Effect of Surface Conditions and Tilt Angle of Solar Photo- Voltaic Panel on Power Output

Transcription

1 Effect of Surface Conditions and Tilt Angle of Solar Photo- Voltaic Panel on Power Output Harmanpreet Singh M. Tech. Student Department of Electrical Engineering GZSCCET, Bathinda (Punjab) Sarbjeet Kaur Bath Professor & Head Department of Electrical Engineering GZSCCET, Bathinda (Punjab) ABSTRACT Solar energy is a source of clean, non-polluting electricity. Unlike conventional power plants, solar plants emit no pollutants or greenhouse gases. So today government as well as private sectors prefers to produce large amount of electricity with solar plants. Our main aim of the present investigation is to study the factors influencing the efficiency of solar photovoltaic system. Large amount of solar energy is freely available on earth but its usage is limited due to a number of factors. So it is decided to study the major factors responsible for it; tilt angle of solar panel and cleaning of solar panel are two prominent factors that greatly affects the efficiency of solar panel. The cost analysis of solar energy generated with cleaning of soiled panels after a normal period of 4 days and daily cleaning of soiled panels has also been carried out. After successful completion of study, an optimum plan can be formulated for practical set ups which can lead to maximum efficiency of solar power generation. Keywords Solar energy, tilt angle, soiling, efficiency. 1. INTRODUCTION The use of conventional resources for production of electricity also poses a serious threat to environment and human life. Mainly used conventional resources are coal, petroleum, etc., which caters majority of human energy requirements. Also these resources are a non-renewable resource, which means they will expire in relatively short interval of time. [1] So there is great urgency to look for better alternatives. The substitution to the non-renewable resources is the promotion of renewable resources like sunlight, wind, biomass, flowing water, geothermal energy, etc. Most of the renewable sources of energy depend on sunlight in one way or other. Wind and hydroelectric power are possible due to the direct of heating of the Earth s surface which leads to difference in atmospheric pressure, which further leads to movement of air from higher to lower pressure area and results in wind of varying velocities. Solar energy is the conversion of sunlight into electricity, heat or thermal energy using panels or collectors. [2] Other renewable energies which do not depend on sunlight are geothermal energy, which is the heat from the Earth, and tidal energy which is conversion energy of tides into electricity. Solar energy is radiant light and heat from the Sun that is harnessed using a range of latest technologies such as solar heating, photovoltaic cells, solar thermal energy and artificial photosynthesis. Solar techniques used now a days includes the use of photovoltaic systems, concentrated solar power and solar water heating to harness the energy of sunlight. Solar energy is an important renewable energy source for the country, both in the generation of PV electricity and as heat. Therefore, it is necessary to quantify the solar potential of an area, but to achieve this goal requires an adequate estimation of solar radiation incident on the Earth's surface. Generally, the spatial variability of solar radiation is determined by chronological, geographical, atmospheric and surface conditions. 232

