II. DESCRIPTION OF VARIOUS HYBRID PHOTOVOLTAIC THERMAL (HPVT) 2.1. DESCRIPTION OF HYBRID PHOTOVOLTAIC THERMAL (HPVT) AIR COLLECTOR

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1 International Journals of Advanced Research in Computer Science and Software Engineering Research Article June 2017 A Review Paper on Performance Analysis of Various HPVT / PVT Modules under Different Indian Climatic Conditions Sujain Kumar * Devendra Kumar Doda Deepika Chauhan Department of Electrical Engineering, Department of Electrical Engineering, Department of Electrical Engineering, Jaipur National University, Jaipur, Poornima University, Jaipur, Poornima College of Engineering, Jaipur, Rajasthan, India Rajasthan, India Rajasthan, India DOI: /ijarcsse/V7I6/0298 Abstract: Since 1970 s a lot of research and development has been done on various modules of PVT. Many innovative models of PVT has been developed and put forward and validity has been evaluated by experimental data.this paper presents the various performance parameters of different types of modules which include both Air and Water as collector. Effects of various parameters, namely interest rate, life of the system and the maintenance cost have been taken into account. A comparison is made keeping in view the energy matrices. The study has been based on electrical, thermal and energy output of the HPVT air collector. An analysis of an actively cooled combined of photovoltaic thermal system consisting if a linear solar concentrator and tubular absorber has been presented here. An attempt has also been made to evaluate the thermal performance of two types of hybrid photovoltaic thermal (PV/T) air collector system for composite climate of New Delhi. This paper also presents the performance evaluation of a hybrid photovoltaic thermal (Semi transparent PVT) double pass facade for space heating. This paper presents theoretical and experimental analysis of double pass solar air collector with and without porous material. A novel solar air collector of pin-fin integrated absorber designed to increase the thermal efficiency is also discussed here. Keywords: Hybrid photovoltaic thermal (HPVT) air collector, solar air collector, passive and hybrid (PV/T) active solar still, thermal performance, energy and exergy efficiencies. I. INTRODUCTION Increasing cost of fossil fuels has compelled scientists to look for different options to meet energy requirements keeping in view that such options are economical, abundant in nature and have low maintenance cost. Over the years, scientists have studied various options available such as nuclear energy, wind energy, bio mass, fuel cell, solar energy, etc. Studies have shown that amongst available sources of energy, solar energy appears to be freely available, more economical and truly environment friendly than other sources of energy available [1]. Solar energy can be utilized as electrical energy, thermal energy or a combination of both. Hybrid photovoltaic thermal (HPVT) air collector system can collectively generate electrical and thermal energy. The HPVT system can be used as air collector/water collector. A HPVT air collector consists of a PV module with an air duct mounted below the PV module. The air is passed through the duct by using a fan. The air gets heated by using the thermal energy available at the bottom of the PV module. In case of HPVT water collector, water is used in place of air [2]. Thus, an HPVT system can be used as (1) Air collector (2) Water collector II. DESCRIPTION OF VARIOUS HYBRID PHOTOVOLTAIC THERMAL (HPVT) 2.1. DESCRIPTION OF HYBRID PHOTOVOLTAIC THERMAL (HPVT) AIR COLLECTOR [1] Two PV modules, connected in series, are fixed on a rectangular wooden structure. An air duct is provided below the PV module, having an effective area of 0.61 m 2. The entire setup is mounted on a steel frame having the provision to change the inclination of the frame to maximize the solar radiation. Putty and double-side tape is used to avoid leakage of hot air from the duct. The schematic diagram of the experimental setup is shown in Fig. 1a. Details of HPVT air collector are given by Tiwari (2005). The photograph of the system has been shown in Fig. 1b [1,3]. Following estimations have been used in the present paper: (i) Annual electrical, thermal and energy outputs for different solar radiations. (ii) Thermal and energy efficiencies based on above. (iii) Embodied energy of HPVT air collector system. (iv) Energy matrix namely energy payback time (EPBT), electricity production factor (EPF) and the life cycle conversion efficiency (LCCE) for known embodied energy of HPVT air collector. (v) Life cycle analysis in terms of cost/kwh of a HPVT air collector for all given alternatives. (vi) Inlet and outlet air temperature for all the ducts. All Rights Reserved Page 488

