss some studies on desalination using solar technologies attempted in India.

Two types of solar stills, standard solar stills and advanced solar stills, were researched using a nanophase transition material (zinc oxide) [26]. A solar still outperforms conventional technology by roughly 113% in terms of yield and maximum thermal efficiency, with 51% and 6600 ml/m², respectively, under the same climatic conditions. A nanostructure with minute surface dents are formed with random pores on the surface at 5°C. The created nanostructures were used in solar-powered desalination and the developed solar still had 27% higher evaporation rate than the conventional solar still [27]. Various desalination systems [28] that use renewable energy sources are reviewed, including a thorough analysis of all direct and indirect solar desalination systems, as well as plant-specific technical information and financial viability.

Numerous enhancing approaches, such as sandblasting, milling, and shot-blast-assisted corrugation, are used to explore the energy, exergy, economic, and environmental evaluation of single-slope solar stills [29]. Both the exergy payback time and the exergoeconomic factor are positive for shot-blast-assisted corrugation. To investigate the creation of freshwater, cooling, and hot water, the theoretical cycle of HDH (Fig. 1) and vapor compression refrigeration is suggested [30]. With 1000 m³/hour airflow, the system produced 5 L/hour of freshwater at 3.8 energy performance ratio (EPR) with 6.5 kW of cooling. Various steps have been designed, created, built, tested, and experimented to desalinate seawater using multiple effects and solar energy [31]. The brine and condensate are sent to the last stage using just solar energy, where there is a greater 13°C temperature difference between the condenser cooling water’s entrance and outflow. A green desalination system is introduced by using solar evacuated tubes and a MSF distillation system to desalinate geothermal water [4]. The simulation produced satisfactory results, with the salt concentration reduced to 194 ppm and the estimated cost of water per cubic meter being 0.1034 USD. The salinity level is examined along with water quality parameters in samples of underground water taken from Chennai’s coast [32]. An effective solar desalting process for solar-aided desalination still effectively improved the quality of the water for domestic uses while offering a low-cost solution for producing potable water. The inexpensive, easily accessible thermal storage materials, such as pebbles, are the main focus of the experimental research on solar desalination systems [33]. It has been discovered that a solar desalination unit’s distillate output is greatly affected by the use of thermal storage materials both during the day and at night. An HDH desalination system is designed, tested, and powered by solar energy in Kerala, India, using a multistage bubble column dehumidifier [5]. Converting the single-stage setup to a two-stage configuration results in increases of 6.24%, 6.75%, and 17%, respectively, in freshwater yield, gain-output ratio, and efficacy. A concentrated photovoltaic–thermal (PV-T) collector, an ejector refrigeration cycle, an active solar still for fresh water, and an organic Rankine cycle with integrated cooling are among the proposed systems [34]. Three environmentally friendly refrigerants—R152a, R1234ze, and R1233zd—are used to study the system. Its overall energy efficiency is 4.15%, and its performance index output is 0.351. For this intended multigeneration system, R152a is suggested as the ideal refrigerant due to its efficiency and environmental friendliness. Activated carbon nanoparticles are mixed with ordinary black paint to boost the effectiveness of low-cost solar-powered desalination systems in solar stills [35]. The modified system showed a noticeable increase in absorber (14.5%) and average water temperature (12.5%). Comparing solar-based desalination technique operating principles and global energy statistics to other energy-intensive combination solutions in water purification methods highlights the importance of these aspects [36]. The impact of wind, water depth, and phase-change material (PCM) thickness are examined with plans to address the gap in the literature on distillate production [37]. It also describes the methods to improve a number of active and passive stainless steel (SS) for small and large applications, with and without PCM. A novel nanoporous Cr–Mn–Fe oxide nanocoating still is made by using a mirror-polished SS202 sheet as the basin liner for the nanocoated solar still and an acidic mixture of 21–34 weight percent concentrated H₂SO₄, 37.5–53 weight percent distilled water, and 15–30 weight percent sodium dichromate salt [8]. Calculations of GHG emissions, carbon dioxide mitigation, carbon credit gained, energy-payback time, energy production factor, life cycle conversion efficiency, and suitability of distilled water for drinking are made using eco-economic studies, energy matrix evaluation, and water quality analysis. From the above research techniques, it is evident that solar desalination is an energy-intensive process that requires a lot of electricity. To overcome this challenge, solar distillation process is found to be effective and discussed in the following section.

2.2 Solar distillation technologies

Freshwater from a big body of water, like a sea or lake, can be evaporated using sun energy through a process called solar distillation. The method solves the problem of restricted access to fresh water more profitably in small, isolated places or desert regions. The method provides good prospects for large-scale production scaling and is very advantageous at the household level. The collected water is not heated to a boiling point in solar stills or distillers. Therefore, they do not eradicate dangerous chemicals or eradicate microorganisms.

The two main principles of solar water distillation are condensation and evaporation. Fresh water is separated from brackish or salty water using these two principles. As a result, the freshwater that is produced can be used for drinking, cooking, cleaning, and other household needs. The process of solar water distillation [38] uses very little energy. Distillation procedure is a less expensive way to obtain clean drinking water than desalination. Next, we present some research activities dealing with the solar still.

The effects of water depth at a constant air gap are investigated, and a unique noncontact nanostructure that is thermally and physically isolated from the solar still’s internal water is produced via a chemical oxidation and coating method [39]. To maximize the tilt angle of the reflectors during the energy retrieval time, insulator cover and tiny, highly conductive particles are placed in the medium for storing energy [7]. Optimizing the angle and covering the top surface of the reflectors with an insulator cover will maximize the benefits of hemispherical solar desalination. In contrast to a conventional solar still, a unique desalination technique based on a quantum dots evaporator is suggested. This method increases the rate of evaporation from wastewater while boosting the distillate production by 27%. Solar radiation is absorbed by a glass matrix based on quantum dots [40]. In terms of boosting the thermosiphons’ uniform ability to collect solar energy along their peripheral, the integrated evacuated tube modified parabolic concentrator is shown to be useful, outperforming the classic vacuum tube applications by a large margin [6]. The silicon coating caused the glass cover’s condensation behavior to change from filmwise to dropwise, thereby increasing the coated glass solar still’s water yield by 15.6% over that of the bare glass solar still [41]. The development of a novel solar evaporator is described, which produced steam with a remarkable 99.99% salt removal efficiency [42]. A black receiver is designed with a finned system used for condensation, a manual tracking parabolic concentrator, and a main receiver to make up a solar thermal system [43]. The design and analysis of a low-temperature flash evaporation desalination system is examined, that would be run in batches without electricity and harness solar energy captured by flat-plate collectors [10].

