PERFORMANCE OF PV PANELS

Akash A L , BharathKumar S , Charankumar ,Deepak R Patil ,Hanamanta Patil

Abstract

This paper presents the result of a literature survey focused on performance of PV panels. The main goal of this paper is to provide information to the engineers, industrialists and researchers who are interested on PV panels and to emphasize PV panels as a promising alternative replacement for fossil fuels. Since the use of energy has become an integral part of our life, its supply should be secure and sustainable. The energy requirement of the world is ever increasing. The increasing energy demands put a lot of pressure on the conventional energy sources. Therefore, there is a need for alternative energy sources which can provide us energy in a sustainable manner.

The obvious choice of a clean energy source, which is abundant and could provide security for the future development and growth, is the sun’s energy.Pv panels in that regard have been most efficient energy convertors hence study of them is of utmost importance in order to utilize them efficiently.

Introduction

Photovoltaic technology is developing rapidly. Photovoltaics are increasingly being incorporated in to the construction of new buildings for generating electrical power . photovoltaic system uses solar cells to convert energy from sun radiation into electricity. In this paper we will study about How will efficiency of building pv panels affected by the air flow. And the temperature of pv panels also affect the performance. To minimise that temperature pv panels are attached with HP water cooling system. And To maximize energy collection in pv panels, we will study in this paper how to orient photovoltaic modules towards the equator with an optimal tilt-angle from the horizon.

Energy efficient design and sustainable use of resources are current and future requirements for the development of new technologies. The most effective and the easiest in application is photovoltaic technology which can be implemented as Building Attached Photovoltaic or Building Integrated Photovoltaic. The second technology is more cost effective since the traditional covering and finishing building materials can be substituted by PV panel. That solution gives dual functionality to PV panels, as they are both structural components and energy production devices. The efficiency of photovoltaics varies with temperature. A method for improving the temperature of photovoltaic panels by using the air and passive cooling is studied in this papers. Solar photovoltaic (PV) system uses solar cells to convert energy from sun radiation into electricity.

Principle

Experimentation

Soteris A.kalogirou et al[1] .Mathematical model to formulate heat exchange process between air flow and the pv panel .we use basic heat transfer equations. Same equation can be used for the heat transfer in solids and provided that u=0 the convective term is set to zero.In the boundary between the pv panel and air gap heat flows from hotter panel to the stream of air, while at the air-wall boundary the hotter air transfer heat to the wall. finally at the external wall boundary heat is lost to the environment.

For the numerical set up, consol multiphysics software has been used in 2D.Comsol software can freely choose time steps, according to the calculated error, which can reduce computational memory and time.

Chen Hongbinga,*, Chen Xilina, Li Sizhuoa [2]. The testing rig of the PV/HP water heating system is made up of PV/HP collector, water circulating pump, water tank and flow meter. Fig. 1 shows a cross-section view of part PV/HP collector. The PV panel is fixed on to the metal sheet 1mm thick, serving as an absorber plate, through a thin adhesive layer. Ten heat pipes are connected to the metal sheet, which forms the fins of the heat pipes for the enhancement of heat transfer from PV panel to heat pipes. The heat pipes, 8/7 mm of external/internal diameter for each one, are arranged at equal spacing of 75 mm throughout the panel width. The condensation end of heat pipes are inserted into the manifold, which is connected to circulating pump and water tank in series. The edges and back surface of the PV/HP collector are covered with insulation material to reduce heat loss. The total aperture area and PV cell area are 1.24m2 and 1.17m2, respectively. The PV panel consists of 36 PV cells, made of polycrystalline silicon. The PV panel is connected to a rheostat for the testing of power output under various loads and the peak power output is determined at the resistance of 15 Ω. Under the radiation of 1000 W/m2 and the ambient temperature of 25 oC, the PV panel has an open circuit voltage of 31.0 V and a short circuit current of 8.73 A. The peak power output is 200 W with an electrical efficiency of 16.13%.

Guihua Li 1,2, Runsheng Tang 1,*, Hao Zhong[3]. Daily collectible radiation on fixed south-facing solar panels with a tilt-angle, 0 β, from the horizon can be calculated by summing the contribution of the beam radiation, the component of sky diffuse radiation, and the radiation reflected from the ground as follows

Knowing time variations of Ib, Id and Ih in a day, the daily collectible radiation on fixed, full 2-axis and HA-tracked panels could be calculated by numerical integration over the day, then annual solar gain can be simply obtained by summing daily collectible radiation in all days of a year. A reasonable estimation of daily collectible radiation on a fixed or tracked surface should be done based on the monthly global and diffuse radiation on the horizon obtained from the observations over many years. However, the monthly diffuse radiation is not always available in many places, and the most widely used and available data in solar calculations is the monthly horizontal radiation.

