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Abstract Recent trends in residential solar water heating and its efficient usage in Turkey were presented in this study. A novel methodology for determining the optimum orientation and sizing of water-in-glass evacuated tube solar water heating systems has been outlined. Transient modeling was conducted for the prediction of a full year's system performance via the System Advisor Model. In this model, the typical meteorological year data of certain climate zones in Turkey were considered, daily hot water consumption was estimated using the Rand hot water profile, and the monthly averaged mains water temperatures measured by the municipalities were analyzed. In addition, a typical performance rating of a water-in-glass evacuated tube collector produced by the collector manufacturer in Turkey was taken into consideration, and the effects of collector area, storage tank volume, daily average delivery temperature and daily hot water consumption data on the annual solar fraction were analyzed. The verification of the simulation results were compared with the literature and good agreement was obtained. Subsequently, a thermo-economic optimization was employed by using P 1 ‒ P 2 methodology. The methodology presented guarantees to obtain reliable results with a minimal run-time. The diminution in the initial system cost and payback period are shown to be possibly achieved at the level of 7.5% in a 1.5 year period, respectively, while the energy savings are approximately 12% higher annually when implementing optimum results. The results indicate that Turkey would save 300 MW th annually if evacuated tube solar water heaters in Turkey's cities are configured based on optimal sizing. An evacuated solar water heater in a typical residential building in Turkey has the potential to mitigate 5–22 g CO 2 -equivalent/kWh of greenhouse gas emissions per annum if properly installed. Graphical abstract Image Highlights • A methodology for optimizing of water-in-glass collector systems was presented. • A transient modeling was conducted using the System Advisor Model simulation tool. • Verification of the simulation was compared with the literature in good agreement. • A thermo-economic optimization was employed with a minimal run-time. • Optimum collector design was proposed for promoting energy, economy and ecology. [ABSTRACT FROM AUTHOR]

In our search for a better socioeconomic path for water heater usage in China, we studied and compared the annual dynamic thermal performance of solar water heaters (SWHs) in the Jiangsu province. Experiments are conducted in two cities within Jiangsu—Nanjing and Lianyungang—spanning two climate zones. The results show that SWHs have good thermal performance in Jiangsu. The SWHs in Lianyungang show better thermal performance than that in Nanjing, because they receive greater solar radiant energy. Also, from a thermal perspective, vacuum tube solar water heaters (VTSWHs) perform better throughout the year than flat-plate solar water heaters (FPSWHs). Meanwhile, taking socioeconomics into account, gas-assisted flat-plate solar water heaters (GA-VTSWHs) have better performance compared to other types of water heaters. Based on these results, the implications for developing and applying SWHs are derived. This study can be used to optimize operation of the household hot water supply system and use it more efficiently. [ABSTRACT FROM AUTHOR]

A multi-parametric sensitivity analysis of Solar Water Heater (SWH) systems was undertaken for the city of Brisbane in Australia using computational models calibrated by experimental data. The models were calculated using EnergyPlus 8.6. The following technical specification parameters were assessed in the modelling: (i) solar collector efficiency; (ii) solar collector area; (iii) tank volume; (iv) tank heat loss; (v) electric back-up heating power rate; (vi) electric back-up heating position (height) for vertical tanks; and (vii) electric back-up heating temperature range. The site-specific parameters included: (i) solar collector direction; (ii) solar collector tilt angle; (iii) solar collector shadowing; (iv) solar collector dust accumulation; (v) hot water pipe insulation; (vi) hot water pipe length; (vii) electricity tariff time-of-use; and (viii) cold water temperature. User behaviour patterns were comprised of the following parameters: (i) end-use water temperature; (ii) end-use water demand; and (iii) end-use time-of-use. For all parameters, two system types were assessed, namely: (i) thermosiphon systems with natural (passive) circulation in collectors and unstratified horizontal hot water storage tanks; and (ii) split systems with forced (pumped) circulation in collectors and stratified vertical hot water storage tanks. The performance of SWHs was analysed considering both energy performance indicators (i.e. total and peak-hour energy consumption, solar fraction and energy intensity) and level of service indicators (i.e. compliance with recommended hot water temperatures for Legionella spp. control and comfort levels). Notwithstanding the prevalence of thermosiphon systems among SWH technologies, results indicate that split systems usually outperformed thermosiphon systems both in terms of energy efficiency and level of service, and hence should be a preferred option for energy efficiency initiatives and policies. [ABSTRACT FROM AUTHOR]