2 Fig. 1(a) Schematic diagram of experimental setup, (b) Front view of hybrid photovoltaic (HPVT) system EXPERIMENTAL SETUP OF SOLAR STILL [4] The experimental setup of passive and hybrid (PV/T) active solar stills fabricated, installed and tested at solar energy park at IIT New Delhi are described below. This paper also presents the life cycle cost analysis of the single slope passive and hybrid photovoltaic (PV/T) active solar stills, based on the annual performance at 0.05 m water depth. Effects of various parameters, namely interest rate, life of the system and the maintenance cost have been taken into account. In this paper, annual performance and cost of distilled water produced from newly designed hybrid (PV/T) active and passive solar stills has been carried out in order to estimate the viability of both the systems. The cost payback period and energy payback time (EPBT) considering the initial investment, salvage value, maintenance cost, interest rate and life of the systems into account have also been incorporated. The economics of hybrid (PV/T) active solar still has not been presented by any researchers before. A. Single slope passive solar still The single slope passive solar still of an effective basin area of 1 m 1 m was fabricated by using glass reinforced plastic (GRP) material. The photograph is shown in Fig. 2a. Glasses cover with an inclination of 30 is fixed at the top of the vertical walls of the solar still by using a rubber gasket and clamps. The glass cover is further sealed with window-putty to avoid the leakage of vapours to outside. The distillate output is collected in a channel (trough) fixed at the end of the lower vertical side wall of the basin and taken to outside through a plastic pipe, connected to this channel. The inner surface of the basin is painted black to increase the absorptivity to solar radiation. A plastic hose-pipe is fixed through a hole drilled at the bottom of the basin to drain out the water during cleaning of the basin. Holes are also drilled in the body of the still to fix the thermocouples to measure the temperatures of water in the basin and the inner glass cover. The whole unit is mounted on an angle iron stand. The solar still is oriented due south in order to receive maximum solar radiation throughout the year [4]. Fig. 2(a) Passive solar still All Rights Reserved Page 489

3 B. Single slope hybrid photovoltaic (PV/T) active solar still The photograph of the hybrid (PV/T) active solar still is shown in Fig. 2b. The operating principle of hybrid (PV/T) active solar still involves implementation of following components: - PV integrated flat plate collectors - DC motor pump - Solar still Fig. 2(b) hybrid (PV/T) active solar still Two flat plate collectors are connected in series and integrated to the basin of solar still by means of insulated pipes. The connecting pipes are insulated to avoid thermal losses from the hot water flowing in the pipe to the ambient. Each collector has an effective area of 2 m 2. A glass to glass photovoltaic (PV) module with an effective area of 0.66 m 2 (consists of 36 solar cells and peak power capacity of 75 Wp) has integrated at the bottom of one of the collector at entry side of lower temperature water. Therefore, space and cost of installation of PV module separately from the system has been avoided. In this case, solar radiation is transmitted through non- packing area of PV module and finally absorbed by the blackened absorber [5] GLAZED HYBRID PVT TILE AIR COLLECTOR [7] In the glazed hybrid PVT tile air collector, duct has been placed between tedlar and insulation. The electrical and thermal performance evaluation of glazed PVT tiles air collector has been carried out on various intensity and constant mass flow rate. Analysis has been carried out glazed PVT tile air collector connected in series [6]. Fig. 3(a) Photograph of the solar simulator with glazed hybrid PVT tile connected in series. (b) Orthographic view of glazed hybrid PVT tile air collector connected in series. All Rights Reserved Page 490

4 An experimental testing setup has been designed and fabricated under quasi steady-state condition. The glazed PVT tile consists of a single solar cell (mono crystalline silicon), rated at 2.2 Wp having dimensions 0.12 m length and 0.12 m width has been considered and it has been mounted on a rectangular wooden channel. The channel has dimensions 0.12 m 0.12 m 5 mm. The wooden channel has been sealed with putty and adhesive tape to avoid air leakage. There is provision for the inlet and outlet air to flow through the duct of solar cell under forced mode. For experimentation, outlet of one glazed hybrid PVT tile air collector is connected to the inlet of another similar glazed hybrid PVT tile air collector. The photograph and orthographic view of glazed hybrid PVT tile air collector connected in series have been shown in Fig. (a) and (b), respectively. The air has been flown with the help of small DC fan through the duct of tiles to withdraw the heat associated with base of solar cell. A DC fan of 6.0 V and 0.1 A has been used to circulate the air through the duct [7] V-GROOVE SOLAR AIR COLLECTOR [8] The solar air collector performance evaluation is important for optimal sizing of collectors and the drying system for a given task. Although indoor performance evaluation is easier and quicker, it is desirable to test the solar air collectors under outdoor conditions. It is difficult to simulate the real environment in an indoor facility. An outdoor test facility was constructed according to the guidelines of ASHRAE [9]. Fig. 4. V-groove air collector The test facility consisted of two modules, namely, the collector and the air-handling module. The collector had the facility to change angle of inclination, which was set at 10 for the present study. Collector temperature and pressure measurements were made in rigid duct sections close to the collector similar to that recommended by ASHRAE [10] PHOTOVOLTAIC THERMAL SYSTEM CONSISTING OF A SOLAR CONCENTRATOR AND TUBULAR ABSORBER [11] Here idea is to reduce the unit cost of electricity produced by solar cells and also to collect a significant amount of thermal energy output from the same system. A typical system of this kinsd consists of a concentrating device which illuminates an absorber surface, providing higher fluxes as compared to the incident solar flux. Linear solar concentrators are preferred in such applications, owing to their relatively simple tracking requirements and ease of fabrication. A variety of absorber shapes have been used with linear solar concentrators for thermal applications [11]. Fig. 5. Cross section view of tubular absorber mounted with solar cell All Rights Reserved Page 491