Vijay Talekar and Vikram Shinde [4] carried out the experiment order to determine the performance of the biaxial solar tracking PV panel with collector in comparison with a

regular position PV panel (45 degree in south direction) without collector. The two PV panels were subjected to the same solar radiation conditions at the same time and the energy output of each panel was monitored and tabulated. For experimentation they have used a Solar panel of 6 volt 5 watt Capacity and have taken reading of Voltage and Current produced by the panel.The readings are taken with respect to corresponding angles when Panel was at 45 degree placed without collector and Panel normal to the sun rays without collector and Panel normal to the sun rays with collector.

. Tanima bhattacharya[5] experimented on temperature and wind effects on pv panels. A digital multimeter is used to measure the short circuit current and open circuit voltage. One digital thermometer has been used to check the ambient temperature, anemometer to measure wind speed, and TENMARS TM -207 solar power meter to measure the intensity of the solar radiation and the output energy is calculated for four cases using different temperature, namely 400c, 450c, 550C,650c. The solar PV panel is left to overheat till the MAT is reached in each case, and then, the panel was cooled to the normal operating temperature ad this cycle is repeated for 180 min.

K.A. Moharram[6] has made a cooling system which consists of six main parts as follows:-Six PV modules of 185 W peak-output each ,Aluminum water tank of 0.3 m3 capacity,120 water nozzles for spraying water over the panels,Drain pipe for collecting the water and return it back to the tank. The water pump sucks the water from the middle of the water tank via a suction pipe to avoid sucking any dust. The suction pipe consists of a non-return valve and a strainer to avoid sucking of large particles that could damage the water pump. The sucked water passes through the water filter, and then, it is sprayed over the PV modules for cooling.

Concentrating rays Biaxial Tilting Mechanical pair[4]

The setup which has been used to obtain the experimental results consists of two photovoltaic panels arranged as shown in Figure below

1) A first panel (left panel as panel A) is in normal conditions to be used as a reference.

2) The other panel (panel B) has been placed above a steel plate, with an air channel underneath the panel, varying in spacing (Figure 1(a)).

With the result obtained from this configuration , we can analyse, on the one hand, the panel behaviour when it is placed on the steel roof of an industrial building and, on the other hand, the influence of the temperature depending on the space between both surfaces.

Panel temperature at different points, voltage, and current are measured in order to understand the panel behaviour under normal operating conditions and to compare it with those of panel B, which is modified to test different ducts with different cross-sections. In this second panel, panel temperature at different points, voltage, and current are also measured together with the air temperature and the air flow rate through the channel.

To study the influence of panel temperature and the aspect ratio of the air channel on the panel performance, several experimental cases have been made for different configurations of the panels

Y.M.Irwan, W.Z.Leow, M.Irwanto, Fareq.M, A.R.Amelia, N.Gomesh, I.Safwati[10]. Solar simulator is very helpful in the solar energy experimental. This is because many scientific experiments can be simulated and performance of PV panel is studied under controllable indoor test facility. The DC water pump is attached on the front side of the PV panel to spray water over the surface of PV panel. Solar simulator is set up on a steel frame with the dimension is 183 cm by 183 cm by 183 cm is used to lift all the halogen lamp bulbs and can be moved horizontally. Twenty units of halogen lamps (Philips Halogen 500 W) with built in reflector is attached on the solar simulator. Two units of 50W Monocrystalline PV panels are used. PROVA 200 solar module analyzer was used to measure the performance of both PV panels with and without water cooling mechanism.

Jayashree A. Gotmare, Dr. S. V. Prayagi[11]. This experimental set‐up was designed to investigate how the temperature affects the efficiency and power output of PV panel during operation. it is composed of two similar but separate PV solar photovoltaic panels each with area of 0.351 m2. The maximum output voltage and current are 17.7V, 2.09A respectively

and with maximum power output of 37W at irradiance of 1000 w/m2 and cell temperature of 25°C. One of the panels is modified by attaching the small water bags at the backside of the panel. The other panel is a conventional PV as a reference panel. The photovoltaic panels are positioned east west. The panels tilt angle are set to 21 deg with respect to the horizontal, which is the local latitude of Nagpur (Latitude 21.1500 N, Longitude 79.0900°E), India, so as to face in the south direction. Sensors (model PT100) were installed at the top & back side of both the PV panel in order to measure the photovoltaic panels’ temperature. The experiments were conducted from 9.00 am to 3.00 pm for 15 days & recorded the data for every 5 min.

