With a perspective of climate change universally, numerous technologies are under development in the field of renewable energy resources from last two to three dacades. Amongst them, the more emphasis is given to huge and free source of solar radiation. Number of advanced techniques namely automatic PV tracker, solar thermal hybrid collector, concentrated solar technology (CST), Fresnel lens are in lined in a such renewable energy sources. The main objective of doing this is to improve the performance of PV panel and to generate maximum possible energy. This is due to the reason that, photovoltaic panel exhibits certain limitations under high temperature. Its performance may degrade under such circumstances. Steps are required to be taken to reduce this high temperature of PV panel. This can be full filed by reconstructing the solar photovoltaic panels with thermalcollector system. A sound design of PV/T system can extract as much as possible heat from PV laminate with heating fluid (either water or air) to reduce the operating temperature of PV and keep electrical efficiency at sufficient level. As an effect, solar radiation conversion can be obtained higher than a PV module alone. This paper includes various aspects of hybridize solar PV/T collector system such as constraints of PV module, various possible designs of hybrid systems and its benefits.
A variety of technologies exist to capture solar radiation, but of particular interest of authors is evacuated tube technology. Numerous authors have noted that ETSCs have much greater efficiencies than the common FPC, especially at low temperature and isolation. For instance, Ayompe et al. Conducted a field study to compare the performance of an FPC and a heat pipe ETSC for domestic water heating system. With similar environmental conditions, the collector efficiencies were found to be 46.1% and 60.7% and the system efficiencies were found to be 37.9% and 50.3% for FPC and heat pipe ETSC, respectively. An ETC is made of parallel evacuated glass pipes. Each evacuated pipe consists of two tubes, one is inner and the other is outer tube. The inner tube is coated with selective coating while the outer tube is transparent. Light rays pass through the transparent outer tube and are absorbed by the inner tube. Both the inner and outer tubes have minimal reflection properties. The inner tube gets heated while the sunlight passes through the outer tube and to keep the heat inside the inner tube, a vacuum is created which allows the solar radiation to go through but does not allow the heat to transfer. In order to create the vacuum, the two tubes are fused together on top and the existing air is pumped out. Thus the heat stays inside the inner pipe sand collects solar radiation efficiently. Therefore, an ETSC is the most efficient solar thermalcollector. An ETSC, unlike an FPC, can work under any weather conditions while it provides acceptable heat efficiency.
This work investigates the performance of combined hybrid high concen- trated photovoltaic/thermalcollector (HCPV/T) in Kuwait harsh climate. The proposed system consists of triple junction solar cells (InGaP/InGaAs/Ge) attached to heat source to discharge thermal energy to cooling media. Pub- lished HCPV/T models do not consider the effect of shunt resistance which greatly affects the system performance. So, a single diode model employing five parameters including the effect of shunt resistance is adapted to analyze the proposed system. To analyze the thermal performance of the proposed system, a two-dimensional thermal model based on the technique of finite difference is introduced to determine the efficiency of the hybrid HCPV/T system. The present developed subroutines are integrated with other involved codes in TRNSYS software to calculate HCPV/T system efficiency. Electrical and thermal as well as the whole system efficiency at different weather cir- cumstances are evaluated and assessed. The effect of different weather condi- tions, cell temperature, concentration ratio and the temperatures of the coo- lant fluid on system performance are studied. Current results indicate that the model of single diode is a reliable one rather than using the two-diode com- plex model. Compared to measurements provided by high concentrated PV manufacturer, the current results revealed a total root mean square error of approximately 1.94%. Present predictions show that PV cell temperature has logarithmic increase with the rise in concentration ratio but with low values till concentration ratio of 400 suns after that the rise is faster at higher con- centration values up to 1500 suns. Results also revealed that hybrid HCPV/T system works effectively specially in severe hot climate where thermal effi- ciency increases with high surrounding temperature for higher values of con- centration ratio. In addition, an increase of approximately 15% in thermal ef- How to cite this paper: Kandil, K.M.,
The main objective of this study was to use the augmented intuitive logics theory to cope with the current environmental uncertainty that the solar thermalcollector market in Germany is experiencing. Through this confirmatory-exploratory research it was found, regarding the literature reviewed and data employed, that the two critical forces which slow the adoption of solar thermal collectors in Germany are the awareness/knowledge of the end-consumer towards the technology (consumer interest) and the final price (cost) of the technology. On the other hand, subsidies, as expected, don’t have an influence on the adoption of solar thermal collectors. The reasoning may be because of the findings of Jager (2006) and Huang et al. (2019) that either consumers are not aware of the incentives or that other technologies have better promotion.