5 2.6. PERFORMANCE ANALYSIS OF A DOUBLE-PASS THERMOELECTRIC SOLAR AIR COLLECTOR [12] A double-pass TE solar air collector has been developed and tested by C. Lertsatitthanakorn et al. The TE solar collector was composed of transparent glass, air gap, an absorber plate, thermoelectric modules and rectangular fin heat sink. The incident solar radiation heats up the absorber plate so that a temperature difference is created between the thermoelectric modules that generates a direct current. Only a small part of the absorbed solar radiation is converted to electricity, while the rest increases the temperature of the absorber plate. The ambient air flows through the heat sink located in the lower channel to gain heat. The heated air then flows to the upper channel where it receives additional heating from the absorber plate [12]. Fig. 6. Schematic diagram of Double pass solar air collectore 2.7. PERFORMANCE OF A DOUBLE-PASS SOLAR AIR COLLECTOR [13] Double pass counter flow solar air collector with porous material in the second air passage is one of the important and attractive design improvement that has been proposed to improve the thermal performance. This paper presents theoretical and experimental analysis of double pass solar air collector with and without porous material. A mathematical model has been developed based on volumetric heat transfer coefficient. Effects of various parameters on the thermal performance and pressure drop characteristics have been discussed. Fig. 7. Double pass solar air collector The experimental set up has been designed, fabricated and tested outdoor for data collection. Two solar air collectors identical in design have been used in order to compare the performance. In the double pass arrangement collector consists of two passages; first passage is formed between the two glass covers and the second passage where in air flows in the reverse direction is formed between the bottom glass cover and the absorber plate. In one collector the second passage is filled with porous absorbing material (black painted wire mesh) where as the second passage of the other collector has been kept empty [13] PERFORMANCE STUDY OF A NOVEL SOLAR AIR COLLECTOR [14] Pin-fin arrays solar air collectors were covered by a single, high transmittance glazing with 4 mm thick, dimension size of mm, which was to reduce the convective and long wave losses to the atmosphere. Heat losses to environment from the sides and from the bottom of collector were minimized by good thermal insulation, namely 50 mm and 70 mm polystyrene sheet respectively. The absorber of pin-fin arrays solar air collectors is a blackened stainless steel sheet of 1 mm with mm size and is integrated with iron pin-fins of 4 mm diameter in the flat plate [14]. All Rights Reserved Page 492

6 Fig. 8. Novel Air collector III. RESULT AND DISCUSSION Table (a) Annual thermal and exergy efficiency of HPVT air collector for different insolation levels. Table (b) Annual energy outputs for different climatic conditions. It is evident from above table that the electrical, thermal and exergy outputs for the climatic conditions of Jodhpur are the best when compared with other climatic conditions covered in the study due to higher insolation and sunshine hours. However, an annual thermal and exergy efficiency is highest for Srinagar due to low operating temperature of PV module. It is evident that the electrical, thermal and exergy outputs for the climatic conditions of Jodhpur are the best when compared with other climatic conditions covered in the study due to higher insolation and sunshine hours. However, an annual thermal and exergy efficiency is highest for Srinagar due to low operating temperature of PV module. Fig. 9 shows the effect of maintenance cost on the distilled water obtained from experimental and proposed designs of the solar stills for an expected systems life of 15 years and 30 years, respectively. The 10% increase in cost per kg (CPK) has been estimated with an increase in maintenance cost from 5% to 15%, irrespective of the systems life. The cost of production of the distilled water decreases in linearity with increase in the system life. The figure also reveals that the lowest costs obtained for the proposed passive and hybrid active solar stills are Rs. 0.70/kg and Rs. 1.94/kg, respectively. Fig. 10 shows the variation the cost (CPK) of distillate obtained from the passive and hybrid (PV/T) active solar stills with respect to interest rate for a fixed maintenance cost of 10% and for different systems life (15 and 30 years). It has been estimated that the cost per kg (CPK) of distillate obtained from passive solar still increases almost 1.7 times with the increase of interest rate from 4% to 12%. All Rights Reserved Page 493

