Flat-plate Collector Research Articles

Enhanced performance of photovoltaic thermal module and solar thermal flat plate collector connected in series through integration with phase change materials: A comparative study

The decline in photovoltaic cell efficiency due to temperature elevation, coupled with solar energy's inherent intermittency, presents challenges for solar systems, including photovoltaic panels and solar thermal (ST) collectors. The integration of phase change materials (PCMs) emerges as a promising solution to enhance thermal energy storage and regulation, thereby improving system performance and sustainability. This study investigates the performance of series-connected photovoltaic thermal (PVT) and ST systems with integrated PCMs from energy and exergy viewpoints, utilizing a 3D transient numerical simulation. The proposed system's performance is compared with that lacking a PCM across various heat transfer fluid mass flow rates. Suitable PCM selection based on melting temperature is explored, along with PCM layer thickness and nanoparticle augmentation. The research highlights that PCM integration effectively regulates PV cell temperature, enhancing electrical power and exergy rate. While increasing the mass flow rate improves thermal and electrical power, it reduces the thermal exergy rate. Comparing different PCMs (RT28 HC, RT35 HC, and RT44 HC), the RT28 HC PCM provides the lowest temperature of PV cells and the best electrical performance during the day. Moreover, increasing PCM layer thickness results in lowering PV cell and outlet temperatures and storing more heat. Nanoparticles added to PCMs lead to a marginal improvement in energy and exergy, especially for the system with RT28 HC. This analysis emphasizes PCM integration's role in enhancing solar thermal system performance, highlighting the importance of considering the PCM's melting temperature for effective thermal energy management.

Development of crude oil desalination unit by using solar flat plate collectors

To date, two-thirds of the world's crude oil reservoirs need desalination treatment to remove the salt content of crude oil. Ensuring the quality of produced crude oil shows the critical need for desalting units. But, these plants are one of the high-energy consuming processes, especially in the indirect-fired heaters. In this concern, exergy analysis investigated the thermodynamic efficiency of the plant's equipment. Aspen Hysys, and Matlab software are used for simulating and calculating the integrated system based on solar flat plate collectors. Based on exergy analysis, the most inefficient equipment are the skimmer tank, and dual indirect fired heaters by 680, 262 and 216 kW, respectively. Regarding the high rate of exergy destruction in the indirect fired heaters, implementing solar flat plate collectors as alternative equipment that is economically affordable was considered. The desalination unit has significant potential for using solar flat plate collectors, as determined by key solar characteristics such as temperature, clearness index, and daylight length. Mathematical modeling shows that maximum solar irradiation was attained at altitude angle (31°). The economical optimal area was assessed based on the life cycle saving cost parameter. After obtaining the optimal area, it was found that using 52000 m2 of solar flat plate can supply a proper substitute for inefficient heaters. A comprehensive economic analysis of this proposed plan is based on effective indicators, such as purchase side costs, maintenance costs, and fuel inflation rate. The economic results show that the investment cost will be reimbursed 14 years after start-up. This optimum area can reduce CO2 emission of heaters up to 83 %.

Prediction of radiation characteristics of solar collectors with multiple geometrical configurations based on Monte Carlo considering absorption element

This paper presents a study on the optical properties of direct absorption solar collector (DASC) modules with different geometrical configurations considering absorption elements. Three DASC module models, namely flat plates, circular tubes, and tri-prisms, were established and solved using the Monte Carlo method and Mie theory. The accuracy of the results was well verified with the reference data. The results show that the DASC with Si absorption elements exhibited higher absorbance than the DASC with TiO2 absorption elements. It is observed that SiO2@Ni nanofluid exhibited the highest absorbance and lowest reflectance, while TiO2 nanofluid displayed the lowest absorbance and highest reflectance. The absorbance of the nanofluids decreases and the reflectance of systems increases with the increasing particle size of the nanofluid. At incident light angles of 0° and 15°, tri-prism collectors outperform other geometric configurations of collectors. At 30° and 45°, circular tube collectors perform best. At 60° and 75°, flat plate collectors show superior performance. Overall, the tri-prism collector using SiO2@Ni nanofluid coupled with Si absorption elements can improve the efficiency of solar energy utilization compared to the other types of solar collectors.