2 2. LITERATURE REVIEW Several authors, in the past, have studied the various aspects of solar power generation with the help of different techniques. A study to determine the optimum tilt angle for installing photovoltaic solar panels in Zomba district, Malawi, has been conducted. The study determined the optimum monthly tilt angles of PV solar panels and the seasonal adjustments needed for the panels in order to collect maximum solar radiation throughout the year. In this study, global solar radiation data was used to determine the daily and monthly optimum tilt angles for the PV panels. For fixed solar panels with no seasonal adjustments, the optimum tilt angle for the PV solar panels that are northfacing has been determined to be 25. [3] In another study, a numerical approach was adopted to calculate the solar radiation on sloped planes by integrating the measured sky radiance distributions. The annual total solar yield at different sloped surfaces facing various orientations and monthly solar radiations at the optimal tilt surface and three vertical planes facing east, south, and west were determined. The energy outputs, efficiencies, environmental benefits and cost implications were also considered. [4,5] In a study, an attempt was made to optimise the collection of solar energy within the period of its availability in order to increase its utilisation through appropriate determination of optimum solar collector tilt angles. Fundamental solar radiation equations were programmed to determine optimum tilt angles in locations within latitudes 1 and 14. Graphs obtained from latitude 6 and 13 data were analysed to investigate solar radiation on some tilt angles. The optimum tilt angles for solar heating for periodic tracking of the sun in the region within latitudes 1 and 14 were predicted. The results of this work confirmed that solar radiation on tilted surface increases with latitude. [6,7] Observations of solar power were recorded for finding the optimum tilt angle for the month of May & June in Jaipur. The experimental result shows that at different position of solar panel, there is different power & hence efficiency. From the observed data, it was concluded that the optimum tilt angle for May is 5-10 and for June it is 5 2. [8] The key contributions to the understanding, performance effects, and mitigation of power loss due to soiling on a solar panel were evaluated in terms of electrical characteristics. The result shows that soft shading affects the current provided by the PV module, but the voltage remains the same. In hard shading, the performance of the PV module depends on whether some cells are shaded or all cells of the PV module are shaded. If some cells are shaded, then as long as the unshaded cells receive solar irradiance, there will be some output although there will be a decrease in the voltage output of the PV module. This study also present a few [9, 10] cleaning method to prevent from dust accumulation on the surface of solar arrays. For the first time, novel nanodome solar cells, which have periodic nanoscale modulation for all layers from the bottom substrate has been demonstrated. These devices combine many nanophotonic effects to both efficiently reduce reflection and enhance absorption over a broad spectral range. Nanodome solar cells with only a 280 nm thick hydrogenated amorphous silicon (a -Si:H) layer can absorb 94% of the light with wavelengths of nm. The nanodome devices have a power efficiency of 5.9%, which is 25% higher than the flat film control. Also the nanodome devices when modified with hydrophobic molecules present a nearly super hydrophobic surface and thus enable self-cleaning solar cells. [11] In the field conditions, a thick layer of dust gets accumulated on the surface of solar panels. It significantly affects the performance of photo-voltaic module. With this dust, the irradiated area of the panel gets reduced and panel becomes partially irradiated, resulting in rise of temperature of module. For every single degree rise in temperature, power efficiency gets reduced by 0.5%. [12] 3. POWER OUTPUT FROM SOLAR PHOTO-VOLTAIC SYSTEM Sunlight is composed of photons of solar energy. These photons contain various amounts of energy corresponding to the different wavelengths of the solar spectrum. When photons strike a photovoltaic cell, 233

3 they may be reflected, pass right through, or be absorbed. Only the absorbed photons provide energy to generate electricity. When enough sunlight energy is absorbed by the semiconductor material, it causes generation of significant number of free electrons in the crystal. Special treatment of the material surface during manufacturing makes the front surface of the cell more receptive to free electrons, so the electrons naturally migrate to the surface. When the electrons leave their position, holes are formed. When many electrons, each carrying a negative charge, travel toward the front surface of the cell, the resulting imbalance of charge between the cell's front and back surfaces creates a voltage potential like the negative and positive terminals of a battery. When the two surfaces are connected through an external load, electricity flows. [13] 4. PROBLEM FORMULATION Solar panels result out be most efficient one, when sun rays are incident at perpendicular angle them. The generally default value taken in routine is a tilt angle equal to the latitude of location of plant plus 15 in winter, or minus 15 in summer. A little variation in tilt angle can lead to drastic change in solar power output for large solar plants. So it requires optimisation of orientation of solar panel in accordance with the latitude of the location. Also in the summer season, sunlight is available in abundance in Punjab. But there are also frequent sandstorms in Punjab in this period before the arrival of monsoon. The accumulation of dust on solar panels will result in quite sharp decrease in power output from solar panels, as the panel surface will not be effectively exposed to Sun rays as in the case of cleaned panel. So it was planned to study the effect of both these factors on solar panel efficiency and record the data accordingly so as to arrive on any conclusion. 5. METHODOLOGY The proposed study of determining dependence of efficiency of solar photo-voltaic system on tilt angle and surface of solar panel was carried out in the following order of steps. Firstly, the effect of tilt angle on solar plant s efficiency was studied. For this purpose, for different set of tilt angles of solar panels, the energy generated by solar photovoltaic system was noted down from Solar plant, Banwala (Sri Muktsar Sahib) maintained by Azure Power Limited and efficiencies of different tilt angles with time was calculated. Then the effect of soiling of solar panel on its efficiency was studied. For this purpose, the energy generated with two different set of daily cleaned and uncleaned (cleaned after a period of 4 days) modules was noted down from Solar plant, Banwala (Sri Muktsar Sahib) maintained by Azure Power Limited and then efficiency corresponding to each case was calculated. Also cost analysis of solar energy generated with the above two sets of data arising due to soiling phenomenon was carried out. From the above analysis, the monetary benefits of solar energy generation with chosen factors according to our study can be calculated for any period of time and for any number of solar panels. 6. RESULTS AND DISCUSSION In this section, we will proceed to data generated from Solar plant, Banwala for 3 periods of cleaning and for different tilt angles of solar panels and further the results so obtained will be discussed. 6.1 Effect of Soiling A foremost requirement to the design of solar-based conversion systems is the knowledge of optimum orientation conditions and tilt surface at which maximum solar energy can be collected. In the Table 1, the data for a period of 11 days is shown in the month of April. 234