7 Fig. 9. Variation of cost per kg (CPK) of distilled water with respect to their designed life (n), at different maintenance cost (M s ), capital cost (P s,exp, and P s,com ) and for fixed interest rate(i=4%), (a) passive and (b) hybrid (PV/T) active solar still. Fig. 10. Variation of cost per kg (CPK) of distilled water obtained from (a) passive and (b) hybrid active solar still for different designs (Experimental and proposed ) with respect to rate of interest (i) and system life (n) at fixed 10% maintenance cost (M s ). All Rights Reserved Page 494

8 The experimental results of outlet air temperatures for both cases (case-i and case-ii) at various intensities 600 W/ m 2, 700 W/ m 2 and 800 W/ m 2 have been shown in Fig.11. It has been observed that outlet air temperature for case-ii is higher as compared to case-i at the same intensity, constant mass flow rate and Tfi = 38 C. It can be seen that solar cell temperature for case-ii is significantly higher than case-i at lower intensity (600 W/ m 2 ) but at higher intensity (700 and 800 W/ m 2 ) as shown in Fig.12. the solar cell temperature of both cases are nearly same. Fig. 11. Variations of outlet air temperature at various intensity. Fig. 12. Variations of solar cell temperature at various intensity. Fig. 13 shows the efficiency curves at different flow rates. From the figure, it can be seen that, as flow rate increases, efficiency increases considerably. The reason for the significant increase in efficiency from kg/ m 2 s to kg/ m 2 s can be attributed to changes in flow condition from laminar to turbulent. Fig. 14 shows the collector efficiency for wide range of flow rates. Simulation result show that efficiency increases constantly with flow rate up to kg/ m 2 s and, thereafter, increases at a decreasing rate. The curve tends to be flat after flow rate of 0.05 kg/ m 2 s. Fig. 13. Efficiency curves for different flow rates Fig. 14. Variation of g and To with airflow rate. All Rights Reserved Page 495

9 Fig.15 shows the variation of the coolant outlet temperature and the temperature of the solar cells along the length of the tubular absorber. Also plotted in the same figure are the amounts of overall electrical and thermal outputs for various absorber lengths. As expected, the coolant and solar cell temperatures increase more or less exponentially along the length of the absorber. Consequently, both the electrical and thermal outputs increase linearly up to a certain length of the absorber, and for larger lengths, the gain in the power outputs is nominal. Fig. 15. Variation of electrical power, thermal power, coolant output temperature and the solar cell temperature along the length of a tubular absorber. S Fig. 16. Temperature variations along the length of collector (with porous material).h All Rights Reserved Page 496

10 Above fig. 16 shows the temperature variation of glass covers, first air pass, second air pass, matrix absorber and absorber plate along the length of collector. It is seen that there is a substantial rise in air temperature compared to conventional collector as well as double pass counter flow collector without porous material. It is also seen that the temperature different between the porous material and air is less compared to the temperature difference between the absorber plate and air in case of collector without matrix as well as for the conventional collectors. It is further observed that the temperature of first air pass is higher in case of double pass counter flow solar air collector without matrix compared to double pass collector with matrix, where as in the second pass due to porous material there is a substantial rise in air temperature compared to collector without matrix. Fig. 17. Variations of incident solar radiation, ambient temperature, average air temperature of outlet heat sink and collector (air flow rate kg/s, 6 June 2007) IV. CONCLUSIONS AND RECOMMENDATIONS (1) For a variation in solar radiation in the range W/ m 2, the thermal and exergy efficiency drop by about 10% and 5%, respectively. (2) Amongst the climatic conditions covered under the study, Jodhpur is the best for use of hybrid photovoltaic thermal (HPVT) air collector. (3) The distilled water cost obtained from the hybrid (PV/T) active solar still is found to be 2.8 times than the passive solar still. For commercial use in remote areas, the cost of distilled water obtained from hybrid (PV/T) solar still could be acceptable when compared to water transportation and selling the water at higher rate to avoid the financial risk. (4) The Payback periods of the passive and hybrid (PV/T) active solar stills are obtained in the range of years and years, respectively, for the selling price of distilled water in the range of Rs. 10 to Rs. 2/kg. Therefore, passive solar stills are acceptable for potable use. (5) It can be concluded that if the number of glazed PVT tile are connected in series then it will be more beneficial from overall energy and overall exergy point of view. (6)This new present setup would have beneficial effect of permitting much less expensive installation for testing and development. Hence the test procedure can be used by manufacturers for testing of different type of PV tiles and combination of PV tiles in order to optimize its products for better efficiency. (7) A v-groove collector is 12% more efficient than a flat plate collector of similar design. (8) As flow rate of kg/ m 2 s provides good efficiency and outlet temperature sufficient for most agricultural drying applications, this flow rate can be considered optimum for this collector configuration. (9) The TE solar collector technology provides a solution to improving the energy yields per unit surface area of a solar collector. The TE solar air heater approach is particularly suitable for most agricultural drying applications. (10) Double pass counter flow solar air collector with porous material in the second air passage is one of the important and attractive design to improve the thermal performance. (11)Thermal performance of double pass solar air collector with porous absorbing material is 25% higher than that of double pass solar air collector without porous absorbing material and 35% higher than that of single pass collector. RECOMMENDATIONS (1) The present studies for hybrid PVT technology should be integratedinto building for space heating for the cold climatic condition for field testing; (b) into solar dryer for crop drying. (2) The proposed theoretical model may be used for predicting the output power of the TE modules with reasonable accuracy given temperature difference conditions. All Rights Reserved Page 497