Performance analysis of V-corrugated flat plate collector containing binary crystal thermal storage materials

Flat plate solar air collectors can further increase their overall thermal conductivity and heat storage capacity by using phase change materials (PCM) and refining their structural design, which will increase their stability and effectiveness of heat collection. Based on sodium sulfate decahydrate (SSD, Na2SO4·10H2O) and sodium acetate trihydrate (SAT, CH3COONa·3H2O), this research proposes a novel manufacturing procedure to manufacture a new binary mixed hydrated salt (SSD/SAT), which addresses phase separation and undercooling difficulties.The latent heat of phase transition hits 229 J/g−1 when the material's phase transition temperature is 61.71 °C. Furthermore, the numerical modeling of the SSD/SAT material's heat collection performance was conducted when it was integrated into a V-corrugated flat plate solar collector (VC-FPSC). The collector has been found to be able to extend the heat and boost the efficiency.

Formulation of an Efficiency Model Valid for High Vacuum Flat Plate Collectors

High Vacuum Flat Plate Collectors (HVFPCs) are the only type of flat plate thermal collectors capable of producing thermal energy for middle-temperature applications (up to 200 °C). As the trend in research plans is to develop new Selective Solar Absorbers to extend the range of HVFPC application up to 250 °C, it is necessary to correctly evaluate the collector efficiency up to such temperatures to predict the energy production accurately. We propose an efficiency model for these collectors based on the selective absorber optical properties. The proposed efficiency model explicitly includes the radiative heat exchange with the ambient, which is the main source of thermal losses for evacuated collectors at high temperatures. It also decouples the radiative losses that depend on the optical properties of the absorber adopted from the other thermal losses due to HVFPC architecture. The model has been validated by applying it to MT-Power HVFPC manufactured by TVP-Solar. The dissipative losses other than thermal radiation were found to be mostly conductive with a linear coefficient k = 0.258 W/m2K. The efficiency model has been also used to predict the energy production of HVFPCs equipped with new, optimized Selective Solar Absorbers developed in recent years. Considering the 2019 meteorological data in Cairo and an operating temperature of 250 °C, the annual energy production of an HVFPC equipped with an optimized absorber is estimated to be 638 kWh/m2.

Performance investigation of solar water heating system using flat-plate absorber integrated with thermal storage

The solar water heating (SWH) technology is a cost-effective method of harnessing solar energy and widely used in various countries worldwide. Adding thermal storage to the flat-plate collector increases the performance of the SWH system. It contributes to reduce energy loss to the top and increases energy transfer to the water. A novel composite material as thermal storage integrated with a flat-plate collector is constructed to make it effective in absorbing and storing heat energy. This work aims to investigate the performance of SWH system by integrating Al + Al2O3 composite to the flat-plate collector at the bottom as thermal storage. The performances of two models of absorber plates including a standard flat-plate collector and with Al + Al2O3 composite as thermal storage are investigated experimentally. The Al + Al2O3 composites were also tested and characterized to obtain their thermal properties. The results show that adding Al + Al2O3 composite as the thermal storage to the absorber plate contributes to increase absorption of solar irradiation, heat storage, and thermal efficiency of the collector. Then, the collector model with Al + Al2O3 composite as the thermal storage provides higher thermal efficiency than that of the standard model. For example, the thermal efficiency of the collector model with composite thermal storage of alumina 35% and aluminum 65% at angle variation increase of 5.1 % (0°), 7.5 % (10°), and 2.5 % (30°). Thermal properties of Al + Al2O3 composites as the thermal storage are also presented. It concludes that the greater percentage of alumina content, the lower value of the thermal properties of the composite obtained.

Performance enhancement of indirect solar dryer with offset strip fins: Experimental investigation and comparative analysis

In the present study, two indirect type solar dryers were designed, fabricated and experimentally investigated, one is equipped with a conventional flat plate collector, and the other is integrated with offset strip fins (OSF). The objective is to study the effect of OSF on the performance of the dryer. A series of experimental tests were conducted at the applied research unit in the semi-arid region of Ghardaia using locally available materials. The first test was starting the solar dryers with an empty chamber and the second with filled product. The peak and average temperature difference at the outlet of the collector were 11.3 and 8 °C respectively, in favor of OSF absorber. The courgette was dried to 0.69 (kg water/kg dry basis) from an initial moisture content of 26.24 (kg water/kg dry basis) in 20 h 18 min and 35 h 45 min in the solar dryer with OSF and without, respectively. The results show a high drying rate using the dryer with OSF compared the dryer with conventional collector. Also, Midilli-Kucuk model provided the best agreements between experimental and predicted moisture ratios. Average effective moisture diffusivity of 1.798x10−09 and 1.179x10−09 m2/s for the dryer with OSF and without, respectively. A 33 % increase in economic efficiency in favor the OSF dryer with 0.95 years payback period. Also, a reduced amount of GHGs makes the dryers environmental friendly.

