Pico-Hydro and Photovoltaic Co-Generation System with Effective Cooling Technique

Transcription

1 Pico-Hydro and Photovoltaic Co-Generation System with Effective Cooling Technique Dr. S. Allirani Associate Professor/EEE Sri Ramakrishna Engineering College, Coimbatore, India E.Sneha UG Scholar/ EEE Sri Ramakrishna Engineering College, Coimbatore, India. ABSTRACT: The solution for the existing energy demands and conservation of non-renewable energies could be put up simultaneously, with effective use of the abundant solar energy. The rate of conversion of this energy into useable power could be enhanced by adopting efficient cooling methods of the panel. This paper presents the idea of an effective cooling method using water, which is circulated through a channel. The channel, itself is then constructed into a Pico-Hydro power generation system. This paper proposes a perception to combine solar and hydro power generation system, in addition to the cooling system. 1. INTRODUCTION One of the most important forms of renewable energy is the solar photovoltaic energy. A solar cell converts a part of incident solar light into electrical energy, the rest being wasted as heat with no hazardous pollutants being emitted. The demand for solar energy has increased by 20 to 25 percent over the past twenty years [1]. There are various factors that affect the efficiency of a solar cell. Cell temperature and energy conversion efficiency are some of them [4]. The solar panels are kept in the sunlight for a long duration of time. This results in over heating of the panel surface and hence reduces the light absorbing efficiency. The electrical efficiency will decrease when the operating temperature of the PV (Photo Voltaic) module increases. Therefore decreasing the temperature of PV module can boost the electrical efficiency. Generally, some techniques, like air cooling and water cooling are employed to cool the PV module to maintain lower operating temperature [5]. To improve the performance of the cell, the 405 Dr. S. Allirani, E.Sneha temperature should be maintained within the Maximum Allowable Temperature (MAT). To utilize the available renewable energy sources effectively, the cooling of the panel can be done through Pico hydro power system. Since the two non-conventional energy resources (solar and hydro power) are combined, this becomes a Co- Generating system. The main ideation has been taken from the Canal top project which was implemented in Gujarat, across the Narmada river by Prime Minister of India Narendra Modi [3]. In the literature referred in [6], the efficiency of solar panels is increased by cooling the panel by spraying water on the surface. Both water and air cooling techniques has been studied and found that water cooling is more effective than air cooling. The power output was found to be considerably higher when the panel was cooled with water. The idea of combining two renewable energy systems is imbibed from the research paper published by Nuramalina Bohari et al [7]. The Panel cooling technique equipped with the Pico-Hydro system is described in Chapter II. It is followed by Chapter III, with experimental setup along with the design and construction of Picohydro system. It also consists of the comparison tables before and after the employment of the cooling technique on the solar panel, with various parameters. Chapter IV presents results and the efficiency calculation, followed by conclusion.

2 II. PANEL COOLING & PICO-HYDRO SYSTEM A Pico hydro setup shown in Fig. 1 Fig.1 Block diagram of panel cooling and Pico-hydro system is typically run-of-the-river, meaning that dams are not used but rather pipes divert some of the flow, drop this down a gradient, and through the turbine before returning it to the stream. Pico hydro plants are suitable for pumped storage systems. In pumped storage, at times of low electrical demand, the excess generation capacity is used to pump water into the higher reservoir. When the demand becomes greater, water is released back into the lower reservoir through a turbine [2]. 2.1 Cooling Module The main idea of the system is cooling of solar panel. The set up for cooling consists of a solar panel with copper tubes clamped behind it. Water, which acts as the coolant is made to flow through the copper tube. Since these tubes are in direct contact with the solar panel, they result in significant cooling when water is passed through it. The cooling of solar panel will have a good impact on effective absorption rate of the solar panel (i.e) the temperature of the panel is inversely proportional to its absorbing capacity. Thus the cooling block ensures high conversion rate of solar radiation. 2.2 Pico-Hydro System Large hydropower provides electrical power for industry and domestic use, small-scale hydro is 406 Dr. S. Allirani, E.Sneha making some contributions toward providing this basic need to remote and off-grid areas especially in developing countries. Pico hydro is hydro power with a maximum electrical output of five kilowatts (5kW). Common examples of devices which can be powered by Pico hydro are light bulbs, radio and televisions. Normally, Pico hydro power system is found in rural or hilly areas. III. EXPERIMENTAL SETUP OF THE SYSTEM Fig.2. Shows the Snapshot of the Electrical hardware setup. This set up is introduced to utilize the power generated by the co-generation system to any other external applications. It consists of a microcontroller, boost converter and an inverter. The supply for the load can be taken from the inverter. Water from the main tank is given to a turbine through a DC pump. The DC pump increases the pressure of the water to a considerable value such that the turbine rotates and produces mechanical energy. This mechanical energy is thus converted into electrical energy. The generated power is stored in a battery. The water flowing out from the turbine is stagnated in a reservoir. From the reservoir the water is pumped through a DC pump. Fig.2 Prototype of Experimental Setup of Cooling module & Pico-Hydro System Copper tubes are bent and clamped behind the solar panel according to its size. The pumped water is circulated through the copper tubes. This eventually reduces the temperature of the panel and thus increases the performance of the solar panel. After cooling the panel the hot water is recycled