Xiao Tang, Zhenhua Quan, Yaohua Zhao [12]. A silicon solar panel was used in this experiment, with its peak efficiency in the range of 10-15% under standard condition (25°C, 1000 W/m2), peak power of 10 W and an area of 0.0625 m2. The solar panel should face the south with a tilt angle of 45°. Its total radiation area was 0.2049 m2. The air-cooling solar panel has evaporator section of the heat pipe was adhered to the back of the solar panel with its length of 283 mm and width of 300 mm. The condenser section was exposed to the air with its length of 200mm and width of 300 mm.

The schematic of the water-cooling solar panels has evaporator section of the heat pipe was adhered to the back of the solar panel with its length of 283 mm and width of 285 mm. The condenser section was adhered to a water flume with its length of 40 mm and width of 285 mm. The specs of water flume and water tank are 40 × 25 × 385 mm and 280 × 280 × 280 mm, respectively. There is a distance of 170 mm between them.

Anna Machniewicz*, Dominika Knera, Dariusz Heim [13]. It is assumed that the whole surrounding partitions of the room – except for the external wall – was defined as an internal with the same parameters of indoor conditions. The ventilated cavity between external wall and PV panels is 0.1 m deep. In the analysis it is assumed that phase change material will be closed in 2 cm thick aluminum honeycomb structure sealed between two aluminum plates. Four paraffin waxes with different transition temperatures were considered. Thermal

conductivity of PCMaluminum structure was recalculated, taking into account properties of both materials, and equaled 12 W/m·K.

Cătălin George Popovici, Sebastian Valeriu Hudișteanu*, Theodor Dorin Mateescu, Nelu-Cristian Cherecheșa [14]. The ribs of the heat sink have circular holes of 0.003 m radius, placed at a distance of 0.03 m one to another. These holes intend to improve the air circulation near the heat sink and to extract more heat from the PV panel. The minimum size of the cell in the interest domain is about 0.002 m for the heat sink and ribs, and about 0.008 m for the air channel. The velocity of the air behind the photovoltaic panel was set at 1.5 m/s.

Shaharin Anwar Sulaimana, Atul Kumar Singhb, Mior Maarof Mior Mokhtara, Mohammed A. Bou-Rabeec [15]. The experiment test rig comprising a solar photovoltaic panel , a set of spotlight and the electrical circuit system. The solar panel module comprised arrays of silicon mono-crystal cells. The number of spotlights and their positions were varied depending on the requirements of experiments. Preliminary tests were performed at different conditions to determine the suitable number of spotlights that could result in acceptably homogeneous radiation of light energy over the panel area. It is observed that with the use of six spotlights, the magnitude of the light radiation increased and became close to natural light condition. The suitable distance between the spotlights and the solar PV panel was also studied by varying the distance and followed by measurements of light radiation intensity.

3. OBERSVATIONS:

Soteris A.kalogirou, Lazaros Aresti , Paul christodoulides , Georgia florides[1].To run the program the various parameters were adjusted according to a real case scenario. equations describing the solar radiation falling on the PV panel were derived for a typical day in June in Cyprus and used for three vertical surfaces facing east, south and west. In the simulations it was assumed that 85% of the falling radiation is converted to heat, whereas the other 15% is converted into electricity that is the usual efficiency of polycrystalline silicon solar cells.

Chen Hongbinga,*, Chen Xilina, Li Sizhuoa[2]. The testing was carried out at Beijing University of Civil Engineering and Architecture, China. The experimental rig was placed on the roof of Building No. 2 with PV/HP collector exposed to sunshine directly not being in shade. PV/HP collector was regulated to be 45o. The pyranometer was mounted at the same tilt surface beside PV panel to measure the solar radiation on the front surface of PV panel. Adhesive thermocouples were pasted on the front surface of PV panel for monitoring temperature variation. Two probe type thermocouples were installed at the inlet and outlet of manifold for measuring water temperature. The water circulation was driven by water pump and the flow rate was controlled by valve regulation. Three thermocouples were installed at different depth of water tank to measure water temperature.

Guihua Li 1,2, Runsheng Tang 1[3]. In a specific site, the annual collectible radiation on a full 2-axis tracked panel is largest as compared to fixed or single-axis tracked panels, and is a constant statistically over many years, but the annual solar gain on a traditional fixed south-facing panel, S0, is a function of its tilt-angle, and an optimal tilt- angle, opt 0, β , could be obtained by repeatedly calculating S0 for different tilt-angles until a maximum annual

collectible radiation, S0,max, is found. For HA-tracked solar panels, the annual solar gain, Sha, is a function of the orientation angle, φ , of the sun-tracking axis. In the consequent calculations, the time step, dt, for the numerical calculation of daily solar gain is taken to be 60 seconds, the steps of 0 β for finding their optimal values were set at 0.1o, the albedo of the ground was taken to be 0.22, and monthly horizontal radiation data used in this work was obtained by averaging monthly measurements from 1971 to 1999 in 34 sites of China.

