Search

Graphical abstract Highlights • SOLWAT was subjected under a microbial kinetic study to apply system optimizations. • Photovoltaic performance and E. coli , Enterococcus spp. and C. perfringens response was studied. • Faecal indicators were total inactivated after 3 h reducing by half the treatment time of conventional SODIS reactors. • SOLWAT power output could be benefited from lower operational temperatures when using reduced treatments times. • The water disinfection reactor located above the PV module did not affect the final energy output. Abstract The SOLWAT system, integrating the functions of photovoltaic electricity generation and solar disinfection, was subjected under a microbial kinetic study with the aim of applying system optimizations. E. coli , total coliforms, Enterococcus spp. and Clostridium perfringens response and photovoltaic performance vs. conventional PET bottles was studied using river water sources and natural sunlight. Results showed that under strong climatic conditions the time required for the solar disinfection could be reduced by half in the SOLWAT system (3 h), increasing the quantity of treated water and favouring the SOLWAT power output due to the cooling effect of the water being purified on the top of the PV module, which is maximum during the beginning of the SODIS process, so the module could be benefited from lower operational temperatures when using reduced treatments times. [ABSTRACT FROM AUTHOR]

Energy access at refugee camps is one of the main challenges to address in humanitarian response actions, especially on long-term situations. The lack of access to electricity depends, among other factors, on the local natural resources and available technologies. In this sense, solar photovoltaic is one of the most appropriate technologies, especially now with the decrease of the photovoltaic costs. But long-term performance, reliability and social acceptance must be ensured to facilitate the introduction of the technology and its rapid widespread in these humanitarian context. This work presents the results of a field study conducted at the Saharawi refugee camps, inspecting the photovoltaic systems installed in the health institutions after 10 years of use. Results show how despite the good initial system design and high quality of the PV components, the lack of training on operation and maintenance of the PV installations have led to a dramatic reduction of the lifetime of the systems. Strong training programs on basic photovoltaic concepts and operation and maintenance of systems are required to solve this problem and guarantee the long-term functioning of the installations. [ABSTRACT FROM AUTHOR]

Two hybrid SolWat systems operating in static (without flow circulation) versus dynamic (with flow circulation) mode were simultaneously compared. This work aims to demonstrate the viability of SolWat in dynamic mode to: a) adapt to the operation of the WWTP with a continuous flow, in which the wastewater flows continuously for treatment, b) treat a larger volume of water in the system and c) increase the cooling of the PV modules thanks to the cooling of the temperature of the water sample to improve the energy efficiency in the system. Real secondary wastewater effluents from wastewater treatment plants were used, using solar energy for water disinfection and photovoltaic energy production, in order to use the SolWat systems and implement it as a tertiary treatment. A total of five experiments were performed during autumn, winter, spring and summer. Solar disinfection of Escherichia coli , Enterococcus faecalis and Clostridium perfringens was assessed, and physicochemical parameters were also analysed. The UV dose received by the SolWat systems was the same, but not for the microorganisms in the water sample. The static SolWat irradiated a particle (microorganism) for 4 h, while the dynamic SolWat irradiated intermittently, so the latter system received a shorter UV exposure time, and therefore a lower UV dose. Results indicated that, although the microorganisms did not obtain the absolute bacterial inactivation during the SODIS treatment in any SolWat system, adequate inactivation levels were achieved to allow the reuse of the water for various uses (Royal Decree 1620/2007, Regulation (EU) 2020/741), although to a lesser extent for SolWat in dynamic mode, which treated twice the volume of water and reached cooler temperatures. C. perfringens proved to be the most resistant bacterium tested. The total photovoltaic energy production in the dynamic mode system was more energy efficient than the static mode, being even more efficient than the single PV reference system during the spring (3.5%) and summer (2.7%) test, due to the compensating effect by the cooling of the water on the photovoltaic module against the losses caused by radiation. • Comparison of SolWat systems for implementation as tertiary treatment in a WWTP. • SolWat used: static (without water circulation) and dynamic (with water circulation). • Solar disinfection of secondary effluent of wastewater from a WWTP was evaluated. • Possible reuse of water for various uses (RD 1620/2007 and Regulation (EU) 2020/741). • Favourable PV power generation in dynamic SolWat vs. static mode and single PV module. [ABSTRACT FROM AUTHOR]