The present work investigates the suitability of a new method for the calculation of the performance indicators of domestic solar water heating systems, within the framework of the European Directive implementation for energy labeling of water heating devices. The various methodology approaches suggested by the directives for the calculation of the expected energy yield from the solar thermal products are being analyzed. The presence of significant issues of reliability and objectivity is being brought out, particularly with regard to the SOLCAL method, which is used for the estimation of the expected energy yield of a thermal energy system, by means of the characteristics of each individual component which the system consists of. A detailed documentation and experimental validation of a new method for the estimation of the expected energy yield of a solar only water heater is outlined. The performance of the proposed method is assessed based on an extensive experimental investigation, whereby discrepancies of the order of 7% or less were obtained for the daily energy yield. From the comparison of performance of the new method against that of the SOLCAL method it is inferred that the former constitutes a reliable alternative choice in the context of energy labeling. [ABSTRACT FROM AUTHOR]

This paper presents the development through experimental performance characterisation of a pre-heat ICSSWH that utilises a novel thermal diode operation to reduce ambient heat loss during non-collection periods. Using a bespoke thermal flux simulation test facility, 4 prototype versions of the pre-heat thermal diode ICSSWH were produced and evaluated (Mark I to IV) at Ulster University. Each prototype was developed and evolved on the previous design, encompassing performance improvements and fabrication enhancements. The concept has been designed and developed to be a sustainable, pre-heat alternative to other solar water heating systems traditionally used in DHW installations in retro-fit and social housing applications. The highest 6 h and 3 h collection efficiency was 33.2% and 41.97%, respectively under thermally simulated conditions for a unit with capillary matting and 150 mbar internal pressure (MIIIb 17). The lowest system ‘U’ value was 0.98 W m −2 K −1 (long and thin raised pockets, MIV 12) under thermal (solar) flux simulation testing and no draw-off conditions. When the current prototype ICS units are compared with other conventional ICS systems, particularly in terms of thermal retention during non-collection periods, an improved performance is clearly demonstrated. The measured thermal losses were approximately 50% less than other similarly measured systems. [ABSTRACT FROM AUTHOR]

In this study, a MATLAB/SIMULINK model of a solar water heater has been developed and simulated for an aviculture building in Tehran, Iran. The thermal behavior of the subsystems, such as temperature changes of the collector, heat exchanger, and storage tank, etc., has been determined. Three different simulation approaches have been considered. The thermal performance of the system was evaluated by proposing two auxiliary heaters within the storage tank and using them in three different cases. The results showed that the collector surface area has a great impact on the absorber plate average temperature. Also, a greater amount of auxiliary heating would cause the inlet and outlet of the heat exchanger to be equal for a much longer time and thus reduce the heat exchanger efficiency. [ABSTRACT FROM AUTHOR]

In this study, the effect of graphene nanoplatelets (GNP)/distilled water nanofluid on the thermal performance of evacuated tube solar collector (ETSC) water heater was experimentally investigated. The mass percentage of GNP was considered at 0.025, 0.5, 0.075 and 0.1 wt%. The physical and thermal properties of the GNP nanofluids including stability, specific heat capacity, viscosity and thermal conductivity were investigated. The thermal efficiency tests on the solar collector were carried out for varying volumetric flow rate of 0.5, 0.1, and 1.5 L/min while the ASHRAE standard 93–2003 was considered to calculate the efficiency of the collector. The results indicated that the solar collector thermal efficiency gave enhancement up to 90.7% at a flow rate of 1.5 L/min when the GNP nanofluid was used as an absorption medium. The results indicated that by increasing the mass percentage of nanoparticles, thermal energy gain also increases, reaching a higher outlet temperature of the fluid when graphene nanosheets are used. [ABSTRACT FROM AUTHOR]

The optimization of a solar domestic hot water system (SDHWS) for the provinces in certain climate zones of Turkey was investigated in the present study. The optimum design of the system was divided to a three level structure. The simulation level (TRNSYS), the Generalized Pattern Search (GPS) optimization method Hooke-Jeeves Algorithm level (GenOpt) and the interface for the communication between those two levels (TrnOPT). Taking into account the financial (life cycle cost) analysis, the optimum collector area, the optimum collector slope and optimum hot water storage tank volume were determined for each province. The annual simulation of the SDHWS was accomplished with the determined optimum size and the monthly auxiliary heating rate, the monthly solar fraction and the monthly collector efficiency were calculated for each province. In the designed system, the highest auxiliary heating rate was determined 379.63 kWh/month in Hakkari on October and the lowest auxiliary heating rate was determined 177.48 kWh/month in Izmir on October. The lowest monthly solar fractions from the solar water heating system were calculated for Edirne as 8% in December and as 17% in January. The costs of meeting the annual auxiliary heating rate and the annual energy rate to load with electricity and natural gas were compared. The effects of increased utilization of the SDHWS in buildings on the energy supply of Turkey were addressed. [ABSTRACT FROM AUTHOR]

