Energy and exergy analysis of a hybrid photovoltaic thermal double pass air collector

In this paper an attempt has been made to analyze the performance of semi transparent hybrid PVT double pass air collector. Based on the first law of thermodynamics, energy balance equations are for-mulated to derive the analytical expression for air temperature at the outlet, as a function of the design and climatic parameters for investigating the performance of semi transparent hybrid PVT air collector. The analysis is based on quasi-steady state condition. This paper shows the detailed analysis of energy and exergy of a semi transparent hybrid PVT double pass air collector and its comparison with single pass air collector for four weather conditions (a, b, c and d type) for five different cities (New Delhi, Bangalore, Mumbai, Srinagar, and Jodhpur) of India. It has been analyzed that if such systems are installed only at 10% of the total residential houses in Delhi, then the total carbon credits earned by the system is found to be Rs. 1767 millions in terms of thermal energy and Rs. 493 millions in terms of exergy for double pass air collector whereas Rs. 1528 millions in terms of thermal energy and Rs. 446 millions in terms of exergy for single pass air collector. The results clearly shows that hybrid PVT double pass air collector have better performance as compared to single pass air collector.     

Energy and exergy analysis of hybrid micro-channel photovoltaic thermal module

In this communication, an attempt has been made to evaluate energy and exergy analysis of a hybrid micro-channel photovoltaic thermal (MCPVT) module based on proposed micro-channel solar cell thermal (MCSCT) under constant mass flow rate of air in terms of design and climatic parameter. The performance in terms of overall annual thermal and exergy gain and exergy efficiency of micro-channel photovoltaic thermal module have been evaluated by considering four weather conditions for different climatic conditions of India. Further analysis has also been carried out for single channel photovoltaic thermal (SCPVT) module and the results of micro-channel photovoltaic thermal module and single channel photovoltaic thermal module have been compared.On the basis of numerical computations, it has been observed that an overall annual thermal and exergy gains have been increased by 70.62% and 60.19% respectively for MCPVT module for Srinagar climatic conditions. Similar observations have been made for Bangalore, Jodhpur and New Delhi.     

Exergy analysis of integrated photovoltaic thermal solar water heater under constant flow rate and constant collection temperature modes

In this communication, an analytical expression for the water temperature of an integrated photovoltaic thermal solar (IPVTS) water heater under constant flow rate hot water withdrawal has been obtained. Analysis is based on basic energy balance for hybrid flat plate collector and storage tank, respectively, in the terms of design and climatic parameters. Further, an analysis has also been extended for hot water withdrawal at constant collection temperature. Numerical computations have been carried out for the design and climatic parameters of the system used by Huang et al. [Huang BJ, Lin TH, Hung WC, Sun FS. Performance evaluation of solar photovoltaic/thermal systems. Sol Energy 2001; 70(5): 443–8]. It is observed that the daily overall thermal efficiency of IPVTS system increases with increase constant flow rate and decrease with increase of constant collection temperature. The exergy analysis of IPVTS system has also been carried out. It is further to be noted that the overall exergy and thermal efficiency of an integrated photovoltaic thermal solar system (IPVTS) is maximum at the hot water withdrawal flow rate of 0.006 kg/s. The hourly net electrical power available from the system has also been evaluated.     

Overall thermal energy and exergy analysis of hybrid photovoltaic thermal array

In this paper, overall thermal energy and exergy analysis has been carried out for different configurations of hybrid photovoltaic thermal (PVT) array. The hybrid PVT array (10.08 m × 2.16 m) is a series and parallel combinations of 36 numbers of PV modules. A one-dimensional transient model for hybrid PVT array has been developed using basic heat transfer equations. On the basis of this transient model, an attempt has been made to select an appropriate hybrid PVT array for different climatic conditions (Bangalore, Jodhpur, New Delhi, and Srinagar) of India. On the basis of high grade energy (i.e. overall exergy gain), case-III has been selected as the most appropriate configuration because overall exergy for case-III is 12.9% higher than case-II. The overall thermal energy and exergy gain for Bangalore is 4.54 × 10⁴ kW h and 2.07 × 10⁴ kW h respectively which is highest in comparison to the other cities.     