Sustainable production of potable water is one of the United Nations sustainable development goals set for 2030. Among available renewable energy resources, solar energy is abundantly available in most of the fresh water scarce rural and remote locations. Moreover, solar distillation units and solar photovoltaic (PV) modules have been acknowledged as suitable candidates for addressing rising fresh water and electricity demands in these regions. In recent years, researchers have proposed a number of novel hybrid solar distillation units where the solar PV modules are integrated with solar thermal distillation units in different ways to harvest both electric power and potable water. In this work, a detailed review highlighting the classification, working principle, performance and features of these novel hybrid units have been carried out. In most of these hybrid units, integration is highly beneficial for solar thermal distillation units rather than for PV modules. Direct utilization of PV module as absorber, condenser and reflector in solar stills has few drawbacks. However, indirect utilization like utilizing electric power and waste heat energy recovered from PV module in distillation units has posed significant distillate yield enhancement up to 300.0%. In some cases, the integrated PV module has even generated sufficient power for carrying out essential domestic activities. Integrated PV module's performance has also improved significantly in few studies but the magnitude of improvement has not been disclosed clearly in most of the studies as more focus has been given to distillation units rather than PV modules. However, these novel hybrid configurations have not been fully explored & optimized and their techno-enviro-economic aspects have not yet been disclosed in these available precious literatures and they are still available as a potential research gap. • Classification of different ways to utilize solar PV modules in water distillation units. • Indirect utilization is more beneficial than direct utilization. • Maximum 25% of PV power is consumed by distillation units. • PV performance and distillate yield enhancement by 10.0% and 300.0%. • Features and research gaps in each configurations has been highlighted. [ABSTRACT FROM AUTHOR]

A hybrid solar water disinfection and energy generation system for meeting the needs of safe drinking water and electricity was designed and tested in Alcalá de Henares (Spain) under summer climatic conditions to demonstrate the feasibility of the concept. Natural water sources with wild strains of Escherichia coli , total coliforms, Enterococcus spp. and Clostridium perfringens (including spores) were studied. Results showed that SOLWAT disinfection efficiency was higher than conventional PET bottles and that the water disinfection reactor located above the PV module did not affect the total energy output produced by the hybrid system in comparison to the single PV module, achieving the same power losses over the 6 h of sun exposure in relation to their power at standard test conditions (STC). [ABSTRACT FROM AUTHOR]

Highlights: [•] Optical transmittance of 18 different commercial heat transfer fluids has been measured. [•] Suitable liquids serving as Absorption Filters are Duratherm 600 and G, Propylene Glycol (PG), pink-dyed PG and Royco782. [•] Long-term degradation tests include low temperature test at 75°C, high temperature test at 150°C, and UV light exposure. [•] Optimum fluid is the industrial Propylene Glycol adapted with a chemically-inert red dye such as Oil Red 235 inorganic dye. [ABSTRACT FROM AUTHOR]

ABSTRACT The first prototype of the hybrid CPV-T ANU-Chromasun micro-concentrator has been installed at The Australian National University, Canberra, Australia. The results of electrical and thermal performance of the micro-concentrator system, including instantaneous and full-day monitoring, show that the combined efficiency of the system can exceed 70%. Over the span of a day, the average electrical efficiency was 8% and the average thermal efficiency was 50%. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: One of the limitations for the widespread use of solar water disinfection technologies in developing regions is the lack of low-cost clean water sensors. A new type of low-cost sensors using photovoltaic solar cells that provide information about received irradiance, temperature, UV irradiance and sunshine duration is presented. A key aspect of the design is the UV irradiance measurement. Two identical cells are used, one of them with a low-cost UV-blocking filter on top, so the total UV irradiance can be calculated as the difference between the two solar cells outputs. The first cell would be measuring UV–vis–NIR and the second only vis–NIR. The UV filter material was explored and a low-cost architectural film was selected. Materials costs for the first prototype were of approximately 4€ excluding labour. Initial testing also included experiments with real polluted water and Escherichia coli, showing the feasibility of the new design. [Copyright &y& Elsevier]