The effective treatment of kitchen wastewater is suggested with reverse osmosis reject in a locally built, one-stage functional pyramid solar distillation unit [44] using glass beads coated in carbon nanomaterials as a medium for storing heat. For producing algae-based biodiesel, a parabolic trough collector is included into a solar-powered reactive distillation system [45]. More yearly cost savings are possible with this strategy than with the conventional approach. Using premeasured amounts of soil, sand, and paraffin wax as heat absorber materials, the increased capacity of a solar still is compared to that of a normal solar still [46]. A unique composite thermal energy storage device is made by combining paraffin wax and used cooking oil [12]. Experimental research is carried out on notable benefits, such as increased productivity, better thermal efficiency, and significant economic and environmental benefits. A single-slope small-scale distillation plant with a capacity of 100–400 L/day is examined for its technoeconomic viability in three different Indian climates: hot and dry, hot and humid, and composite [47]. The affordability and viability of a solar distillation system are also tested. At a concentration of 0.012%, Al–Cu nanoparticles can increase a conventional solar still’s energy efficiency by up to 64% [13]. With an increase in nanoparticle concentration, the efficiency rises and reaches saturation at a concentration of 0.0112%. The daily production of the solar still has grown due to the buildup of ceramic nanoparticles in the basin water [48]. The enhanced solar still has an efficiency of 34%, whereas the conventional still’s efficiency is 22%. It is discovered that design modifications result in a 54% increase in total efficacy. Twenty kilograms of aromatic crops are processed in batches using an updated solar-powered distillation apparatus and resistive heating components with controllers driven by solar PV panels [15]. Using closed mild steel tubes that were previously packed with carbon nanoparticles made from candle soot and paraffin wax (as a phase-transition material) increases the water output of the tubular solar still [16]. It is also discovered that this system’s great thermal performance greatly increased the water output. Two design changes, using a glass cover coated in nanosilicon with the reduced graphene oxide (rGO)-coated absorber and another absorber with black paint coating that contained 10 weight percent of rGO, are presented [35] for increased evaporation/condensation and freshwater yield. A traditional still without fins is contrasted to the experimental results of aluminum parabolic fins for energy absorption in a single-basin, double-slope solar still [17]. A novel solar-powered direct-contact membrane distillation module uses karanja seed oil, graphene oxide immobilized-lipase biocatalyst, and trans-esterification reaction biodiesel production from second-generation renewable carbon source to enable continuous separation and recycling of unreacted alcohol (>99% recovery) [18]. Productivity in a single-slope wick-type solar still increased when nickel oxide nanoparticles produced from Acalypha indica stem and leaf extract were introduced to the saline water in the water reservoir [19]. A solar distillation/cum-drying system with a parabolic reflector is incorporated into a tiered basin design [20]. It has been noted that at lower flow rates (50 ml/minute) than at higher water flow rates (65 ml/minute), the distillate yield is around 15% higher. The hybrid solar still that combines a vertical diffusion still and a basin solar still is found to perform better in the winter than in the summer [21]. The fermenter to a membrane distillation process is powered by the sun to separate and concentrate the ethanol produced during fermentation [49]. This technology ensured a higher ethanol flux (23 kg EtOH/m²/24 hour) compared to earlier research because it has a rectangular cross-flow module and counter-current hot and cold stream flow. An effective active solar distillation system consists of a solar still with a serpentine loop heat exchanger, an evacuated receiver tube, and a Fresnel lens concentrator [22]. The heat-transfer fluid in the solar collector loop is Al₂O₃–Therminol-55 nanofluid. The stepped-type basin still is designed for optimized output through integration with evacuated tube collectors and a stepped, tilted absorber with a triangular exposure area, thereby reducing maintenance requirements by mitigating the shadow effect [23]. A passive solar still system (Fig. 2) is constructed using copper cylinders containing phase-changing materials such as lauric acid, stearic acid, and paraffin wax [11]. Blackened jute cloth attached to a vertical rear wall and an angled basin liner in the still’s basin box boost the distillate yield (62%) of a solar still. Using the heat losses from the distillation unit’s basin, a drying chamber below a single-slope, single-basin solar distillation-cum-drying unit with parabolic reflector tries to dry ginger [50]. An experimental investigation on a basin-style solar still with a single vertical distillation cell and a tilting double-glass top aims to boost productivity [51]. The integrated solar distillation system with PV thermal compound parabolic concentrator collector is designed to be self-sufficient in meeting the daily needs for direct current (DC) electricity during daylight hours and potable water on a commercial level [52]. The use of cross-flow hydrophobic membranes made of polytetrafluoroethylene and polypropylene is investigated to remove arsenic from contaminated groundwater using solar-driven membrane distillation [53]. The next section reviews the distillation by solar technologies using solar still.

2.3 Research on solar still design

In order to address the issue of drinking water scarcity and waterborne illnesses in rural and isolated areas of poor countries, as well as to achieve the objective of sustainable development, solar stills [54, 55] are an affordable method of converting salty water into drinkable water using cleaner energy. To make the most productive and energy-efficient solar still designs commercially viable for both industrial and residential applications, experts have been studying them for many years. The several heat-transfer nanofluids (aqueous Al₂O₃, MgO, and GO) utilized in the pyramid sun still arrangement are compared, along with how they impact the solar still’s performance [56]. The passive and active solar stills are illustrated in the freshwater production with 41% improvement [57]. When the tube still and pentagonal pyramid still were tested using a thermal energy storage medium based on latent heat, it was discovered that the tubular still produced the best results out of the four configurations [24]. A new biomaterial made of conch shells is being investigated for use as a porous medium and energy storage material in solar stills, with the goal of outperforming traditional solar stills by 10.8% [25]. The double slope of a solar still produced a higher water yield when channel attachments were used, and it offered advice on how to address the issue of drinking water scarcity in hot climates [58]. With different TiO₂/jackfruit peel nanofluids colored with silver balls, the double-effect solar distiller’s performance and thermo–environment–economic analysis are shown [26].