Exergoeconomic analysis of glazed hybrid photovoltaic thermal module air collector

In this paper, an exergoeconomic analysis has been carried out and on the basis of this analysis it has been concluded that in terms of energy saving the glazed hybrid photovoltaic thermal (PVT) module air collector offers a greater potential compared to PV module. The experimental validation for glazed hybrid PVT module air collector has also been performed and it has been observed that there is a good agreement between the theoretical and experimental values with correlation coefficient in range of 0.96–0.99 and root mean square percentage deviation in range of 2.38–7.46. The experiments have been carried out on clear days during the month July 2010 to June 2011. For the validation of theoretical results with experimental results, a typical day of winter month (December 08, 2010) and summer month (April 11, 2011) has been considered. An experimental uncertainty for December and April month is 11.6% and 2.1% respectively. The annual overall thermal energy and exergy gain are 1252.0 kWh and 289.5 kW h respectively. The annual net electrical energy savings by glazed hybrid PVT module air collector is 234.7 kW h.     

Energy matrices analyses of hybrid photovoltaic thermal (HPVT) water collector with different PV technology

In this paper, an attempt has been made to evaluate and compare the energy matrices of a hybrid photovoltaic thermal (HPVT) water collector under constant collection temperature mode with five different types of PV modules namely c-Si, p-Si, a-Si (thin film), CdTe and CIGS. The analysis is based on overall thermal energy and exergy outputs from HPVT water collector. The temperature dependent electrical efficiency has also been calculated under composite climate of New Delhi, India.It is observed that c-Si PV module is best alternative for production of electrical power. Maximum annual overall thermal energy and exergy is obtained for c-Si PV module. The maximum and minimum EPBT of 1.01 and 0.66 years on energy basis is obtained for c-Si and CIGS respectively, whereas on exergy basis maximum EPBT of 5.72 years is obtained for a-Si and minimum of 3.44 in obtained for CIGS PV module. EPF and LCCE increase with increasing the life time of the system.     

A hybrid amorphous silicon photovoltaic and thermal solar collector

A hybrid amorphous silicon (a-Si) photovoltaic and thermal solar collector was developed and its performance tested. The solar cells, deposited on glass panels and having an average efficiency of 4% and a total area of 0.9 m², were bonded to the fin and tube aluminum heat-exchange plate using simple technology. This hybrid unit performed well as a thermal solar collector, heating water up to 65°C, while the electric characteristics of the photovoltaic modules showed little change. In addition to saving space this integral unit substantially reduces the balance-of-system cost of the photovoltaic generator. The transmission of light through various layers of an a-Si cell was measured and, in order to improve the thermal efficiency, a novel transparent type of a-Si cell was developed and tested in the hybrid unit. The results obtained show that it is possible to construct simple and cheap hybrid systems having good photovoltaic as well as thermal efficiencies.     

Optimization of a solar photovoltaic thermal (PV/T) water collector based on exergy concept

In this paper, the optimization of a solar photovoltaic thermal (PV/T) water collector which is based on exergy concept is carried out. Considering energy balance for different components of PV/T collector, we can obtain analytical expressions for thermal parameters (i.e. solar cells temperature, outlet water temperature, useful absorbed heat rate, average water temperature, thermal efficiency, etc.). Thermal analysis of PV/T collector depends on electrical analysis of it; therefore, five-parameter current–voltage (I–V) model is used to obtain electrical parameters (i.e. open-circuit voltage, short-circuit current, voltage and current at the point which has maximum electrical power, electrical efficiency, etc.). In order to obtain exergy efficiency of PV/T collector we need exergy analysis as well as energy analysis. Considering exergy balance for different components of PV/T collector, we obtain the expressions which show the exergy of the different parts of PV/T collector. Some corrections have been done on the above expressions in order to obtain a modified equation for the exergy efficiency of PV/T water collector. A computer simulation program has been developed in order to obtain the amount of thermal and electrical parameters. The simulation results are in good agreement with the experimental data of previous literature. Genetic algorithm (GA) has been used to optimize the exergy efficiency of PV/T water collector. Optimum inlet water velocity and pipe diameter are 0.09 m s⁻¹, 4.8 mm, respectively. Maximum exergy efficiency is 11.36%. Finally, some parametric studies have been done in order to find the effect of climatic parameters on exergy efficiency.     