3 back to the main tank. The output from the panel is stored in the same battery. The battery is connected to the voltage regulator which gives a regulated output to the controller circuit. The PIC controller is used to generate PWM pulses for the boost converter. The boost converter boosts the voltage to an optimum value to run the load. The load used here is a single phase induction motor. 3.1 Design and Construction of Pico-hydro system Generally the higher the water drop (head pressure) is, the lower the required water volume flow is for the same power output. The equation that can be used to model a hydroelectric plant can be expressed as Where, P is the output power in W Q is the flow rate in cubic meters per second h is the drop height in meters E is the efficiency in percentage Water velocity at the turbine can be calculated by Where, g is the acceleration due to gravity (9.81 m/s 2 ) h is the height of the water drop in meters Pen-stock pipe area, From that equation the diameter of the pen-stock pipe is The assumption for the high pressure system is that the desired output should be 514W and that the height of the water source is at 150m. The efficiency is conservatively set at 75%. Hydro-power equipment is normally divided into three groups, high pressure, medium pressure and flow rates are low, medium and high. High pressure system includes a pipe line (pen-stock) and usually a "Pelton" type wheel. A Pelton wheel is an impact driven device. A Pelton wheel has buckets which the high pressure water stream strikes causing it to rotate which turns the attached generator producing electricity. Pelton wheels are normally used where the height of the water drop exceeds 70 meters. Pelton wheels are 80-90% efficient. A Pelton wheel turbine controls generator output by restricting water flow from a high pressure nozzle. Medium pressure hydroelectric generators use Kaplan, Francis or Turgo turbines. Francis and Kaplan wheels are called reactive devices because they are driven by water passing over them. These turbines are used from meters water drop. They use what are called "wicket gates" to control the water entering the turbine. They are somewhere in the neighborhood of 90% efficient in converting the potential energy of the water to shaft rotational energy supplied to the generator. Some of the equipment used for low pressure systems includes a reverse Archimedes screw, a water wheel or a bulb turbine set in a river. A paddle wheel in a river can produce significant electrical energy. These types of hydroelectric generators can produce energy for water drops well less than 10 meters. Efficiencies range from 65% to 85% Effect of cooling on Solar Panel Solar panels in full sun can easily reach temperatures of 54 degrees Celsius and above. Those temperatures lead to efficiency loss and shorten the lifespan of the panels by breaking them down more quickly. A significant solution for this problem is to cool the panel. The cooling technique results in improving the efficiency of output power by reducing the cell temperature. Initially the output voltage and current from a 75W solar panel was measured using multimeter without cooling. And the output power was also calculated. Again the same process was repeated with cooling by pouring water over the panel [8]. The output parameters were measured and tabulated. 407 Dr. S. Allirani, E.Sneha