A zigzag-shaped air-cooled condenser (Fig. 3) and cuprous oxide nanomaterial improve a solar still’s performance [59]. Using a hybrid solar still and forced convection (12 V DC fan), the effects of the thermal energy storage material (waste pieces of black granite) are investigated in connection to water desorbed from the weak liquid desiccant and distilled water output from the saline water [60]. It has been discovered that a closed-loop, inclined-wick solar still that has a water reservoir for extra heat storage produces more than a conventional inclined-wick sun still [61]. An air cavity connected to the sun still’s absorber plate is part of a redesigned design, and efforts are undertaken to determine the solar still’s feasibility from both a technological and financial standpoint [62]. A proposed experimental study examines the effects of water content on the efficiency and productivity of High Density Polyethylene (HDPE) solar stills with triangle and single slopes [63]. By employing sisal fibers to lower the glass cover temperature and increase productivity by roughly 19.1% relative, the energy-economic performance of the solar still is evaluated [64]. The main drawback of the solar still is the lower productivity compared to active desalination technologies. These systems can also be limited by the availability of solar radiation, especially during cloudy days. Hence bacteria are still prevalent in the distilled water, although exposed to sun without proper treatment. Photocatalytic treatment using membranes is effective in removing the harmful microorganisms, and active research on water treatment is discussed in the next section.

2.4 Water treatment from photo-assisted processes

The efficacy of disinfection, which is typically the last stage of water treatment, is crucial for maintaining public health. The most widely used techniques for disinfecting water nowadays are chlorination, ultraviolet (UV) irradiation, and ozone (O₃) release. Photocatalysis for water purification has drawn a lot of attention lately. Modern alternative technology called photocatalysis has many benefits, including operating at room temperature and atmospheric pressure, being inexpensive, producing no secondary waste, and being widely available and easily accessible. The commercial carbon powder’s photothermal characteristics is examined for solar thermal applications, and metal beads are employed as heat-storing materials to improve the evaporation process [44]. The photothermal effect of carbon nanoparticles is responsible for the higher rate of water evaporation (40%) observed in carbon-coated metal beads compared to plain metal beads (7%). Using life cycle assessment, the environmental effects of providing a family of six with enough safe drinking water over a 6-month period is compared for three treatment options: boiling, chlorination, and sun water disinfection with a transparent Jerrycan [65]. Paraquat-contaminated water is treated by photo-Fenton treatment, which used industrial waste containing Fe as a catalyst [66] using foundry sand, fly ash, blast sand, and red mud—industrially produced waste byproducts rich in iron as catalysts. The state of drinking water is discussed on solar thermal technologies that are being used to treat it for various types of distillation systems, particularly solar stills [67]. A straightforward GO/Ag₂O heterostructure is discovered that can be synthesized at room temperature and used for industrial waste management [68]. Because Ag₂O and GO charge very quickly, this combination produces a great deal of solar photocatalytic activity and reactive oxygen species (ROS) species that destroy bacterial colonies. It also produces more super oxide and hydroxide radicals.

The issues and challenges surrounding the use of the energy–water nexus to advancements in solar-powered water-purifying systems are investigated [69]. The process of creating a super-hydrophilic surface is outlined and interconnected pores in a porous carbon cake using a potato slice [70]. This system is a highly efficient and economical method of purifying brine water and evaporation-based high concentrated dye. With the help of the sun, the effects of the photo-Fenton process on the treatment of petrochemical waste water are investigated [14]. Under specific circumstances, the sun-assisted photo-Fenton process of treating petrochemical waste water operated at the pilot scale, the chemical oxygen demand (COD) percentage was lowered to around 68.67 ± 2.8% after 280 minutes. To easily create highly photoactive TiO₂ nanocomposites using just one alkoxide precursor for use in real-world, solar water treatment applications [71] are described and discovered that the catalyst under consideration might mark a major advancement in the field of photocatalytic solar water treatment. The use of carbon cloth and titanium nanorods are demonstrated to effectively remove dye molecules, such as rhodamine, from contaminated water [9] through the use of a solar-powered interfacial steam generation mechanism. The issue of catalyst recovery by using a pressurized ultrafiltration technique is reduced to immobilize the photocatalyst on a membrane’s surface [65] and discovered to be able to both break down and filter the contaminants at the same time. Using sunlight as the energy source, zinc oxide-mediated photocatalytic destruction of trace amounts of the petrochemical pollutant α-methylstyrene in water is examined [72]. This section detailed the various methods of producing clean water, and thereby the clean water is affordable by SDG #6. The next section discusses solar-assisted irrigation employing solar technologies.

3. Irrigation system from solar PV technology

In order to reduce GHG emissions from irrigated agriculture and to replace fossil fuels as a source of energy, solar-powered irrigation systems (SPIS) offer a clean technology option for irrigation. Pumps for the abstraction, lifting, and/or distribution of irrigation water [73–75] are run by electricity produced by solar PV panels in the SPIS. Applications for SPIS can be found at many different scales, ranging from massive irrigation schemes to individual or communal vegetable gardens. Research activities involving SPIS are described next.

Internet of Things (IoT) system (Fig. 4) is found to be robust and watertight, enabling its use in outdoor farming [76]. A solar power supply also reduces sensor node maintenance and does away with the requirement for cabling. The utility grid is provided with day-round support from the adaptable and dependable microcontroller-based system [77], ensuring that the pump will be automatically protected from dry running, frequent voltage fluctuations under-voltage, and overvoltage.

The water pumps powered by electricity, fuel, and solar PV [78] are evaluated on technoeconomic and environmental implications for Assam, India’s sustainable irrigation with elements, such as the availability of groundwater, crop rotation, and energy costs. The goal of the technoeconomic study is to identify the lowest cost estimate based on data processing and analysis at different stages of development for water requirements and horticultural crop cycles, as well as energy cost savings and grid energy dependability [36].

The use of IoT sensors to manage and monitor intelligent solar irrigation systems is involved with a Global Positioning System [79] for crop production, and an intelligent agriculture management system to produce benefits for agriculture. This design met all of its water use objectives, and overall running costs decreased labor, energy consumption, and productivity. The solar panel, tracking to effectively charge the battery [71], and conversion of DC to alternating current (AC) power the agricultural motor equipped with the timer [80]. It has been determined via experimental observations that a solar PV pumping system of capacity 1 hp [81], either AC or DC type, could be used to operate mini-sprinklers with success. This finding provides a workable solution for marginal and low-income farmers facing a situation of water scarcity in the near future, as well as a way to lessen climate change’s impacts on agricultural farms. The solar-powered water pumping system is investigated using a quadratic boost converter [82], and the outcome was a significant reduction in power consumption quickly. A low-cost solar-powered [83] pumping system is integrated with a gravity-fed-type micro-irrigation system to distribute emitter discharge evenly throughout the tiny 18 m × 6 m plot, and the flow rate variation was found to be satisfactory. The comparison of solar-powered irrigation facilities in India is listed in Table 2. Once the agriculture produce is collected, the next process begins by drying the bulk amount of agricultural products. Solar-based drying systems are proved to be effective, and its research studies are explained in the next section.