A hybrid solar collector was designed to investigate the effects of combining two different solar collector techniques on the overall collector’s effectiveness. While most solar collectors focus only on one solar collection method, the small hybrid system uses a flat plate collector in conjunction with five eva- cuated tubes to absorb the most energy possible from both direct and diffuse solar radiation. Data was collected over four months while the system oper- ated at different flow rates and with various levels of available insolation from the sun to evaluate the performance of the solar collector. To understand the relative contribution of the flat plate collector and the evacuated tubes, tem- perature differences across each part of the system were measured. The re- sults indicate the average first law efficiency of the hybrid system is 43.3%, significantly higher than the performance of the flat plate alone. An exergy analysis was performed for this system to assess the performance of the flat plate system by itself. Results of the second law analysis were comparable to the exergetic efficiencies of other experimental collectors, around 4%. Though the efficiencies were in the expected range, they reveal that further improve- ments to the system are possible.
A theoretical discussion of the concept of ‘energy value’ is presented, with the aim of developing methodologies that could be used in optimisation studies to compare the value of electrical and thermal energy. Three approaches are discussed; thermodynamic methods, using second law concepts of energy usefulness; economic valuation of the hot water and electricity through levelised energy costs; and environmental valuation, based on the greenhouse gas emissions associated with the generation of hot water and electricity. It is proposed that the value of electrical energy and thermal energy is best compared using a simple ratio.
Solar energy is one of the best candidates to produce process heat at mid temperatures to satisfy the industrial demand. The interest in improving solar thermalcollector efficiencies is huge, in order to take full advantage from this source of energy. TVPSolar is a leading company in the field of high-performance solar energy conversion that develops and produces an innovative flat-plate solar thermalcollector under high vacuum. Vacuum technology ensures that both gas convective and conductive losses are reduced to a negligible level, so that these flat-panels are able to reach high working temperatures (up to 200 °C) . Concentrating Solar Power technology (CSP), combined with high vacuum insulation, could be an alternative to reach higher working temperatures. The sunlight concentration technology splits into two different broad categories: imaging and non-imaging concentration. As regarding Solar Thermal (ST) and photovoltaic (PV) applications, non-imaging concentration has been an interesting option, since mid-1960s . CSP usually uses only direct-beam sunlight , so mirrors require high cleaning standards and tracking systems to efficiently harness solar energy in day-light hours, resulting in high maintenance costs and installation issues. Compound Parabolic Concentrator (CPC) is an example of non-imaging concentration of sunlight that could be designed for stationary or passive tracking thus having acceptable concentration ratio. Moreover, it can collect both direct-beam sunlight and part of diffuse light (only rays within the acceptance angle)  and concentrate them on an absorber tube. A new frontier in high efficiency solar collection could be a high vacuum flat solar panel, thick enough to be equipped with CPC. The CPC installed in a high vacuum envelope leads to various advantages: no need for mirror cleaning, no corrosion due to atmospheric agents, better insulation resulting in thermal loss reduction, possibility to deposit a IR reflective coating on the interior side of the glass to benefit from ‘photon recycling’ mechanism . A pioneering work  has experimentally investigated the idea to place a CPC under vacuum to reach the high temperatures needed for methanol reforming but CPC dimensions and performances were limited by the small volume of the cylindrical vacuum chamber. To extend CPC sizes the vacuum chamber must increase too, so the surface under vacuum needs a mechanical support to sustain the glass against the atmospheric pressure and the CPC has to be designed to respect the support mechanical constraint.
(CO) is a solar thermalcollector for heating water which is composed of two parts connected together in series. First part is a flat collector (FP), and second part is an evacuated tube collector (ET) of the type (U-pipe). Water enters the bottom of (FP) and exit the top of (ET). Reference area for the two collectors are equal, which are: Aperture area A a , Absorber surface area exposed to solar radiation A A , and Gross area A G . The Design and the manufacturing are as follows:
The solar collector is considered as the heart of a solar thermal system. The main function of the solar thermalcollector is to absorb solar radiation and convert it into heat to a fluid with the maximum possible efficiency . The main component of the collector is absorber which generates heat by absorption of the solar radiation . Also, the absorber must be designed with low emission capacity in the heat radiation spectrum and high absorption capacity in the solar spectrum . The absorber contains pipes or sheets filled up with a heat transfer medium, and the medium flows to the collector to absorb the heat from solar radiation and return back to the hot water store. The heat exchanger is occasionally used to draw heat from the water-glycol mixture that is circulated in a closed circuit . Moreover, there is limited heat loss to the ambient in the collector by using thermal insulation underneath the absorber and transparent cover in front .