Experimental study on a new hybrid photovoltaic thermal collector

A calorific energy is generated during the photovoltaic conversion of the solar module which increases the temperature of the cell and will causes a fall of its electric output. This phenomenon is due, on one hand to the partial unabsorptive solar radiation which constituted the origin of the cells heating and on the other hand, with the Joule effect caused by the passage of the photo electrical current generated in the external circuit. This heating, harmful for the photovoltaic cells output involved many research efforts to limit its effects by evacuating this heat. There was also the idea to exploit this phenomenon by the combination of the photovoltaic module with a thermal system to form the photovoltaic-thermal hybrid collector (PVT) which will generate at the same time electricity and heat. In this paper we described the design of a new type of PVT collector through its experimental study. This novel collector constitutes a new technical approach to maximize the total output of conversion with lower cost compared to the traditional hybrid collectors.     

Performance analysis of a hybrid photovoltaic thermal double pass air collector using ANN

This paper presents the use of artificial neural network for performance analysis of a semi transparent hybrid photovoltaic thermal double pass air collector for four weather conditions (a, b, c and d type) of New Delhi. The MATLAB 7.1 neural networks toolbox has been used for defining and training of ANN for calculations of thermal energy, electrical energy, overall thermal energy and overall exergy. The ANN model uses ambient air temperature, global solar radiation, diffuse radiation and number of clear days as input parameters for four weather conditions. The transfer function, neural network configuration and learning parameters have been selected based on highest convergence during training and testing of network. About 2000 sets of data from four weather stations (Bangalore, Mumbai, Srinagar, and Jodhpur) have been given as input for training and data of the fifth weather station (New Delhi) has been used for testing purpose. It has been observed that the best transfer function for a given configuration is logsig. The feedforward back-propagation algorithm has been used in this analysis. Further the results of ANN model have been compared with analytical values on the basis of root mean square error.     

Modelling of a hybrid photovoltaic thermal collector based on CdTe

A few years ago, silicon photovoltaic panels had yields of 10 to 18%, which made them interesting because is not profitable enough (too expensive to energy conversion yield too low).But recently, thin film technology appears to increase the efficiency and reduce the cost. For application in hybrid collectors, various types of solar photovoltaic hybrid collectors (PVT) based on new materials for solar cells have been developed as the binary semiconductor, ternary and quaternary materials and organic. CdTe is a the most appropriate binary materials for use in photovoltaic structures in thin layers, this material can produce a high yield of about 15% and is also known by a direct band structure gap of a value of 1.45 eV and a very high absorption coefficient (>105 cm^–1 in the visible). In this work we present the modeling of a hybrid photovoltaic thermal collector based on the thin films solar cells of CdTe, and then we made the determination of the temperature levels of the various layers through the development of the energy balance sheet involves heat exchange between the different components of the collector and to study its electrical and thermal performance, and finally compare their efficiency with it of the PVT collector based on monocrystalline silicon.     