SunSync Innovation: Empowering Traditional Solar Flat Plate Collectors with Autonomous Sun-Tracking for Tea Leaf Drying

Aim: This research focused on post-harvest technology for preserving tea leaves. The research introduces an innovative approach by incorporating an autonomous solar tracker into a flat plate solar collector, strategically optimizing its orientation towards the sun. The solar tracker, a low-cost and fully automatic prototype, plays a pivotal role in maximizing incident solar rays, thereby enhancing the overall energy absorption efficiency of the system at the same time increasing the quality of dried tea leaves.
 Methodology: The investigation delves into the realm of indirect solar drying methodologies, with a specific focus on the Sun-Tracking Solar Dryer (STSD). This sophisticated apparatus, engineered through the integration of light-dependent resistors, a wiper DC motor with gearbox, and a microcontroller, was developed within the confines of the Agricultural and Food Engineering department at IIT Kharagpur. Subsequent to its development, the study entails a comparative analysis wherein the position of the absorber in the dryer, as ascertained by the developed prototype, is juxtaposed with the ideal position requisite for optimal solar light incidence. Moreover, an examination of the dried tea leaves produced by the prototype is conducted, involving a comprehensive comparison with those dried using the conventional open sun drying method.
 Results: The instantiated prototype demonstrated commendable efficacy in aligning with the ideal position, exhibiting an average deviation of 3.25 degrees. Facilitated by this prototype, the attainment of the targeted moisture content in tea leaves was expedited, culminating 2 hours earlier than the conventional open sun drying method. The resultant dried product manifested a water activity of 0.531 and a DPPH radical scavenging activity of 73.53%, both registering a reduction in comparison to the open sun drying counterpart. Concurrently, the total phenolic content exhibited an increment of 11.48% when contrasted with the open sun drying process.
 Conclusion: The affordably developed prototype demonstrated exceptional capabilities in sun tracking, showcasing the promising potential for augmenting the efficiency of conventional flat plate solar collectors. Additionally, its performance in preserving the quality attributes of dried tea leaves was commendable.

Thermal and Electrical Analysis of N-PVT-FPC Hybrid Active Heating of Biogas Plant

Abstract In order to increase biogas production during winter months/cold climatic conditions, a self-sustained N-photovoltaic thermal and flat plate collector (PVT-FPC) hybrid active heating biogas plant has been analyzed in terms of thermal energy and electrical energy. A general analytical expression for thermal and electrical energy of the biogas plant has been derived as a function of climatic and design parameters from one order coupled differential equations. Various photovoltaic thermal and flat plate collector (N-PVT-FPC) configurations have been considered for optimizing maximum electrical and thermal energy gain for a given total number of N-PVT-FPC collectors. Based on mathematical computation for Indian cold climatic conditions, it has been found that the N-PVT-FPC combination is always better than the flat plate collector-photovoltaic thermal (N-FPC-PVT) collector for maximum electrical and thermal energy. Overall exergy analysis of hybrid active heating of biogas plants has also been carried out.

Thermal analysis on a novel natural convection flat plate collector with perforated tilted transparent insulation material parallel slats (TIM-PS) in Mediterranean climate