4. Solar-based drying systems

Drying extends the shelf life of many food items, including pickles, chillies, amlas, seafood, fruits, and spices. Food products can be made dry by using a process called drying, which also stops microorganisms like yeast and bacteria from growing and causing other moisture-related reactions. Food items that have been dried are likewise more environmentally friendly. There are several ways to dry materials: using the sun directly, using an electrical dryer that burns biomass, and using solar dryers. Solar dryers require less maintenance and have a longer lifespan of 15–20 years [84–89]. One device, or multiple equipment, such as a drying chamber and a flat-plate air heater, are used for the collection and drying of solar energy. This section presents recent research works on solar dryers.

The solar drying method uses indirect solar radiation as opposed to sun drying, which involves directly exposing food to the sun. The basic idea behind solar drying technology is to harness solar energy by heating the air inside solar collectors and then transfer that heated air into the drying chamber, which holds the products that need to be dried. Table 3 compares the various design and applications of solar dryers in India. This mixed-mode natural convection UV tent house solar drier [104] is designed to dry potato slices and includes a solar flat-plate collector. For potato slices that are 2.5 and 5.0 mm thick, the initial moisture content value of 85.25% decreases to 14.75% during drying by natural convection. With the 2.5-mm-thick potato slices, all of the drying kinetics are excellent. The airflow, temperature profile, and heat transfer of pineapple slices during solar drying for mixed-mode solar dryers integrated with flat-plate and finned collectors made of baffles and semicircular loops are investigated using three-dimensional computer models [90]. The dryer’s nonhomogeneous temperature distribution is investigated, and the finned collector offered a more efficient air distribution system. Using an induced-type solar dryer, the drying kinetics, thermal, and morphological analyses of food material are examined [91]. It is discovered that spherical-shaped samples provide intriguing findings and possess the ability to reach the maximum temperature because of their tiny surface area. Investigations are conducted into the quality attributes, drying kinetics, thermal profile, and parameters related to mass transfer of pineapple slices that are dried by PCM-assisted drying, sun drying by infrared, and direct drying [92]. Slices of pineapple that were hybrid solar-dried with infrared assistance demonstrated superior quality and a better drying procedure. The effectiveness of refrigeration adsorption dehumidified dryers is investigated in order to assess the functional group changes, morphological changes, and variations in the essential oil composition of cardamom. It is discovered that this method of drying is more effective than other traditional methods and shows promise as a replacement for fluidized bed dryers [93]. To dry shrimp even when the sun is not shining, an energy-efficient solar hybrid drier with a biomass gasifier, heat-transfer fluid, and sensible heat storage material (HSM) is created. The hybrid mode of operation is very cost-effective and has the shortest payback period, according to the economic study [94]. The usefulness of an indirect PV-T mode sun dryer in drying neem leaves for a year in a range of weather conditions is investigated in an experimental setting. The results of the quality standards showed that measuring antioxidant activity, total color change, total phenolic content, and total flavonoid content had no effect on the drying product quality [95]. The solar dryers that integrated thermal energy storage and several types of paraffin wax are analyzed [96]. Many sun dryers are examined for their thermal properties, both with and without paraffin wax. In solar dryers, a 2:1 mixture of paraffin, n-docosane, and kerosene boosted the thermal efficiency by as much as 50%. A comprehensive classification and comparative analysis of solar dryers (Fig. 5) with energy storage derived from renewable sources is presented [105]. The results of the study indicate that the most effective means of extending the shelf life of agricultural products while reducing energy consumption and protecting the environment are solar drying techniques paired with natural materials thermal energy storage devices.

For the indirect form of drying tomato flakes, the thermal, environmental, economical, and quality factors of a domestic hybrid solar drier [97] are evaluated. The results demonstrate that this method can reduce GHG emissions, save energy consumption, and improve the quality of dried commodities, making it a viable option for small-scale farmers as well as residential users. An evacuated tube solar dryer is used to assess the dryer’s thermal performance as well as the drying characteristics and quality features of pretreated (control, peeled, and cured sample) turmeric slices [98] with and without thermal energy storage. It was discovered that the cured turmeric sample, which was dried by pretreatment, retained the highest curcumin content. The usefulness of a cabinet-style solar dryer [99] is assessed with naturally occurring convection drying exclusively for Indian gooseberries. A higher-temperature passive sun drier makes it possible to remove moisture more quickly. The solar conduction dryer [106] is discovered to be more effective in terms of drying time, drying rate, and thermal efficiency when compared to other conventional sun dryers based on convection mode. A cost estimate indicates that the money invested in manufacturing this dryer may be recovered in 1.02 years.

For the purpose of drying agricultural produce, the creation, performance assessment, and economic analysis of a solar bubble drier [100] are contrasted with a sun tunnel dryer. The drying rate varied between 0.081 and 0.006 g of water evaporated per gram of dry matter per hour when using a sun bubble drier and between 0.014 and 0.007 g when utilizing solar tunnel dryers. For the purpose of drying apples, a solar dryer with benzoic acid and thermominol-55 heat storage mediums is built [107] using evacuated tubes and a thermal storage unitary heat pipe solar collector. The maximum energy of benzoic acid was 3069 kJ, while the maximum energy of therminol-55 was 1881 kJ. Using Therminol-55, the drying process functioned effectively. The performance analysis of a solar dryer based on the temperature, relative humidity, and moisture content (%) of onions and garlic [108] was conducted. It was discovered that the solar dryer is more effective than open sun drying. Two experimental setups are used to investigate the kinetics of drying carrots and the efficacy of indirect passive sun dryers [101] ensuring the accuracy of the findings. The energy and exergy studies are compared for forced convection and indirect natural solar dryers [102] by installing a diverging tunnel at the collector’s intake that is integrated with DC fans and powered by solar panels. The economic benefit of HSM in the solar drying of untreated Carica papaya slices is demonstrated by a hybrid PV–thermal solar drier based on evacuated tube collectors [103]. This technique significantly shortens the drying time while increasing the drying potential. When compared to sun-dried papaya and sun-dried papaya in dryers without HSM, the results demonstrated that solar-dried papaya in dryers with HSM is seen to be better conserved without losing size, shape, color, appearance, texture, flavor, and quality. Process heating in chemical or food processing industries typically involve large volume of water at higher ambient temperatures. This cannot be achieved by solar dryers alone but can be effectively handled by solar heating systems. The next section deals with the different solar heating systems under progressive improvement in design and performance.