Energy and exergy efficiencies of a hybrid photovoltaic–thermal (PV/T) air collector

In this communication, an attempt has been made to evaluate exergy analysis of a hybrid photovoltaic–thermal (PV/T) parallel plate air collector for cold climatic condition of India (Srinagar). The climatic data of Srinagar for the period of four years (1998–2001) has been obtained from Indian Metrological Department (IMD), Pune, India. Based on the data four climatic conditions have been defined. The performance of a hybrid PV/T parallel plate air collector has been studied for four climatic conditions and then exergy efficiencies have been carried out. It is observed that an instantaneous energy and exergy efficiency of PV/T air heater varies between 55–65 and 12–15%, respectively. These results are very close to the results predicted by Bosanac et al. [Photovoltaic/thermal solar collectors and their potential in Denmark. Final Report, EFP Project, 2003, 1713/00-0014, www.solenergi.dk/rapporter/pvtpotentialindenmark.pdf].     

Conceptual design of a hybrid thermal and photovoltaic receiver of an FMDF collector

The optical characteristic of a Fixed Mirror Distributed Focus (FMDF) solar collector is used as a basis for the design of an hybrid thermal and photovoltaic (PV) receiver. The result provides another variation in energy conversion that an FMDF solar collector can conveniently perform.     

Experimental investigation of a copper sheet-laminated solar photovoltaic thermal water collector

Different concepts and designs of photovoltaic thermal (PV/T) collectors were developed for the past few decades to improve the electrical and thermal efficiencies. Several of those designs have become successful and are being commercialized along with other solar collectors. This paper discusses the experimental studies on a novel PV/T water-based collector constructed by laminating the PV cells on a copper thermal absorber. This modification reduced the thermal resistance by 9.93 %, thereby enabling better heat transfer from the PV cells to the heat transfer fluid. Water was passed through a single water channel connected to an open reservoir. Experiments were conducted with and without glazing, with two different water mass flow rates and stagnant conditions, and with load and no-load conditions and thermal stress test. Results show that an overall efficiency of 87.52 % was achieved in the presence of glazing at a mass flow rate of 0.1 kg/s. Few conformance tests according to IEC standards are also presented to check the electrical insulation and structural integrity of the PV/T collector.     

Effect of hybrid nanofluids mixture ratio on the performance of a photovoltaic thermal collector

Solar photovoltaic-thermal (PV/T) collectors, are hybrid collectors used to convert solar radiation into usable thermal and electrical energy. Recently, the field of research on PV/T is has focused on improving the efficiency of the PV/T collector by replacing the conventional heat transfer fluids (HTFs) with nanofluids. This article investigates the effect of hybrid nanofluids mixture ratio on the useful energy and overall efficiency of a PV/T collector operating with Al₂O₃-ZnO water nanofluid as the HTF. Experiments to measure the thermophysical properties of the hybrid nanofluids were conducted for various temperatures, volume concentrations, and mixture ratios, furthermore, accurate correlation models were proposed. Metrological data and energy output readings collected from the PV solar farm at Cyprus International University were used to validate our model. The study observed that at the optimum mixture ratio (0.47 of Al₂O₃ in the hybrid), the electrical, thermal, and exergy efficiencies of the PV/T collector are 13.8%, 55.9%, and 15.13% respectively. Also, the cell temperature drops by 21% when the mass flow rate is 0.1 kg/s as compared to when it is 0.01 kg/s. Finally, the study concludes that by using the Al₂O₃-ZnO hybrid nanofluid an overall peak thermal efficiency of 91% can be attained, and this represents a 34% enhancement in the collector's performance when compared to water.     

Performance analysis of a hybrid photovoltaic/thermal (PV/T) collector with integrated CPC troughs

In the present investigation a theoretical analysis has been presented for the modelling of thermal and electrical processes of a hybrid PV/T air heating collector coupled with a compound parabolic concentrator (CPC). In this design, several CPC troughs are combined in a single PV/T collector panel. The absorber of the hybrid PV/T collector under investigation consists of an array of solar cells for generation of electricity, while collector fluid circulating past the absorber provides useful thermal energy as in a conventional flat plate collector. In the analysis, it is assumed that solar cell efficiency can be represented by a linear decreasing function of its temperature. Energy balance equations have been developed for the various components of the system. Based on the developed analysis, both thermal and electrical performance of the system as a function of system design parameters are presented and discussed. Results have been presented to compare the performance of hybrid PV/T collector coupled with and without CPC. Copyright © 1999 John Wiley & Sons, Ltd.     