The purpose of this research is the evaluation of heat transfer by natural convection in an innovative flat plate solar collector operating in natural convection mode. The design consists of inclined, perforated slats of transparent insulation material installed between the absorber and the glass cover. Hourly climatic data on the four specific days of solstices and equinoxes was used to investigate the behavior of the novel collector design in the city of Monastir; Tunisia. A comprehensive process, ANSYS FLUENT, was implemented to properly evaluate the thermal performance of the collector. In order to obtain accurate thermal properties of the smart collector façade unit containing the TIM-PS to exploit in the simulation, a validated three-dimensional finite volume model developed using the CFD software was used to solve the conductive, convective and radiative heat transfer properties of the system. We have explored in depth the effect of optical characteristics of the TIM-PS on the collector performance. Present research focuses on the analysis of thermal efficiency profile of flat plate collector with innovative façade in comparison with conventional collector for different climatic conditions. The analysis indicated that innovative façade collector’s efficiency is highly influenced by solar intensity. It was found that TIM-PS façade can effectively reduce the convective heat losses through the front of collector. The simulation results show that perforated tilted TIM-PS offer better performance than conventional façade of collector during all the seasons of the year. Simulations performed for one year predict that with careful selection of the parallel slats properties, the new façade system can generate an efficiency up to 83% in June, 76% in September, 53% in March and 42% in December. The results of the thermal evaluation of this research will help guide the future development of this system, as we have demonstrated that the innovative façade collector can be used all year round. In conclusion, the TIM-PS have great potential and a very wide range of applications in the field of flat plate solar collector.

Integration of Solar Flat Plate Collector and Thermal Energy Storage for Heating Applications: An Experimental Study

Integration of Solar Flat Plate Collector and Thermal Energy Storage for Heating Applications: An Experimental Study

A heating system using flat plate collectors to control the inside greenhouse microclimate in Tunisia

The continuous increase in the level of greenhouse gas emissions and the rise in fuel prices are the main driving forces behind the efforts for more effectively utilize various sources of renewable energy. In many parts of the world and specifically in Tunisia, the direct solar radiation is considered to be one of the most promising sources of energy. Annual sunshine can reach 3288 kWh/m2/year be 6 kWh/m2/day. A greenhouse using means active conventional heating consumes 1 litter of fuel/m2/year which leads to 10 kWh/m2/year. Tunisia surface of greenhouse crops is about 1000 hectares this corresponds to 107 l of foil and 108 kWh .In order to reduce the cost of heating the agricultural greenhouse we used the vacuum solar collectors .Their efficiency depends at the same time upon the ambient climatic conditions and the thermal performances of vacuum solar collectors. Capillary polypropylene exchangers are used to attenuate the differences between the diurnal and nocturnal air temperatures under the tunnel greenhouses. Water circulates in these exchangers at hydraulic closed circuit. In this work we have realized an experimental study of a solar energy heating system. Two types of studies have been done. During the day the suspended exchangers recover the energy in excess for the plants comfort. This recovered energy is stored into the greenhouse ground through the buried exchangers the first one concern the functioning temperature of the heating system installed near the greenhouse and used to heat the water stocked in a tank of 300 litters. In the second type, the energy stored in the ground will be restored through the underground exchangers during the night; thermal energy already stored in the tanks is brought back by the suspended exchangers to heat the air greenhouse. In order to prove the efficiency of our system, we present thermal results relative to the effect of the heater system on the greenhouse microclimate and the agronomic results of the greenhouse culture of tomato. These results are very interesting compared to an unheated greenhouse and had a high effect on tomato quality.

Performance Evaluation and Optimal Design Analysis of Continuous-Operation Solar-Driven Cooling Absorption Systems With Thermal Energy Storage

Abstract A solar absorption cooling system consisting of a flat plate collector, thermal energy storage tank, and absorption chiller is analyzed in this work. A dimensionless model is developed from the energy balance on each component and the chiller’s characteristic performance curves. The model is used to determine the interaction and influence of different parameters such as tank size, solar collector area, chiller size, cooling load, cooling temperature, heat loss, and mass flow rates on the performance. From the analysis, smaller solar collector areas are required for lower cooling loads and smaller tank volumes. A specific cooling load of 1 × 10−5 will require a specific solar collector area between two and six times larger, depending on the initial tank temperature, than the area required for a baseline system that considers typical commercial design and operation parameters. A similar behavior was observed for the specific tank volume. For the baseline system, the minimum specific area of the collector of 9.57 is achieved for an initial tank temperature of 1.19. For a cooling load of 1 × 10−5, the optimum initial tank temperature will be 1.11 that results in a minimum specific solar collector area of 25.26. A specific tank volume of 4 × 10−4 will also have an optimum initial tank temperature of 1.11 that minimizes the specific solar collector area to a value of 28.18. The approach and analysis in this work can be used to determine design parameters for solar absorption cooling systems based on a proper relation among system’s dimensions to achieve optimum operation.