The heating demands are currently fulfilled through conventional technologies based on fossil fuels. However, due to rapid depletion and environmental hazards of fossil fuels, the focus has shifted to harness the heat energy from renewable energy resources such as solar energy. In general, flat plate and evacuated tubes collectors are used for water heating yet there is another technology known as solar thermal tower (STT) which can be used for heating applications. The current study is focussed on real time performance analysis of solar thermal tower water heating system under climate conditions of Taxila, Pakistan. Initially, a mathematical model is developed to design a small capacity solar thermal tower system. The system is simulated using MATLAB for five different climate conditions of Pakistan i.e. Peshawar, Taxila, Multan, Karachi, and Lahore for potential assessment. Afterwards, an experimental setup is developed at Taxila consisting of a cavity type receiver made of stainless tubes, heliostats made of mirror and complete instrumentation for data measurements. The performance analysis is presented in terms of temperature difference (Δ T ), absorbed heat ( Q abs ), and efficiency ( η ) with fixed and variable positions of heliostats for 12 selected days between September and February. The results showed that the maximum temperature difference with fixed heliostats position was 3 °C, Q abs was 27 W and the maximum efficiency was 30%. However, with variable heliostats positions, the maximum value of temperature difference achieved was 16 °C that resulted Q abs 170 W and efficiency 34%. Finally, a reasonable agreement between simulated and experimental results was obtained for climate conditions of Taxila. [ABSTRACT FROM AUTHOR]

How to design water-in-glass evacuated tube solar water heater (WGET-SWH) with high heat collection rates has long been a question. Here, we propose a high-throughput screening (HTS) method based on machine learning to design and screen 3.538125 × 10 8 possible combinations of extrinsic properties of WGET-SWH, to discover promising WGET-SWHs by comparing their predicted heat collection rates. Two new-designed WGET-SWHs were installed experimentally and showed higher heat collection rates (11.32 and 11.44 MJ/m 2 , respectively) than all the 915 measured samples in our previous database. This study shows that we can use the HTS method to modify the design of WGET-SWH with just few knowledge about the highly complicated correlations between the extrinsic properties and heat collection rates of solar water heaters. [ABSTRACT FROM AUTHOR]

The aim of this work is to study the effect of truncation of an integrated solar collector with full CPC reflectors on the optical and thermal performances. The design with untruncated concentrator has a strong connection with a previous study where an old ICS system was designed and experimentally tested and it was already studied in a previous work. The upper part contained two symmetrical parabolic sections with focal axes tilted by θ = 48 ° from the vertical plane. The lower part was constituted by three involute reflectors. Its cylindrical storage tank covered the triangle formed by the three involute parts centers. In order to reduce its size while keeping an acceptable level of the average temperature, minimize its manufacturing cost and facilitate its installation, truncation is suggested. A numerical model based on the detailed geometric characteristics of the full CPC was developed to plot the corresponding profile that was took as reference to switch to a truncated CPC deduced from the latter mathematical equations. A theoretical study was then carried out to predict the optical and thermal behavior of the system and simulate several parameters such as the concentration ratio and the height of the upper concentrating stage. The results are presented and discussed. The developed numerical tool within this work can be considered as important for a future study of the optical performances regarding the angle of acceptance for optimization. [ABSTRACT FROM AUTHOR]