low efficiency and high cost effective ratio, solar thermal collectors possess superior performance over the solar cell (Kalogirou 2004). In solar thermalcollector, where the solar energy is collected directly from the sun and the collector field with the working fluid then that heat is transferred to produce steam for generating power. The main advantage of the solar thermal energy system is that the energy can be stored in other forms and can be used when the sun is not visible. There are different types of solar thermal collectors depending on the design and uses such as: low temperature collector for space heating and cooling, medium temperature collector for cooking, and high temperature collector for power generation. The high temperature solar power is the Concentrated Solar Power (CSP) system where mirrors or lenses are used to concentrate sunlight from a large area and stored in collector filled with heat transfer fluid (HTF). The CSP system has different designs such as parabolic trough, power tower, and dish. CSP system is the growing technology for electricity generation. On commercial level application 14MW Solar Energy Generating System or SEGS plant was built first in California, US in 1980 and now worldwide in 2012 it’s become 2553 MW. Also 2000 MW plants are in under construction all over the world (Coggin 2013).
PV cells will drop with the increase in the operating temperature of PV panels; however, water circulation in PV-T system can help to carry heat away from the PV cells thereby cool down the cells and improve the electrical efficiency. Alobaid et al. (2018) developed a mathematical model of a PV- T system to calculate the system performance. In (Ozgoren et al., 2013), the conversion electrical efficiency of the PV-T system might be improved on average about 10% compared to PV system, and the maximum thermal efficiency of the system was found to be 51%. Although PV-T system is an effective way to utilize the solar energy, the thermal component of this system may become under-performed compared to the solar thermalcollector. In (Agbidi et al., 2016), a 2% increase in electrical efficiency of PV cells and a 5% decrease in thermal component of PV-T system are calculated compared to traditional PV and SWH systems.
Most of the solar thermal collectors used worldwide are evacuated tube collectors, since China has by far the largest solar thermal market and almost all collectors used in China are of the type evacuated tube. In contrast, about 90% of the solar collectors used in Europe are flat plate collectors. Up to now, almost all collectors use a liquid heat transfer medium, but use of air heating collector is increasing which is based on these characteristics. Which type of collector “is best” depends on the intended application, location of use, required performance and operating temperatures, the typical ambient temperature range, the type of heating system in which the collector is to be integrated, as well as on mounting and aesthetic requirements, and of course the available budget. However, the most important factor for choosing a solar collector type is the required operating temperature range. The application areas are performed by their typical temperature ranges and the related collector types with their typical outlet temperatures .
Figures 5 to 8 shows that the thermal efficiency is found to be higher on DGFPSWH than SGFPSWH with the different mass flow rate (0.0041kg/s, 0.0083 and 0.0125kg/s). It is evident from fig 9 to 10 shows that water out let temperature gained by water is more at experimental conditions with DGFPSWH compared to SGFPSWH. As the mass flow rate of water increases the thermal efficiency and heat gained by the water also increases. Hence both are directly proportional to each other. Figure-11 shows that time vs. absorber plate temperature for 0.0041 kg/s. Figure-12 shows that time vs. ambient temperature for three different dates. Figure-13 shows that solar intensity for three different dates.
Lippke  has compared the results of his model with the results of real plant conditions for winter and sum- mer seasons to test the accuracy. It is concluded that the model is inadequate to fully match with actual solar field conditions. Valan and Sornakumar  have used a computer simulation program to model the parabolic trough collector with hot water generation system with a well-mixed type storage tank. From the verification of the model with actual generation 6% deviation is obtained. Yadav et al.  have examined, analysed and tested the parabolic trough collector with different type of reflectors. They identified aluminium sheet as cost effective material to use as reflector. In Spain, there are three power plants namely Andasol 1, Andasol 2 and Andasol 3 that are being operated using parabolic trough collector technology with a capacity of 50 MW each. The annual peak efficiency of each plant is 28% and average efficiency is 15%. The plants are operating with thermal stor- age of 7.5 hours using molten salt . Price et al.  have validated their FLAGSOL model based on Parabolic Trough Collector. The projected performance and actual performance of a 30 MW Solar Energy Generation System (SEGS) plant over a full year of operation is 6%. This is developed by KJC Operating Company at Kramer Junction, California. Purohit  et al. evaluate the CSP potential of 2000 GW in north-western India in the available waste land and solar radiation assessment with viability of different technologies with 50 MW ca- pacity of PTC based plant. Similar to our simulation study, earlier workers have also computed for different plants. However, our study is more general and broad based.