The effect of external and operating conditions on a solar Lithium Bromide absorption chiller

The excessive consumption of fossil energies (electrical energy) during summer caused by the technological development involves more and more climate warming, in order to relieve insistency between electric supply and demand, heat driven absorption chillier is pretty promising, it consists on using heat (solar) as motive energy to provide cold energy. The single effect absorption cycle is the simplest absorption cycle, it’s composed of four main components which are all heat exchangers using a diversity couple of refrigerant. Lithium bromide aqueous solution is one of many others solutions widely used in the absorption chiller for cooling purposes; it possesses several advantages over the other type of absorption systems, such as It highest coefficient of performance compared to other absorption units at the same conditions. A simple flat plat collector can assume the energy required for heating the solution in the generator. Even though, LiBr solution may cause the problem of the crystallization and the limitation of this machine on cooling did not affect the economical aspect of LiBr absorption chiller. The main aim of this article is to study the effect of thermal and environmental parameters each compound of an absorption chiller which produce a cool power equal to 1 kW.

Study of the absorption refrigerating cycle, NH3-H2O coupled with the solar absorption heat transformer, H2O-LiBr by solar data from the City of Oujda (Morocco)

A solar refrigerator is made of a solar collector and a refrigeration system. This paper concerns the study of a two-stage vapour absorption cycle (heat transformer and refrigerating cycle) employing the refrigerant absorbent combinations of H2O-LiBr and NH3-H2O successively. The system consists of coupling the previous absorption cycle so that the first-stage absorber produces heating water to circulate in the generator of the second stage. It is found that the system can be operated at lower hot source temperatures and, thus, it can be supplied either from flat plate collectors.

Comparing Solar Heater Designs: Evacuated Tube Vs. Flat-Plate Collectors

In terms of solar heater designs, this study compares the characteristics of collectors made from evacuated tubes (ETCs) as well as collectors with flat plates (FPCs). Due to their reduced heat loss, ETCs—which have individual tubes made of glass with a sealed under-vacuum double-wall design—perform exceptionally well in colder climates. FPCs, in comparison, are more affordable but less effective since they include a simpler absorbent plate that fits inside of a flat panel. These designs can be implemented using the SolidWorks software, which permits precise 3D modeling as well as simulations. According to research, ETCs are appropriate for colder locations since their vacuum insulation reduces heat loss along maintains greater temperatures. Even while radiation losses make FPCs less efficient, they are still excellent at collecting daylight energy, specifically in warmer climates. Decision-makers looking for sustainable cooling solutions might benefit from analysis that takes into account technical characteristics, financial viability, and geographical compatibility.

The theoretical approach of the solar organic Rankine cycle integrated with phase change material for the Hungarian region

AbstractHungary is not only dependent on imports of natural gas and fossil fuels, but Hungary is also the lowest in renewable energy utilization; otherwise, only 11.3% compared to other Central European countries in renewable energy utilization, above 13%. The percentage of renewables in power generation quadrupled from 8% to 16% between 2010 and 2020, with most of the gains coming from the rapid expansion of solar energy, particularly after 2016. Regarding solar energy resource potential, Hungary has a daily total of around 3.2–3.6 kWh/m2 and a yearly total of about 1168–1314 kW.h/m2. This makes it a suitable location for putting solar thermal collectors in conjunction with an organic Rankine cycle (ORC) system. In this study, the authors analyzed solar thermal as a heat source to generate electricity with ORC using two types of working fluids (R245fa and R123). Hungary's weather data for a whole year is used as primary data to look for solar radiation characteristics and ambient temperature. Based on the general solar collector equation, the parabolic tube collector was selected as the best solar collector to utilize solar radiation by producing a maximum heat of around 654.68 kW. Therefore, the evacuated flat plate collector was selected as the solar collector that can produce the maximum outlet temperature of around 372.15 K with a similar size aperture area. Producing a temperature output from the solar collector for heat transfer in the ORC system and from the performance showed that R245fa resulted in better Wnet performance compared with R123 with values of 45.82 and 28.17 kW, respectively, under the same solar collector. Meanwhile, the material suitable for the thermal energy storage‐evaporator combination is organic phase change material using N‐Octacosane, which in the same temperature range (350–375 K) has the smallest ζ(T) value (1.08–1.103), so the mass required for the system is very efficient.