Making a choice between a collective solar domestic water-heating system (CSDWHS) with a single water tank and one with double water tanks is a complicated problem for designers to solve, since it involves many influencing factors, such as cost, function, maintenance, etc. In this paper, a comparison of thermal performance of these two systems based on testing data was made in order to give some guidance to designers. Firstly, a CSDWHS with double water tanks installed in Yuxi, Yunnan Province was tested from 0:00 on 31 October 2015 to 8:00 on 1 November 2015 and from 0:00 on 3 November 2015 to 8:00 on 4 November 2015. Then, thermal performance indices (i.e., energy collected, daily useful energy gain, solar fraction, collector efficiency, system efficiency, system heat-loss factor, and average heat-loss factor) were analyzed to compare the thermal performance according to field-testing data. The results show that the system heatloss factor of the CSDWHS with a single water tank is lower than that with double water tanks, but the average heat-loss factor is higher, so it is difficult to conclude which system exhibits better thermal performance. Still, if real-estate developers do not emphasize cost and if there is enough roof space to place two water tanks, a CSDWHS with double water tanks is a feasible choice because it can store more heat to supply hot water for rainy or cloudy days. The results obtained in this study are useful for designers to optimize the design of a CSDWHS. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) have good properties such as high thermal capacity and constant phase change temperature. Their potential use in solar energy storage is promising. Tests of exposure and constant flow rate are performed to investigate the thermal performance of a domestic solar water heater with solar collector coupled phase-change energy storage (DSWHSCPHES). Due to the low thermal conductivity and high viscosity of PCM, heat transfer in the PCM module is repressed. The thermal performance of the DSWHSCPHES under exposure is inferior to that of traditional water-in-glass evacuated tube solar water heaters (TWGETSWH) with an identical collector area. DSWHSCPHES also performs more efficiently with a constant flow rate than under the condition of exposure. Radiation and initial water temperature have impacts on system performance; with the increase of proportion of diffuse to global radiation and/or initial water temperature, system performance deteriorates and vice versa. [ABSTRACT FROM AUTHOR]

As homes move toward zero energy performance, some designers are drawn toward the solar combisystem due to its ability to increase the energy savings as compared to solar water heater (SWH) systems. However, it is not trivial as to the extent of incremental savings these systems will yield as compared to SWH systems, since the savings are highly dependent on system size and the domestic hot water (DHW) and space heating loads of the residential building. In this paper, the performance of a small combisystem and SWH, as a function of location, size, and load, is investigated using annual simulations. For benchmark thermal loads, the percent increased savings from a combisystem relative to a SWH can be as high as 8% for a 6 m² system and 27% for a 9 m² system in locations with a relatively high solar availability during the heating load season. These incremental savings increase significantly in scenarios with higher space heating loads and low DHW loads. [ABSTRACT FROM AUTHOR]

Solar passive water heaters are potential candidates for enhanced heat transfer. Solar water heaters with an integrated water tank and with the low temperature energy resource are used as the simplest and cheapest recipient devices of the solar energy for heating and supplying hot water in the buildings. The solar thermal performances of one primitive absorber were determined by using both the experimental and the simulation model of it. All materials applied for absorber such as the cover glass, the black colored sands and the V shaped galvanized plate were submerged into the water. The water storage tank was manufactured from galvanized sheet of 0.0015 m in thickness and the effective area of the collector was 0.67 m. The absorber was installed on a compact solar water heater. The constructed flat-plate collectors were tested outdoors. However the simulation results showed that the absorbers operated near to the gray materials and all experimental results showed that the thermal efficiencies of the collector are over than 70 %. [ABSTRACT FROM AUTHOR]

The thermal performance of an integrated collector storage solar water heater (ICSSWH) is numerically examined using the numerical software FLUENT 6.3. As this solar system presents the disadvantage of its high night thermal losses, a new strategy helping to reduce these losses is proposed. A particular system in which the storage tank is covered with an outer glass tube is studied and a parametric study is conducted in order to evaluate the optimal air spacing gap between the water tank and the covering glass tube which minimizes this system's heat losses. A 3D computational fluid dynamics (CFD) model interpreting this modified system is so developed and its thermal performance is compared to that of the noncovered tank based ICSSWH. The analysis of these solar systems daily performance shows that the modified ICSSWH is able to generate more thermal output and presents the advantage of its lower thermal losses. Regarding the night operating, this covered tank based ICSSWH is shown more effective in retaining higher temperatures for longer period, resulting so in lower night thermal losses. Results also suggest that the best performance corresponds to the lowest air gap spacing (L = 0.005 m). [ABSTRACT FROM AUTHOR]