Abstract: First results from a first autonomous optically adapted photocatalytic–photovoltaic system for water purification demonstrate the feasibility of the concept. Complete photodegradation of an organic dye (Methylene Blue) has been achieved when using the system autonomously. For an initial concentration of 0.01g/L of MB dye and an average UV of 4.6W/m2, the total photodecolourisation of the dye after 80min was 95.1% and the increase in the total photovoltaic output power was of 19%. 5L of polluted water was purified. [Copyright &y& Elsevier]

Abstract: A series of initial experiments to demonstrate the feasibility of hybrid photocatalytic–photovoltaic systems for simultaneous water purification and electricity generation have been conducted. Commercial TiO2 (Aeroxide P25) suspended nanoparticles have been used as a photocatalyst and an organic dye (Methylene Blue) as a pollutant. The photovoltaic output of the hybrid system was observed to be related to MB dye photodegradation, whereby as the pollutant degraded the optical transmission to the cell improved. When the dye decolourisation was complete, the increase in photovoltaic output was between 32 and 37% depending on the initial dye concentration. The findings indicate both technologies can work simultaneously, producing drinking water and generating electricity to feed a pump, which establishes the path for a complete autonomous system. [Copyright &y& Elsevier]

Abstract: A comprehensive review on standards for actively-cooled CPV and CPV-T systems is presented. Since these systems lack specific standardisation, this review concludes that the current standards, including the photovoltaic IEEE 1513 and IEC 62108, and the solar thermal EN-12975-2:2006 and ISO 9806-2:1995, are insufficient for qualifying these types of actively-cooled concentrator systems. Additional test specifications for adapting the IEC 62108 and EN-12975-2:2006 standards for actively-cooled CPV and CPV-T systems have been proposed. [Copyright &y& Elsevier]

Abstract: A new concept for a hybrid solar water purification and photovoltaic system for meeting the needs for clean water and electricity in one integrated, autonomous, and cost-effective system is presented in this article. The purified water and power (PWAP) receiver comprises two devices fully integrated into a single unit, using two functionally discrete sub-modules. These two sub-modules can be assembled in two different physical arrangements: (a) one inside the other, whereby the encapsulated photovoltaic cells are embedded into the photo-catalytic reactor; or (b) one above the other, whereby the photovoltaic cells are attached to the photo-catalytic reactor by means of a common encapsulation. Spectral division of a simple PWAP structure, photovoltaic and photo-catalytic output, and associated losses are analysed. In this hybrid system, it has to be remarked that the photovoltaic power output is reduced to the benefit of the water purification process, as only part of the spectrum is used for photovoltaic conversion due to the selective absorption in the different materials. Potential sites for hybrid electricity and water purification systems include both rural and urban areas. Of particular interest are the urban regions of the developing world, which may represent a larger addressable market due to their specific needs. An initial analysis of this potential has been conducted for the case of India. [Copyright &y& Elsevier]