4 From Table 1, it is clear the there is net loss of money if solar panels are daily cleaned instead of a routine cleaning cycle of 4 days. This is due to the cost factors accounting for the charges of water arrangement including its transport. So in brief, we can say that although it is clear from the above table that there is greater power generation with daily cleaning of panels as soiling leads to decrease in efficiency of solar panel, but still it is not economically favourable. Day Generation (Daily Cleaned) Table 1. Power generation data with daily cleaned and cycle cleaned panels Generation (in (Cleaned as per cycle) Generation Loss Per Inv Cost per Unit (in Rs.) Revenue (in Rs.) Cleaning Cost per rack (in Rs.) Cleaning Cost per panel Net profit/ loss (in Rs.) Source: Azure Solar plant, Banwala From Fig. 1, the difference in power generation due to soiling clearly indicates the significance of cleaning of solar panel surface Generation (Daily Cleaned) Generation (Cleaned as per cycle) Figure 1. Effect of soiling on power generation. 235

5 6.2 Effect of tilt angle The power generation for three tilt angles of 0, 10 and 20 was recorded and the results are as shown in the Table 2. From Fig. 2, it is clear that there is large change in power output for the different set of angles. This is due to the fact that for different tilt angles, the amount of solar energy incident on panel varies with angle and hence there is variation in output. Day Table 2. Power generation for different tilt angles of solar panel 0 tilt generation 10 tilt generation 20 tilt generation Difference between 10 and 0 output (in Difference between 20 and 10 output (in Difference between 20 and 0 output (in Source: Azure Solar plant, Banwala tilt generation 10 tilt generation (in 20 tilt generation (in Figure 2. Effect of tilt angle on power generation. 236

6 Solar power is set to play an increasingly significant part in future energy system of India. Solar energy is a free and most importantly a renewable resource. So, it does not matter how much of solar energy is used today, there will be still the same power supply in the future. ACKNOWLEDGEMENT The authors would like to thank field staff and management of Azure Power Limited for their cooperation in successful completion of research work. REFERENCES [1] [2] [3] Kamanga, B., Mlatho, J. S. P., Mikeka, C., Kamunda, C Optimum Tilt Angle for Photovoltaic Solar Panels in Zomba District, Malawi. Solar Energy, 1-9. [4] Li, D. H. W., Lam,T. N. T Determining the Optimum Tilt Angle and Orientation for Solar Energy Collection Based on Measured Solar Radiance Data. J. Photo., 1-9. [5] Khoo, Y. S., Nobre, A., Malhotra, R., Yang, D., Reindl, T., Ruther, R., Aberle, A. G Optimal Orientation and Tilt Angle for Maximizing in-plane Solar Irradiation for PV Applications in Singapore. J. Photo., 4, [6] Zhu, J., Hsu, C. M.,Yu, Z.,Fan. S., Cui, Y Nanodome Solar Cells with Efficient Light Management and Self- Cleaning. Nano Lett.,10, [7] [8] Kumar, S.,Chaurasia, P. B. L., Singh, H. K., Experimental Study of Optimum Tilt Angle for Solar PV Panel in Jaipur (Rajasthan). Sci. Resear. 3, [9] Maghami, M. R.,Hizam,H., Gomes, C., Radzi, M. A., Rezadad, M. I., Hajighorbani, S Power loss due to soiling on solar panel: A review. Ren. Sustain. Energy Rev., 59, [10] Yadav, A. K., Chandel, S. S Tilt Angle optimization to maximize incident solar radiation: a review. Ren. Sustain. Energy Reviews, 23, [11] Idowu, O. S., Olarenwaju, O.M., Ifedayo, O. I Determination of optimum tilt angles for solar collectors in low-latitude tropical region. Energy Environ. Eng. 4, [12] Kumar, S., Kaur, T Solar PV Performance-Issues and Challenges, Innov. Resear. Elect. Electro. Instru. Cont. Eng. 2, [13] Lin, C Case Study of Solar Power Producing Efficiency from a Photovoltaic System. Energy Effici., 4,