The present work presents and analyzes the results acquired from outdoor experimental measurements of a flat plate solar collector integrated with built-in thermal energy storage. Paraffin wax as a PCM and a nanocomposite of paraffin wax with 1.0 wt% of 20-nm nano-Cu particles were tested as the energy storage medium for TES. Three cases have been investigated, namely without PCM, with PCM, and with the Cu-PCM nanocomposite, at 10°, 20°, and 30° inclination angles of each case. The system performance was evaluated for water heating. The process involved a total change of the 60-l water tank at 7:00 PM and 7:00 AM. The use of water circulation of 0.5 kg/min and setting the collector at a 10° inclination angle was found to be the best operational condition. The measurement result of the tank water temperature at 7:00 AM, after 24 h of operation, was 35.1 °C when the system operated without TES, while the operation with the PCM and with the Cu-PCM nanocomposite resulted in 40.1 °C and 40.7 °C tank water temperatures, respectively. The best performances analyzed were at 10°, with efficiencies of 47.6%, 51.1% and 52.0% for the cases without PCM, with PCM and with Cu-PCM nanocomposite, respectively. This indicates that the enhancement of the system using TES with paraffin wax is considerable, while further enhancement is not significant in the case of nanocomposite. Further measurements with various flow rates are recommended to investigate the performance of the developed solar-TES integrated system. [ABSTRACT FROM AUTHOR]

In order to harvest solar energy, thermal energy storage (TES) system with Phase Change Material (PCM) has been receiving greater attention because of its large energy storage capacity and isothermal behavior during charging and discharging processes. In the present experimental study, shell and tube TES system using paraffin wax was used in a water heating system to analyze its performance for solar water heating application. Energy and exergy including their cost analyses for the TES system were performed. Accordingly, total life cycle cost was calculated for different flow rates of the Heat Transfer Fluid (HTF). With 0.033 kg/min and 0.167 kg/min flow rates of water as HTF, energy efficiencies experienced were 63.88% and 77.41%, respectively, but in exergy analysis, efficiencies were observed to be about 9.58% and 6.02%, respectively. Besides, the total life cycle cost was predicted to be $ 654.61 for 0.033 kg/min flow rate, which could be reduced to $ 609.22 by increasing the flow rate to 0.167 kg/min. Therefore it can be summarized that total life cycle cost decreases with the increase of flow rate. [ABSTRACT FROM AUTHOR]

Numerical study of nonstationary three-dimensional laminar convection is performed in the model of the main element of a solar water-heating installation of the accumulation type in the process of a daily cycle of heat supply. Three-dimensional velocity fields and peculiarities of temperature distributions in the tubular element of installation that are connected with formation of temperature stratification are analyzed at different angles of the element inclination to the horizon. [ABSTRACT FROM AUTHOR]

Highlights: [•] Performance of water-in-glass evacuated tube solar water heaters (SWH) at night was studied. [•] Experimental measurements showed that reverse flow occurred in SWHs at night. [•] Reverse flow in SWHs was very high but the heat loss due to reverse flow was very low. [•] Reverse flow seemed not sensitive to atmospheric clearness but sensitive to collector tilt-angle. [ABSTRACT FROM AUTHOR]

Highlights: [•] We studied a thermosyphon solar water heater composed of high-performance components. [•] A differential equations solution technique is investigated. [•] The influences of the collector and storage losses on the system performance were examined. [•] The storage losses have more influence on the long-term performance. [Copyright &y& Elsevier]

Highlights: [•] A method coupled CitySim with TRNSYS is proposed to evaluate the performance of SWH in urban context. [•] The effect of arbitrary obstructions on SWH can be considered quantitatively. [•] SWH in urban context may consume more primary energy than conventional water heater. [•] The method is helpful to maximize energy saving using SWH in urban context. [ABSTRACT FROM AUTHOR]

The maximum electricity conversion efficiency of the Solar Photovoltaic panel is 8-18% under the Standard Test Condition (STC) temperature of 25 °C. The atmospheric temperature of lndian climatic condition is mostly above 30 °C - 45 °C, it incites 30 °C-80 °C heat over the panel since black body of the PV panel observe more heat, and this temperature majority affect the electrical efficiency of the panel. The newly designed Glass to Glass Photovoltaic Thermal System (G2G-PVTS) is a combined Photovoltaic (PV) and Flat Plate Solar Water Heating System (FPSWHS). In this technology, the water act as a coolant inside the Copper fins and it absorb the heat of the PV panel and stored in the insulated storage tank by way of natural flow of water. The test result shows that the G2G-PVTS electrical efficiency was 0.7% higher than conventional G2T-PV panel, and in addition that 44.37% of thermal efficiency was also stored The simultaneous conversion of electrical and thermal energy was obtained by this system with effective space utilization. The overall efficiency of the G2G-PVTS panel was improved. [ABSTRACT FROM AUTHOR]