4 Table 3.1 Panel parameters before cooling S.No. Time Temperature :35 1:00 1:15 1:30 1:45 2:00 ( C) 43.4(B) 38.6(F) 45.4(B) 40.4(F) 44.7(B) 39.4(F) 42.8(B) 38.5(F) 43.0(B) 38.1(F) 41.3(B) 37.9(F) It was found that the output voltage and current has been improved considerably when the panel was cooled. The tabulated readings are shown in Table 3.1. and Table EXPERIMENTAL RESULTS & DISCUSSIONS The panel parameters were measured on two consecutive days at the same time of the day. The readings have been tabulated in the Table.4.1 and Table.4.2. On the first day the measurements were taken without the cooling system. The second day the readings were taken by including the cooling module. Table 4.1.Performance of System without Cooling S.No. Time (hours) Power (W) 7. 2: (B) 40.2(F) S. No. 8. 2: (B) 37.4(F) *B-Panel Back **F Panel Front Table 3.2 Panel parameters after cooling Time Temperature ( C) 46.0(B * ) 46.0(F ** ) 42.4(B) 41.8(F) 44.8(B) 44.2(F) 43.2(B) 42.4(F) 48.8(B) 48.2(F) 50.2(B) 47.0(F) 53.8(B) 50.2(F) 52.8(B) 47.4(F) Dr. S. Allirani, E.Sneha

5 Table 4.2 Performance of System with Cooling S.No. Time (hours) Power (W) Graphical interpretations The graphical representations of voltage and current waveforms are shown in Fig.4.1 and Fig Efficiency Calculations Length of each solar cell = 3cm Breadth of each solar cell = 2cm Area of each solar cell = 3*2= 6 cm 2 Number of solar cells in the panel = 36 So, Total area of solar panel = Number of solar cells x Area of each cell = 36*6 = 216 cm 2 Irradiance to solar panel = 806 lux 1 lux = 1.46e -7 W/cm 2 Therefore, 806 lux = W/cm 2 Input power = Irradiance * area of the solar panel = * 216 = W Fill factor (FF) = Before cooling the solar panel: Fill factor = 0.3 Power output = * FF = 8.32 * * 0.3 Power input = W Efficiency of the panel = = = % After cooling the solar panel: Power output = * * 0.3 Power input = W Fig.3 Vs. Time before Cooling Efficiency of the panel= = =37.669% Improvement in efficiency after cooling: = 7.621% From the experiments done, it was proved that the efficiency of the solar panel has been improved by 7.621% after the implementation of the cooling technique. Fig.4. Vs. Time before Cooling 5. CONCLUSIONS From the graph shown in Fig.5.1 and Fig.5.2, it is clear that the performance of the solar panel has 409 Dr. S. Allirani, E.Sneha

6 been improved considerably after cooling. As a result, both the output parameters-current and voltage has been increased. The system is efficient because there is no wastage of any resources used and the photoelectric conversion rate is also very high. The lifespan of the solar panel is increased by the process of cooling. Since both the systems use renewable resources for generation of power, no fossil fuels are required. In addition to this, there is no emission of toxic gases into the atmosphere. References 1. Bhubaneswari Parida, Iniyan, S. and RankoGoi (2010) A Review Of Solar Photovoltaic Technologies, Renewable and Sustainable Energy Reviewspp Dave, S.K., Ashokkumar, A. Parmar, Ankit, P. Shah, Nikhil, M. Vyas (2011) Pico Hydro Power Generation: Renewable Energy Technology For Rural Electrification, International Journal Of Advanced Research In Engineering Science And Management Mikio Taguchi, Ayumu Yano, Satoshi Tohoda, Kenta Matsuyama, Takeshi Nishiwaki, Kazunori Fujita, and Eiji Maruyama (2014) 24.7% Record Efficiency Hit Solar Cell On Thin Silicon Wafer, IEEE Journal of PhotovoltaicsVol.4, No.1,pp Mohamed Musthafa, M. (2015) Enhancing Photoelectric Conversion Efficiency of Solar Panel by Water Cooling, Journal Of Fundamentals of Renewable Energy and Applications Vol Moharram, K.A., Abd-Elhady, M.S., Kandil.H.A. and El-Sherif, H. (2013) Enhancing The Performance Of Photovoltaic Panels By Water Cooling, Ain Shams Engineering Journal, pp Nuramalina Bohari, Wan Azlan, Wan Zainal Abidin, Martin Anyi, Dayang Nur Salmi and Dharmiza Awang Salleh (2015) Micro-Hydro/Solar Hybrid System Framework for Off-Grid Application, Journal of Applied Science & Process Engineering Vol Saurabh Mehrotra, PratishRawat, Mary Debbarma and Sudhakar, K. (2014) Performance Of A Solar Panel With Water Immersion Cooling Technique, International Journal of Science, Environment and Technology Vol. 3, pp Dr. S. Allirani, E.Sneha