5. Solar-based heating systems

Using sunlight to heat water or air in a structure is known as solar heating [109–111]. Passive and active solar heating are the two types available. The architecture of a structure is a factor in passive heating. It is possible to reduce or even completely eliminate the need for fuel by optimizing the building’s materials, construction, and site placement to optimize the heating effect of the sun hitting it. In order to provide hot water or space heating, active heating uses mechanical methods to store, gather, and transfer solar energy within structures. Heat is produced by sunlight striking a building’s collector array. This heat is then transported to a carrier fluid typically a liquid, but less frequently air, and pumped to a system for conversion, storage, and distribution. Water, or less frequently glycol, is pushed via tubes in contact with a flat-plate collector in liquid-based systems. Various improvements are made in solar heating research and discussed here.

A direct-expansion heat pump powered by solar and air [112] is discovered and advised for use in hot climates to quickly and efficiently heat water. Compact concrete absorbers intended to heat water are explored in relation to the usage of solar energy in spiral tube arrangement; it was discovered that these absorbers were more cost-effective than traditional solar flat-plate collectors [113]. Using a hybrid multicriteria decision-making method, novel designs and distinctive heat-transfer processes are investigated to increase the efficiency of solar water heating systems [114]. Installing a solar heating device [115] that would warm entering ambient air before it was pumped into the region that needed ventilation using a conjugate heat-transfer system would improve a wind tower’s year-round performance. An experimental study demonstrates that the indoor temperature can vary by 2°C–4°C, guaranteeing the best possible thermal comfort. An insightful information is provided that helped researchers, engineers, and architects create and improve heating and ventilation systems, opening the door to more cosy and ecologically friendly living spaces [116]. Glycerin is used as a cooking load in a dual-purpose solar concentrating cooker; its design and thermal performance are discussed [117]. It also suggests a novel, inexpensive 2-fold reusable system that effectively handles simultaneous water heating and cooking. An economical solution is focused for solar air heating [67] with low-cost PCMs, paraffin wax, and coconut oil. To determine the potential application of solar-assisted ground source heat pump systems [104], in-depth research is conducted for space heating and cooling applications, which led to energy savings of 151.77 GW for space heating applications and 88.39 GW for cooling applications.

Energy-efficient renewable energy solutions are discovered by applying the Naïve Bayes classifier to categorize the input data and construct a sustainable environment [118] through a range of tests. In a hybrid solar collector, air flow residence duration is extended by the use of serpentine copper tubes for water and baffles [119] and discovered to offer more financial and ecological advantages than the traditional collector with quicker payback times. In order to maintain the comfort levels, experimental findings for employing PCMs of necessary type and quantity with transition temperatures of 22°C, 29°C, and 34°C are reviewed [120]. As a backup water heating system, a solar-powered heat pump (Fig. 6) is used [121], utilizing the solar collector efficiency and COP to evaluate the system’s performance parameters. For the solar air heater, the perforated delta-shaped winglets situated on the absorber plate are optimized with respect to their spacer length parameter [122], and it was discovered that a solar air heater with a smooth absorber plate performed 5.17 times better. The flat-plate collector with bent tubes [123] is suggested, with a maximum thermal efficiency estimated to be 71%. This process is believed to be a substitute for growing thermophilic bacteria during the process of anaerobic digestion, which generates biogas. In a solar water heating system, barriers shaped like a delta are effective [114]. A single-pass solar air heating system’s efficiency is empirically analyzed and provided [124], employing a phase-changing substance based on paraffin as a means of storing energy during the day. The thermal performance of a solar air heater [125] is examined using a parabolic trough and a U-shaped heat exchanger. It has been discovered that using a copper heat exchanger instead of an aluminum one boosts the solar air heater’s efficiency by 9.29% at high flow rates. However, at higher temperatures, the aluminum heat exchanger performs better as a percentage of the solar air heater. The largest thermal amplification of Nusselt number is caused by noncircular holes in perforated copper strips with delta-winglets, and this affects the thermo-hydraulic performance of the absorber tube of the solar water heating system [114]. The impact of concentrated inorganic and organic nanofluids (water, chitosan, and Al₂O₃) is assessed on the solar water heating system’s thermal performance [126]. Chitosan and Al₂O₃ nanofluids showed experimental efficiencies of 33.60% and 26.10% higher than water as the working fluid, respectively. The outcomes were compared with theoretical values calculated in accordance with American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standard 93-2003. Thermal conductivity and rapid thermal charging properties are demonstrated in the synthesized organic PCM nanocomposite, which was made up of a combination of two organic eutectic gel and a small quantity of nanographite as a supporting material [127]. They discovered this could be used to supply hot water through the use of a solar-powered water heating device made locally and a solar-powered, quickly warming glove. A theoretical investigation into the performance of an extruded finned plate air heating solar collector [128] for rice drying applications finds that finned plate air heating solar collectors with 80 fins, 0.6 height-to-duct length ratio, and 2 mm fin thickness perform best in Guwahati weather conditions. By combining the system with a solar air heating duct, the poor heating potential of earth air heat exchanger systems can be increased [129]. When the experiments are carried out in the winter, the results from the experiment data are found to be in good agreement with simulated results within a variance of up to 7.9%. The findings of an initial evaluation are provided in relation to the possible estimation of solar process heating [130] in the paper industry using solar collectors to provide heat at the necessary temperature range of 320–2770 K. They discovered that the annual process heating potential at 43 PJ can be increased by employing agricultural leftovers and recycled fibers as raw material. Comparison of solar heaters and applications among the literature are made with respect to location, design, and application with remarks in Table 4. Apart from the heating solutions, essential to cold winter homes, solar power plants are crucial in providing/distributing electricity to rural homes. The technology in generating power by solar means is described next.

6. Power production from solar technologies

Solar energy systems [131] generate electricity by utilizing the energy of solar irradiation. Presently, PV, concentrated solar power (CSP) and biomass using solar technologies are addressed here. Through the photoelectric effect, PV cells produce energy by utilizing the conducting properties of specific substances, most notably silicon. In order to create steam that runs a thermal electric plant, CSP uses reflectors to concentrate sunlight on a tiny area.

6.1 CSP system

Large power plants gather solar heat by installing flat or curved mirrors across sizable surfaces. Countries with abundant sunshine, such desert regions, are the best places for this technology. This method uses collectors [132] to heat a transfer fluid (such as gas, oil, or molten salt) to a high temperature while concentrating the heat from the sun. By heating a network of water, the fluid creates steam, which powers a turbine using mechanical energy to produce electricity. Research involves the thermal storage processes, heat-transfer fluids, and chimney design, etc.