The thermal behavior of an integrated collector storage solar water heater (ICSSWH) is numerically studied using the package Fluent 6.3. Based on the good agreement between the numerical results and the experimental data of Chaouachi and Gabsi (Renew Energy Revue 9(2):75-82, ), an attempt to improve this solar system operating was made by equipping the storage tank with radial fins of rectangular profile. A second 3D CFD model was developed and a series of numerical simulations were conducted for various SWH designs which differ in the depth of this extended surface for heat exchange. As the modified surface presents a higher characteristic length for convective heat transfer from the storage tank to the water, the fins equipped storage tank based SWH is determined to have a higher water temperature and a reduced thermal losses coefficient during the day-time period. Regarding the night operating of this water heater, the results suggest that the modified system presents higher thermal losses. [ABSTRACT FROM AUTHOR]

Abstract: The technical and environmental performance of a solar water heater (SWH) is examined using the method of life cycle assessment (LCA). The present LCA study quantifies the environmental benefits of the installation of a SWH with electricity as auxiliary for domestic use in the city of Thessaloniki. Solar thermal heating produces no emissions during operation but some small levels of emissions are produced during the manufacture and installation of components and systems. This work examines the manufacturing stages of the SWH and records resource consumption and waste streams to the environment. The system boundary includes the production of raw materials such as steel, glass, copper, aluminium, glass fibber and polyurethane insulators, the manufacturing of the various parts of the SWH such as the solar collector and the heat storage tank, and finally the assembly process. The functional unit chosen is 1 MW of produced hot water. The environmental impacts taken into consideration in the study, are the greenhouse effect, ozone depletion, acidification, eutrophication, heavy metals, carcinogens, winter smog and summer smog. The system can provide 1702 kWh year−1 and the solar contribution is 58.5%. The financial characteristics of the system investigated give life cycle savings equal to 4280.0 € and pay-back time equal to 5 years. [Copyright &y& Elsevier]

We are commemorating the Education Decade for Sustainable Development. If we want to create positive towards our environment and its sustainable development we have to begin working at school. It is necessary to show our students what problems of the environment are and which solutions can be adopted. That is the reason we have planned this activity in our secondary school. We do think that by doing daily activities we have a good opportunity to fulfil this goal. An example of such experiences is the fabrication of a solar hot water heater to make them and their families more environment conscience. [ABSTRACT FROM AUTHOR]

Thermal and optical performance of solar water disinfecting systems using parabolic trough collector, PTC, have been investigated experimentally and numerically. Four PTCs systems were designed, manufactured and field tested under the same weather conditions of Cairo 30° N. The four systems were installed to be compared thermally and biologically. Each system consists of a 2-m2 PTC and line-focus pipe to carry the water sample to be disinfected. In the first system (thermal system), a black painted stainless steel pipe covered by Pyrex glass envelope, to minimize the convective and radiative heat loss, is supported through the line-focus of the PTC. While in the second system (optical system) the contaminated water is used as absorber through a Pyrex glass tube, the two above processes are considered respectively in the third system. In the fourth system, a black tube including and surrounded by the contaminated water are considered as the absorber. The contaminated water is passed through the annular space between the Pyrex glass tube and the collector absorber. The experimental results indicate that the third system has better performance than the other studied systems fromthe biological point of view with twice area. It has the minimum biological contamination, Spore-former bacteria count, total bacterial counts and total coliforms. While the thermal system is thermally efficient, the optical system is not recommended to use alone. A numerical modeling of the systems was developed and validated by experimental data. The annual performance of the systems is presented. Under the same environmental and technical conditions the third system can be considered as the most efficient one that can produce about Million liter of clean water a year. [ABSTRACT FROM AUTHOR]

The performances of solar water heating systems have improved steadily over recent years due to improved component quality and design. Solar water heating systems in Northern Maritime climates, however, are still not viable economically. In order to make a significant impact on the domestic hot water heating market, solar water heaters must be innovative, cost-effective, and adaptable for retro-fit installation. This paper investigates experimentally the performance of a novel heat exchanger (the 'Solasyphon') designed and developed for external connection to an existing traditional single-coil hot water cylinder. The connection of the novel heat exchanger to an existing system reduces the cost of installation as it avoids the need to replace the existing single-coil hot water cylinder with a twin-coil system. However, the connection of this Solasyphon to a solar water heating system has negative effects on heat losses especially at higher temperatures based on the size of the solar collector. The experimentation was carried out under outdoor and indoor control operating conditions. This paper presents the monitored performance of the Solasyphon compared with that of a conventional solar water heater with a coiled heat exchanger and the negative effects regarding the heat losses resulting from the small size of the solar collector especially at high inlet temperatures (greater than 70 °C). [ABSTRACT FROM AUTHOR]