Advancement in solar photovoltaic/thermal (PV/T) hybrid collector technology

This article presents an overview on the research and development and application aspects for the hybrid photovoltaic/thermal (PV/T) collector systems. A major research and development work on the photovoltaic/thermal (PVT) hybrid technology has been done since last 30 years. Different types of solar thermal collector and new materials for PV cells have been developed for efficient solar energy utilization. The solar energy conversion into electricity and heat with a single device (called hybrid photovoltaic thermal (PV/T) collector) is a good advancement for future energy demand. This review presents the trend of research and development of technological advancement in photovoltaic thermal (PV/T) solar collectors and its useful applications like as solar heating, water desalination, solar greenhouse, solar still, photovoltaic-thermal solar heat pump/air-conditioning system, building integrated photovoltaic/thermal (BIPVT) and solar power co-generation.     

Feasibility study of a hybrid photovoltaic/thermal collector system in the climate of Jordan

This study is dedicated to investigating the feasibility of photovoltaic/thermal (PV/T) collectors' technology for application in Jordan. Simple parallel-plate collector configurations were simulated using COMSOL: rectangular fins, triangular fins, and wavy walls. The wavy-wall configuration was found the most efficient alternative in terms of heat transfer with respect to the pumping power and performance factor that took into account the comparison with a plain-wall parallel-plate collector. However, the performance of the plain-wall parallel plate preceded that of the wavy wall by increasing the Reynolds number and the water channel height. The plain-wall parallel-plate configuration was further investigated on HOMER as a 5 MW solar plant that provides energy to a 5-MW facility. One MW of its load is direct thermal load. Different solar plant designs were compared. The PV/T plant was found to be very much energy saving but not feasible due to its high initial cost. However, the PV/T plant was better than the PV when the cooling was not complete compromising on some electric energy in favor of heat generation. Further work on reducing the cost of the PV/T collector is required especially with regard to contact methods between the PV and the absorber plate and to the weight of the collector.     

Energy integration of methane's partial-oxidation in supercritical water and exergy analysis

In this work, we examined the exergy losses of reaction pathways that have been reported in the literature in the context of an integrated methanol production and electrical power flow sheet. Three reaction pathways were examined: (i) complete oxidation, (ii) partial oxidation to produce only methanol, and (iii) partial oxidation to produce methanol and carbon monoxide. The latter was based on experimental data reported for reactions in supercritical water. It was found that there were optimum feed ratios that minimized reactor heat requirements and maximized electrical work output. An exergy analysis showed that the largest irreversibilities occurred in the reactor itself and that the partial oxidation of methane to produce methanol and carbon monoxide gave reactor irreversibilities that were lower than for the total oxidation reaction pathway. Conversion of methane to methanol and carbon monoxide in supercritical water can be accomplished by supplying only chemical exergy.     

Comparative study based on exergy analysis of solar air heater collector using thermal energy storage

This communication presents the comparative experimental study based on energy and exergy analyses of a typical solar air heater collector with and without temporary heat energy storage (THES) material, viz. paraffin wax and hytherm oil. Based on the experimental observations, the first law and the second law efficiencies have been calculated with respect to the available solar radiation for three different arrangements, viz. one arrangement without heat storage material and two arrangements with THES, viz. hytherm oil and paraffin wax, respectively. It is found that both the efficiencies in case of heat storage material/fluid are significantly higher than that of without THES, besides both the efficiencies in case of paraffin wax are slightly higher than that of hytherm oil case. Copyright © 2011 John Wiley & Sons, Ltd.