of the adsorber-collector is required to ensure the useful amount of solar energy necessary for system functioning during a very short time. So, it is recommended to use a heat transfer fluid instead of direct heating by solar radi- ation. Thus, we can isolate the upper side of the adsorber- collector that represents the large hole of the heat, and we command the heating time by the temperature and the flow rate of the heat transfer fluid. The fluid will flow in
The use of solar energy is centered at present on photovoltaic and thermal solar energy conversion systems. In the first- named, solar energy is converted into electricity directly by a photoelectric cell. The obtainable outputs are, however still limited. Higher outputs can be achieved by solar thermal conversion. In this process solar energy is received and transferred by a collector system to a working fluid.
an eminent disaster .Meeting this energy demand in a sustainable manner calls for major transformations in the energy sector. A vast transition to renewable energy resources such as solar energy is the best option in this regard and also for alleviating poverty in developing countries where the majority of people do not have access to modern forms of energy. Renewable energy resources, due to their inherent decentralised nature can contribute, to a greater extent, to this goal. Hybrid photovoltaic/thermal (PV/T) system, which converts incident solar energy into both electrical and thermal energy, is one of the best options with regards to this. In a typical PV panel, only 5- 20% of the incident sunlight is converted into electricity, while over 80% is converted into heat and thrown away . In a PV/T module, this heat can be extracted and used effectively by attaching a heat exchanger behind the PV module with either air or water as a heat transport medium. This will allow the PV component to operate at its peak electrical output and mitigates the degradation problem of the PV cells due to overheating. The system therefore, generates thermal energy in addition to electrical energy from one surface area. This is highly desirable in that it solves the growing problem of "competing roof space," which occurs when a roof is covered completely in standard modules leaving no room for other solar technologies. Research in PV/T systems has been ongoing since the mid 1970s and various designs of the system have been developed and studied theoretically, numerically and experimentally [3-9]. The most recent works on these systems focus on finding the system design and operating factors which would result in increased electrical and thermal efficiencies [10-13]. The research work performed to date has revealed the potential of the hybrid technology for a variety of applications . In this study, a steady state thermal model of a PV/T air solar collector under natural flow mode was developed, validated from experimental data and then used to study the effects of various parameters on the performance of the system.
Extensive investigations have been carried out on the optimum design of conventional and modified solar air heaters, in order to search for efficient and inexpensive designs suitable for mass production for different practical applications. The researchers have given their attention to the effects of design and operational parameters, type of flow passes, number of glazing and type of absorber flat, corrugated or finned, on the thermal performance of solar air heaters (Ratna et al., 1991; Ratna et al., 1992; Choudhury et al., 1995; Karim and Hawlader, 2004). Ratna et al. (1991) has presented theoretical parametric analysis of a corrugated solar air heater with and without cover, where they obtained the optimum flow channel depth, for maximum heat at lowest collector cost. Ratna et al. (1992) has found that there exists an optimum mass flow rate corresponding to an optimum flow channel depth. This result has been concluded after conducting a study on 10 different designs of solar air heaters. Choudhury et al. (1995) has calculated the ratio of the annual cost and the annual energy gain for two- pass solar air heaters with single and double covers above the absorber.
A flat plate collector, passive solar dryer with dimension 0.8m x 0.6m x 0.4m has been design and constructed with locally available materials such as plywood, aluminum surfaced roofing sheet lined on the inside, with the floor plate painted black as the black body. The black paint used has an absorbance of 0.96. A comparative test carried out on the drying Okra (Hibisicus esculentus) revealed an extent of 91% moisture removal by the solar cabinet drying and 86% for open air drying as against 89% literature standards. These methods are simple and illustrate the fact that constructions of efficient passive solar dryers are possible and achievable by our local users on a do-it-yourself basis, and this will minimize cost and over dependence on electricity for drying vegetables at home.