The linked system including a low-temperature metal hydride (LaNi₅-based alloys) and a high temperature metal hydride bed (Mg–LaNi₅) for thermochemical energy storage in CSP plants is investigated [133]. The performance of the system is examined in relation to temperature variations in the heat source, regeneration, and ambient domains. Utilizing local metrological data, the cogency of a dry-cooled CSP station [134] is assessed to determine its likelihood of accretion for generating more net power compared to a wet-cooled plant at Jodhpur and Leh, India. It has been observed that, especially during the summer when Leh has exceptionally low temperatures, dry cooling has boosted turbine efficiency. Power generation is shown to be boosted by up to around 80% when using a ground surface with stair shape in a chimney-based solar thermal power plant [135] as opposed to a absorber surface at flat ground. Melted salt used as a thermal energy fluid, the Rankine cycle, and a solar field with parabolic troughs are the three environments in which the performance of thermal and hydrogen energy storage devices is investigated [136]. The outcomes demonstrated that because the hydrogen system required more energy conversion stages than the thermal system, it performs worse. The solar power plant of concentrated type uses a diphenyl ether heat-transfer fluid and a perhydro dibenzyl toluene dehydrogenation reactor [137]. The counter-current mode of operation offers the lowest process total annual cost, with 623 K for the intake feed temperature and 673 K for the thermic fluid entrance to the jacket. Potential locations for floating solar power plant installations [138] are investigated, and the Ladakh region’s capacity for energy production is estimated. Considering the selling of energy, carbon credits, and the levelized electricity cost, an economic evaluation of a large-scale solar updraft tower power plant examines the best cost of electricity generation and revenue analysis [139]. In order to create more complex renewable energy-based power production systems and meet net-zero carbon emissions requirements, the possibility of lowering the height of a highly effective divergent chimney [140] that produces power equivalent to that of a long, unstable, expensive traditional cylindrical chimney is explored. The solar power plants are located at various places in India, and they are listed against the power generation types with specific remarks in Table 5.

The technoeconomics of central tower receiver, parabolic trough collector, and wet- and dry-cooled condenser cooling technologies are evaluated in relation to the impact of hours of thermal energy storage and nominal capacity [142]. For the purpose of producing greener energy, it is advised to build a massive solar chimney power plant using a divergent chimney and a semi-convergent collector [149]. According to observations, dry-cooled solar power tower plants [150] can produce up to 4.5% more electricity annually, and their levelized cost of electricity is also expected to be 13% less than that of wet-cooled Parabolic Trough Solar Collector (PTSC)-based facilities (Fig. 7). Although CSP is effective in solar active regions, the electricity production by solar PV systems is efficient in diffused sun light also. Hence the next section reviews the advancement in solar PV systems in the recent period.

6.2 Solar PV system

Light is converted to electricity using the PV effect. Edmond Becquerel, a French physicist, made the discovery in 1839, and industrial use of it began in 1954. Practically speaking, a semiconductor transforms light that strikes it into electricity. Multiple cells that produce DC are assembled into a solar panel, and an inverter transforms that electricity into another form. The panels of modules can be employed in both large and small systems and factories. Many research activities were started earlier and reported in Bhargava [151], Kaushika and Rai [152], Moharil and Kulkarni [153], Singh and Singh [154], and Tripathi et al. [155]. One such example includes a thorough description of the planning and development of Rewa ultra mega solar park [147], which provides an overview of the typical dangers connected to major renewable energy projects. Several solar PV tree models [156] are simulated, and the findings indicate that comparatively less area is required to generate the same amount of energy as typical plants (Fig. 8). A 5 MW grid-connected crystalline silicon solar PV power plant’s technoeconomic study, deterioration analysis, and performance evaluation are offered from 2013 to 2019 [157]. Performance indices including capacity utilization factor, PV system efficiency, monthly mean reference yield, final yield, and performance ratio were calculated. When compared to the standard design, the air velocity can be enhanced by about 270% by adding an effective bell-mouth at the intake and making the appropriate design changes to the collector and chimney [158]. The turbine’s power output will rise dramatically as a result. Based on the useful insights into the feasibility research, an investigation and recommendation are made about the exergy, energy, environmental, economical, exergoeconomic, energoeconomic, and enviroeconomic (7E) performance of solar PV power plant [130] on the grounds of seven Indian airports [148]. A CSP plant’s shell radius or length can be extended to enhance the system’s useful charging and discharging period [159]. Then, designs were optimized using the response surface methodology to achieve maximum discharging and charging times as well as good performance levels. Concentrating solar power facilities using parabolic trough collectors have higher unit capital costs [150] as compared to solar power tower with  thermal energy storage.

Using locally accessible materials and efficient calculations, a small-scale solar chimney power plant [143] is built. The finned multitube shell and tube latent heat thermal energy storage system is considered in relation to the dynamic performance of the Rankine cycle-based solar thermal power plant [160]. The optimal fin count and fin thickness for best discharge efficiency are also determined by this approach. Researchers discovered that 80% of the collector area measured from the chimney axis was the ideal location for cooling the PV module since it consistently provided a temperature decrease of 10°C–12°C. The feasibility of using a PV module into a hybrid solar chimney power plant was evaluated using these data [161]. By identifying barriers to its acceptance [162] and proposing methods to solve the primary barriers with the installation of solar power in electricity generating utilities, the use of solar electricity in thermal power plants is examined. Solar PV power plants use drones [163]. It is investigated to understand the importance of drone automation and intelligence in the active surveillance and data logging. A latent heat thermal energy storage system is combined with the development of a dynamic model for an organic Rankine cycle solar thermal power plant to increase the amount of electricity generated after dusk [144]. The energy consumption of the garment zone is computed using a 2.5 MW solar PV power plant [145], and the rates of return for the plant’s on-site and off-site locations are compared. By doing a performance analysis of a 190 kWp solar PV power plant [146] and comparing the findings with systems deployed internationally, the long-term performance under genuine operating conditions is investigated. When the execution of ground-mounted and rooftop solar power plants [141] in Assam, India, is compared, it is found that rooftop solar power plants not only function well but also save businesses money on electricity while promoting sustainability. Using long short-term memory (LSTM) and back propagation neural network (BPNN) models, it is possible to forecast the output of a solar PV power plant [164], and the results are almost in line with actual power production.