The thermal impact of stored water as supplementary energy source for a solar air heater

AbstractSolar energy system optimization is a critical consideration for expanding its reach and competitiveness against traditional energy sources. This study specifically targets solar flat plate collectors, focusing on the concept of solar air collectors with an innovative enhancement strategy. To fulfill energy requirements across various applications like heating and drying, setting up collector arrays, such as solar air and water heaters, becomes imperative for meeting desired energy outputs. This research employs numerical analysis to investigate the energy efficiency of a modified solar air heater (MSAH). The enhancement involves integrating a parallelepiped enclosure filled with water, connected to a solar flat plate water collector, into the collector's rear. This water‐filled enclosure serves as a storage tank for the solar water heater. Simulation using the Fluent CFD code is conducted based on meteorological conditions at the Renewable Energy Development Center (CDER) in Bouzaréah, Algeria. Numerical outcomes are compared with experimental findings. Results indicate the positive impact of utilizing the water storage tank as an additional energy source. This modification leads to a substantial 57% performance increase in the MSAH compared with the standard version. This elevated efficiency remains consistent even during periods of reduced solar radiation, owing to the supplementary energy contribution from the solar water heater. In contrast, the standard version's performance hinges solely on available solar radiation for energy generation. This research underscores the potential of combining solar air and water heaters to enhance solar energy systems' efficiency and dependability, facilitating their practical implementation and sustainable utilization.

Numerical analysis of a flat plate collector using different types of parallel tube geometry

To obtain improved thermal performance of flat plate solar collectors, the effect of square and rectangular riser tubes of a flat plate collector (FPC) were numerically investigated and compared with circular riser tube FPC in the present study. For this purpose, a three-dimensional numerical model for FPC collectors has been developed and simulated in CFD software ANSYS FLUENT. Transient thermal performance analysis is carried out to find out the optimum geometrical configuration of the FPC riser tube. The numerical results indicated that using the square-shaped riser tube in FPC improves the collector’s useful heat exchange rate as well as thermal efficiency as compared to the use of circular and rectangular riser tubes. There is a maximum 8.1% higher heat exchange rate of the collector with a square riser tube than a circular riser tube under the same operating conditions. The average efficiency of the collector with the circular tube is 65.95%, whereas the square tube has the highest efficiency of 70.44%. However, the pressure drops through the square and rectangular riser geometry are higher than the circular tube. By making a balance between enhanced heat exchange rate and increased pressure drop, the performance evaluation criterion was evaluated and the square-shaped riser tube having the highest value of 2.65 is better than the other configurations. The results clearly indicate that the collector’s performance is notably influenced by the shape of the riser tube, with a square shape yielding superior performance.

Experimental development, techno-economic and environmental analysis of a hybrid solar space heating system in a subtropical climate

Conventional modes of space heating are expensive and cause greenhouse gas emissions resulting in global warming. In this paper, an experimental analysis of a hybrid solar space heating system consisting of flat plate collectors (FPC) and evacuated tube collectors (ETC) along with a convective radiator is presented. Techno-economic and environmental analysis of the system is performed under real winter conditions in a subtropical climate. The experimental setup is designed such that flat plate collectors and evacuated tube collectors can also be operated separately for comparative analysis with the hybrid system (HC). The experimental results show that ETC achieved a maximum average energy efficiency of 72 % followed by the hybrid collector (HC) and FPC with energy efficiencies of 61 % and 57 %, respectively. The maximum exergy efficiency for ETC, HC and FPC are 54 %, 42 % and 33 % respectively in the month of December with low ambient temperatures. The corresponding maximum sustainability index achieved by ETC, HC and FPC, is 1.76, 1.52 and 1.39 respectively. In addition, the panel radiator achieved a maximum heat gain of 1484 W with an average room temperature in the range of 16.4–24.3 ℃. The economic analysis shows that the benefit-to-cost ratio for the hybrid varies from 0.82 to 1.6 and the payback period varies from 8.9 to 7.41 years compared to the electric heater for an inflation rate of 6–13 %. About 38 % more life cycle cost is observed for electric heater as compared to HSSHS. Environmental analysis reveals that 99 % and 78 % more greenhouse gas emissions are caused by conventional heaters compared to hybrid systems. Thus, a hybrid arrangement of FPC and ETC can be more beneficial for space heating compared to individual installations of these low-temperature solar collectors.