11 REFERENCES [1] Raman, V., Tiwari, G.N., Life cycle cost analysis of HPVT air collector under different Indian climatic conditions. Energy Policy 36, pp [2] Tiwari, A., Sodha, M.S., Chandra, A., Joshi, J.C., Performance evaluation of a photovoltaic thermal solar air for composite climate of India. Solar Energy Materials and Solar Cells 90, pp [3] Agrawal, B., Tiwari, G.N., Life cycle cost assessment of building integrated photovoltaic thermal (BIPVT) systems. Energy and Buildings 42, pp [4] Kumar Shiv,. Tiwari G.N., Life cycle cost analysis of single slope hybrid (PV/T) active solar still, Applied Energy 86, pp [5] Kumar, S., Tiwari, A., An experimental study of hybrid photovoltaic thermal (PV/T) active solar still. Int J Energy Res 32, pp [6] Solanki, S.C., Dubey, S., Tiwari, A., Indoor simulation and testing of photovoltaic thermal (PV/T) air collectors. Applied Energy 86, pp [7] Agrawal, S., Tiwari, G.N., Pandey, H.D., Indoor experimental analysis of glazed hybrid photovoltaic thermal tiles air collector connected in series. Energy and Buildings 53, pp [8] Karim, M.A., Hawlader, M.N.A., Performance evaluation of a v-groove solar air collector for drying applications. Applied Thermal Engineering 26, pp [9] Methods of testing to determine thermal performance of solar collectors, ASHRAE STANDARD 93-97, ASHRAE, 345 East 47 th Street, New York, NY 10017, [10] J.E. Hill, J.P. Jenkins, D.E. Jones, Testing of Solar collectors according to ASHRAE standard 93-77, ASHRAE, Trans. 84 (1978), [11] Sharan, S.N., Mathur, S.S., Kandpal, T.C., Analysis of a combined photovoltaic thermal system consisting of a linear solar concentrator and a tubular absorber. Energy Converts 27, pp [12] Lertsatitthanakorn*, C., Khasee, N., Atthajariyakul, S., Soponronnarit, S., Therdyothin, A., Suzuki, R.O., Performance analysis of a double-pass thermoelectric solar air collector. Solar Energy Materials & Solar Cells 92, pp [13] Ramani, B.M., Gupta, A., Kumar, R., Performance of a double pass solar air collector. Solar Energy 84, pp [14] Peng*,D., Zhang, X., Dong, H., Lv, K., Performance study of a novel solar air collector. Applied Thermal Engineering 30, pp [15] Singh, H.N., Tiwari, G.N., Monthly performance of passive and active solar stills for different Indian climatic conditions. Desalination 168, pp [16] Joshi, A.S., Tiwari, G.N., Monthly energy and exergy analysis of hybrid photovoltaic thermal (PV/T) system for Indian climate. International Journal of Ambient Energy 28, pp [17] Tiwari, A., Sodha, M.S., Performance evaluation of hybrid PV/thermal water/air heating system. Renew Energy 31, pp [18] Agrawal, S., Tiwari, G.N., Energy and exergy analysis of hybrid micro-channel photovoltaic thermal module. Solar Energy 85, PP All Rights Reserved Page 498