6.3 Solar biomass power plant

For heating, biomass power plants require enormous amounts of fuel feed, which might not always be accessible. In order to generate steam for electricity, heating with solar parabolic collectors and biomass combustion have been set up in simultaneously. The turbine inlet conditions (temperature and pressure) and variations in solar energy sharing have been taken into consideration when developing the hybrid power plant’s performance characteristics. Earlier studies were reported by Ahmad et al. [165] and Gabhane et al. [166]. A trigeneration system [167] is created with an emphasis on dairy applications that can produce green hydrogen, generate power, and cool at the same time. The technology produces a dynamic energy solution for the chosen communities by utilizing biomass from copious cotton waste during the night and harnessing solar electricity during the day. The numerous uses of solar PV [168] and thermal energy are examined in a range of thermochemical processes, including gasification, hydrothermal liquefaction, and solar pyrolysis. The bioprocess industry has also taken a cursory look at the integration of all three processes into a solar-powered biorefinery.

The efficiency of both solar- and biomass-based technologies in terms of total heat and power is examined both individually and in combination. The hybrid solar–biomass system [169] was determined to be a tried-and-true method of boosting solar energy conversion into fuel, lowering direct biomass burning, and eventually lowering GHG emissions. According to the technoeconomic feasibility analysis of solar biomass systems [170], hybrid systems that use renewable electricity sources are more effective at generating energy. An indirect active solar–biomass hybrid dryer [171] was developed to study the mathematical modeling, kinetics of drying, and quality of dried small cardamom. Color analysis showed that the green color retention was better compared to the drying process using biomass alone. The coproduction of potassic fertilizer from residual ash and concentrated solar-steam gasification (Fig. 9) is examined from a cost-benefit perspective [172] of biomass derived from empty cotton bolls. When compared to traditional fossil fuels, the solar-steam gasification of biomass from empty cotton bolls has the potential to reduce CO₂ emissions by 86%. In order to arrive at a sustainable solution, a thermodynamic modeling is offered for sizing a Rankine cycle-based solar–biomass hybrid power plant [173]. This model makes use of biomass system with fluidized bed combustion technology and parabolic trough technology.

In the discussion of the renewable hybrid power generating system [174], the technical and financial potential of the solar PV–biomass–biogas hybrid system is taken into account. The whole output of the polygeneration hybrid solar and biomass system, as well as its energy, energy efficiency, economic study, and optimization with objective functions of efficiency, are examined [175]. In a hybrid solar–biomass system, the simultaneous production of power, multieffect humidification, vapor absorption refrigeration (VAR), chilling, and dehumidification desalination system from different heat sources [176] are presented as ways to lower carbon dioxide emissions. The impact of various operating parameters, such as condenser pressure, boiler pressure, and turbine inlet temperatures, on the energy output and energy efficiency of the combined biomass–solar power plants is investigated, along with the state-by-state availability of biomass resources and solar direct normal irradiance [177]. In order to produce steam for power generation, accomplish multieffect dehumidification with a limited amount of heat from water vapor, and provide cooling using VAR (LiBr–H₂O) system in accordance with requirement of demand load, a feasibility study on biomass and solar power is carried out [178]. The biomass combustion creates pollution due to the fuel combustion in closed system. The pollution norms as per SDG are required to be met in an industry. The carbon capture systems are effective with the help of solar-assisted technologies, and it is discussed in the next section.

7. Solar-powered carbon capture systems

Due to the threat posed by global warming, there has been a rise in interest in using green energy sources in an effort to avoid or use fossil fuels as little as possible in recent years. One sustainable carbon source that is gaining traction is direct air capture. When fuels burn, fossil CO₂ is produced and trapped, resulting in calcine carbonates that are difficult to decarbonize because of the high temperatures needed. Solid sorbent and liquid solvent are the two direct air capture technologies that are most developed. The integration of solar thermal energy and the methods of integration, as well as the advantages and disadvantages in terms of economic and environmental effects, are all covered in relation to energy penalty and various postcombustion processes [36]. There is a discussion of the widely used methods using GO as adsorbent for capturing carbon dioxide by solar-assisted methods [179], including membrane separation, adsorption, absorption, cryogenic separation, and micro-algal bio-fixation. The effects of temperature, adsorption thermodynamics, mass of adsorbent, and CO₂ concentration were all examined. An energy-efficient penalization method was used for a solar-based carbon capture process after combustion, utilizing cryogenic technology [180], and the system can create high-purity CO₂ with minimum secondary emissions. As part of the performance analysis, the CO₂ recovery rate and purity are also altered.

In order to desorb the CO₂ gas directly within the solar collector tubes, a solar collector field pipe network is used in place of the conventional stripper unit in a novel idea of solar-powered solvent-based postcombustion carbon capture [181]. In a different study, methanol synthesis and hydrogen generating units are combined into a multigeneration system that uses solar heat. This system’s energy efficiency is 10% higher than that of the reference system [182]. Furthermore, around 43% of carbon dioxide is retained as methanol without compromising the efficiency of system elements. The system’s energy consumption is among the lowest of all documented CO₂ capture systems due to the requirement for adsorption and desorption using solar radiation [183].

More than 90% of the CO₂ emissions from a cement factory might be decreased by integrating a solar-driven calcium looping system. A heliostat field provides the entire amount of energy needed for the CO₂ sorbent regeneration process [184]. Lean vapor compression, solvent split flow, rich solvent recycle, and intercooled absorber, in addition to their combinations [185], were carefully modified to drastically lower the reboiler’s energy consumption from 11.1 GJ/ton CO₂ to 3.27 GJ/ton CO₂ using diglycolamine solvent in an exergy-based assessment [186]. High photothermal conversion materials were added to the eutectic nanofluid solvents in a solar-powered CO₂ capture system to raise the system’s temperature, which aided in the desorption process and encouraged the CO₂ absorption–desorption cycle with graphene [187].

An ideal method is presented with two solvent tank systems to capture 1.57 million tons of CO₂ annually with 28 % of the total solar energy. Desalination was the process that used the remaining energy to create 9.4 GL of fresh water annually [188]. Succulents are used as precursors in solar-driven temperature swing adsorption to create an adsorbent with a high CO₂ adsorption capability. Succulents have a large specific surface area and high sun absorption [189]. In order to offset the energy loss from absorbent regeneration in coal-fired plants, amine-based carbon capture systems are being researched in conjunction with solar thermal subsystems. The effects of changing solar heat and reboiler operating temperature on absorbent regeneration performance were investigated [190].