• SolWat (PV + SODIS) electrical performance was evaluated regarding different HRT and PV technologies. • SolWat thin film panels produced more energy than a single module at shorter HRT. • Thin film black surface enhanced far infrared light absorption and heat favouring SODIS. • No clear benefits were observed from shorter HRT in mono and multicrystalline panels. • Thin film technology was found to be the most suitable technology for its integration into SolWat. SolWat is a hybrid photovoltaic (PV) and photochemical technology, which integrating a PV module and a water disinfection reactor on top of it, was developed to meet the needs of safe drinking-water and electricity in developing countries. This paper assessed the effects of the water disinfection reactor on the electrical performance of the PV module integrated into the SolWat system regarding different hydraulic retention times (HRT) and PV technologies. With this aim, several tests were conducted outdoors under natural climatic conditions. Results showed that while no clear benefits were observed from the water disinfection reactor and reduced HRT on the electrical performance of both monocrystalline and multicrystalline technologies, the final energy output of a-Si thin film PV panels benefited from the cooling effect of water on its front surface being able to produce even more energy than a single PV panel when working at shorter HRT. In addition, the working module temperature was always lower when HRT was shorter; its efficiency under the diffuse light conditions created by the water disinfection reactor was better than monocrystalline and multicrystalline technologies; and its black surface enhanced the absorption of far infrared light and heat by the water disinfection reactor favouring higher water temperatures and thus higher disinfection rates. In conclusion, thin film PV technology is the most suitable to be integrated into the hybrid SolWat systems when comparing with monocrystalline and multicrystalline technologies. [ABSTRACT FROM AUTHOR]

A novel SolWat system designed exclusively as a Solar Home System that also meets the drinking water access in a family of a rural community in a developing country has been designed, manufactured and tested outdoors. The system is composed of 5 photovoltaic modules of monocrystalline silicon solar cells technology, each 20 Wp, parallel-interconnected, adding up to a 100 Wp system. The modules have a water reactor on top with the capacity of providing a minimum of 37.5 L per day for a family of 5 members, guaranteeing the minimum daily needs. Experimental campaign run tests of SODIS of 3 h each, running the system 3 times per day (with a total of 9 h of experimentation per day). Results show that the water treatment of 3 h should be increased at certain periods of the day when the UV dose is not sufficient (late in the afternoon). E. coli and Enterococcus spp achieved total inactivation or almost total disinfection. Regarding electrical production, although energy losses of 5.6–10% were observed in comparison with a single PV module, it was sufficient to fully meet the load demand of the solar home system. The system could be used in a household of a developing country, using only solar energy to meet the electricity and drinking water demand. Unlabelled Image • A SODIS + PV system has been designed for providing clean water and electricity. • It treats 37.5 L of water/day for a 5-member family and has a SHS size of 100 Wp. • System disinfects water each 3 h (SODIS batch of 3 h), running 3 times per day. • The 3 h-water treatment period should be adjusted to achieve the required UV dose. • Despite the water on top, PV energy losses are only 5–10% vs. a single PV. [ABSTRACT FROM AUTHOR]

• In the past, PV panels have been cooled with evaporative cooling. • By integrating a solar still below the PV panel, in this work water vapour is converted to desalinated water. • A 5.6% increase in output power and a 14.51 % increase in electrical efficiency were achieved. • It is possible to obtain 0.55 L of desalinated water. The efficiency of photovoltaic panels decreases with the increase in panel temperature while converting light into electricity. The issue of temperature rise and the associated decrease in efficiency has been widely analysed by active and passive cooling methods. In those processes, normally water is used as a cooling medium, and it results in water loss along with power loss due to circulating or compensating for the lost water. The current study aims to address both efficiency as well as water loss by combining an evaporative cooling technique with a solar still. A Photovoltaic panel with rear-side evaporative cooling is attempted by using a jute sack dipped in water at both ends. As a result of capillary action, the water from a solar still rises through the sack and cools the panel's rear side. Solar still operation is ensured by an extended portion of glass. During desalination, the evaporated vapour from the solar still condenses on the back cover of the glass surface and is collected in a collection trough. As a result, the output power increased by 5.6 % and the electrical efficiency increased by 14.51 % and the surface temperature are reduced by 8°C. After seven hours of sunshine, the proposed PV panels and solar still system produced approximately 550 ml of water. [ABSTRACT FROM AUTHOR]