8. Future prospects in solar energy

In light of the pressing global need to address climate change, India’s solar energy industry serves as a ray of hope and a living example of the potential of sustainable innovation. India has a clear geographical edge. Effective energy storage technologies are becoming increasingly important as renewable energy sources continue to gain popularity. Decentralized solar power systems promote energy independence and resilience by enabling users to produce, store, and exchange energy locally. Artificial intelligence (AI) integration has the potential to completely transform solar energy management. AI algorithms are being used to improve system efficiency, forecast energy production, and position solar panels optimally. Solar technology helps Indian farmers become independent in terms of electricity. It assists them in moving away from diesel and toward solar pumps. This results in farming that is both more economical and cleaner. Significant technological developments are taking place in the solar business, with the potential to increase the efficiency and accessibility of solar energy. With an average solar radiation of 4–7 kWh/m³/day and roughly 300 bright days per year, India has some of the world’s highest solar potential. To understand the scenario, over 1000 GW of power could be produced if solar panels were installed on just 1% of India’s land area at an efficiency of 15%. The Indian Solar Rooftop Scheme provides financial assistance to residential families for the installation of grid-connected rooftop solar systems on about 10 million residences. This initiative enables customers to lower their power costs during solar energy periods and generate revenue by selling excess units to the grid. This program provides employment possibilities to empower people. Some of the prospects in solar energy technologies are listed next.

There is a lot of promise for applying machine learning algorithms to anticipate solar power in a variety of real-world circumstances. One real-world use is improving the efficiency of solar power plants, where operators may more effectively manage the production and distribution of electricity by using precise forecasting and prediction models that take into account changing climatic conditions [54].

Since 2D nanomaterials have distinct electrical properties and an atomically thin structure, using them in solar PV cells can significantly improve light absorption and charge transport qualities. Examples of these nanomaterials include graphene, phosphorene, and MXene. The drawbacks of conventional materials, such as their bulkiness, scalability, complicated manufacturing processes, and reliance on poisonous or rare ingredients, are all eliminated by 2D materials [191]. There are a lot of potential and obstacles associated with integrating 2D materials into solar cells. For 2D material-based solar cells to become more widely used in practice, these issues must be recognized and resolved.

To enhance the efficiency of solar stills and increase freshwater yield, researchers have investigated the use of magnets. Significantly, there has also been a decrease in the environmental impact (up to 71.1%) and production costs (up to 42.6%). In order to fully understand the impact of magnet forms, future research should investigate other magnet shapes with comparable sizes [192].

One solution to address issues like unequal cooling of the solar module and refrigerant leakage was to identify the heat pipe-based PV/thermal system (solar-assisted heat pump system). In particular, on days with little sun irradiation, more investigation is needed to function as a dependable supply of hot water [193].

In an irrigation system, the combination of a sprinkler and economical, eco-friendly PV technology reduces the amount of water and electricity used [194].

Nanofluid-seeded direct absorption solar collectors that use plasmonic nanofluids—colloids containing plasmonic nanoparticles such as Au, Ag, Cu, Al, etc. in base fluids—have emerged as viable thermal media for efficient solar energy conversion. Research on photothermal conversion potentials and high thermal gain can be compared to other kinds of nanofluids [18].

9. Conclusion

In this review, solar-assisted technologies formulated by researchers in every field have been explained briefly. However, there are many articles to be reviewed, and only a comprehensive information is provided here. The comparison on water yield by desalination and distillation using solar still designs has been tabulated along with economic analysis and relevant technology employed in the process. Similarly, other technologies such as irrigation, heating, drying, and power generation are also explained in this study. These technologies are meant for implementing the sustainable development goals from the United Nations in order to save the humanity from climate crisis and environmental disasters.

India stands fourth globally in solar power capacity as per Renewables 2022 Global Status Report. According to the Ministry of New and Renewable Energy’s annual report, which was released by the Indian government on 31 December 2022, India’s installed solar power capacity is 63.30 GW, with 51.13 GW under implementation and 20.34 GW under tendered category, for a total of 134.77 GW. Access to sustainable energy for rural livelihoods is the main aim of solar energy initiatives. The future is predicated on the idea that a number of vital rural livelihoods, including fisheries, poultry, dairy, horticulture, animal husbandry, and other village industries, cannot flourish in the absence of reasonably priced and consistent electricity. Decentralized renewable energy is anticipated to stimulate rural livelihood initiatives aimed at lowering poverty, creating jobs, and enhancing rural residents’ quality of life in electrical, thermal, and mechanical applications. Gobardhan was started with the goal of ensuring village cleanliness by using the process of biomethanation to turn bio waste—including market garbage, agricultural residue, kitchen scraps, and waste from cattle—into biogas and biofertilizers. Anaerobic conditions are used in the biomethanation process to transform organic waste into biogas and bioslurry. According to this approach, businesses such as cooperatives, dairies, entrepreneurs, and others can establish sizable biogas/compressed biogas plants to generate gas on a commercial basis. Fuel dispensing units, industries, and oil marketing companies are among the direct markets for the compressed biogas. The plant’s slurry can be processed into organic manure and solid and liquid biofertilizers.

Reducing GHG emissions is one of the mission’s main objectives, and it will be accomplished by increasing the use of clean, inexpensive, and renewable energy for productive purposes in rural areas. A number of technologies are suggested, including solar-powered lighting and ventilation systems for backyard poultry farms, solar-powered milk chilling systems at milk collection centers, solar-powered small cold rooms and fish dryers for drying spices, vegetables, and fruits (horticulture), solar-powered aerators and fish dryers, and solar-powered lighting and equipment at communal facility centers for artisans.

Offering energy access options in rural and isolated locations is the main goal of the national solar mission’s off-grid and decentralized solar PV application programs. Major emphasis was placed on significant applications, particularly those related to rural development, during the program’s Phases I and II. Examples of these include solar lighting, mini/microgrids, solar study lamps for students, and solar water pumps for irrigation and drinking water facilities. With better technology and lower costs thanks to creative procurement techniques, Phase III of the Off-grid and Decentralized Solar Photovoltaic Applications initiative is being developed based on the experience obtained during Phase I and II. Future research in this expanding topic may examine the possible advantages of solar technologies. Researchers might broaden their examination to examine the sustainability gap by pursuing the opportunities and potential presented in this study.

Author contributions

R. Manimaran (Formal analysis [equal], Investigation [equal], Resources [equal], Software [equal], Writing—original draft [equal], Writing—review & editing [equal])

Conflict of interest statement

None declared.

Data availability

The data that support the findings of this study are available from the corresponding author, upon reasonable request.

References