Hrushikesh Swami,Abhishek Shete[4]observed that system gives maximum amount of power generated due to the biaxial motion and also total cost of tilting and tracking mechanism is less than the 25% that of cost of panel required to generate the same power.It produced 2.5 times more power than regular position of the solar panel. And the construction of mechanism is very simple and handling of the system is very easy. The designed tracker for sun rays is found worked efficiently. The bi-axial tracking system was found effective than single axis tilting mechanism.

Kaushik Pal [5] observed that as the ambient temperature increased solar module efficiency was also increased signifying that ambient temperature had direct proportion with solar module efficiency. It was also seen from this figure that the correlation between the module efficiency and ambient temperature/wind speed is nonlinear.

H.A. Kandil[6] observed that It is possible to cool and clean the PV panels using the pro-posed cooling system in hot and dusty regions and the cooling rate for the solar cells is 2 LC/min based on the concerned operating conditions, which means that the cooling system will be operated each time for 5 min, in order to decrease the module temperature by 10 LC. The PV panels yields the highest output energy if cooling of the panels starts when the temperature of the PV panels reaches the maximum allowable temperature 45o.

When the space of the air channel underneath panel B is smaller, the temperature difference between panel A and panel B is higher, up to 8–10°C at high irradiance, due to panel B being less cooled by natural convection and its performance is much worse. However, for the measured highest aspect ratio, the experimental results show that the maximum temperature difference between both panels is 5-6°C at high irradiance and panel B performance is around 0.9% lower than panel A, as Figure shows.

Therefore, the electrical behaviour of a PV panel placed on a steel roof (such as an industrial building) is affected by high temperature reached by the heat transferred from the steel plate to the panel and a lower cooling effect by natural convection if the space between both surfaces is small. So, this space is an important parameter to consider in these applications; for this reason, we have studied the temperature effect on electrical variables for three air channel thickness.

However, when the irradiance is lower at the beginning and at the end of the day, the aspect ratio does not affect the electrical outputs. For an irradiance of 970 W/m2 (at 13.30 h) the open circuit voltage increases when the aspect ratio is higher, the short circuit current decreases and the peak power increases 7.5% because the panel is cooler and its temperature is lower for high aspect ratio. So electrical production improves when the air space

underneath the PV panel increases.On the other hand, for an irradiance of 325 W/m2 these electrical variables do not vary with the aspect ratio; this in fact explains why the panel performance is similar for the three aspect ratios at the beginning and end of the day.

Having analysed the negative influence of panel temperature on electrical production due to an insufficient air space underneath it, which would allow it to be cooled by natural convection, we have analysed the panel behaviour at forced convection using a fan, for the same previous values of aspect ratio. The forced convection configuration has also been tested at three different forced velocities inside the air channel, each one for each width of the air duct . The experimental results also show that the PV panel is cooled more efficiently when the space of air underneath the panel increases, with values of the aspect ratio from 0.0525 to 0.0825.For a given value of the aspect ratio, the electrical power of a PV panel cooled by forced convection is 3–5% higher than by natural convection and it increases, as expected, when the forced velocity inside the air duct is higher. The electrical improvement is due to the decrease of PV panel temperature, being of  10–16°C. Comparing both cases of forced convection, the power increase is of 2.4% and the panel is 7°C cooler at high forced velocity.

For both natural and forced convection cases, the electrical production (power) increases 2–2.5% with a higher width of the air channel which cools the panel more efficiently, so the panel temperature is 5–7°C lower.Hence, the most significant difference has been obtained between the aspect ratio of 0.0525 and 0.0825; consequently, we have analysed the negative relationship of the temperature on the performance for these two cases, both at natural and forced convection.

The experimental results show the negative relationship between the temperature and the electrical performance of a PV panel in all the cases. While the temperature difference between the panel and ambient is not high, there is a slight difference in the performance at different configurations, but when the panel achieves high temperatures, the performance decreases sharply and we can appreciate differences in efficiency depending on the configuration and the aspect ratio. Having done this study another important thing that needs to be considered to analyze the performance of PV panels is the roof top temperature. The outer surface temperature of the roof and the outdoor dry-bulb temperature were compared assuming that the thermal conductivity of the roof thermal insulation materials was infinite; that is, that the thermal resistance of the roof is 0 m2K/W.

When the thermal conductivity of the roof thermal insulation materials was infinite, the outer surface temperature of the south-facing integrated PV array-covered gable roof was the same as the inner surface temperature but was lower than the outdoor dry-bulb temperature throughout the year. TTherefore, in the EnergyPlus models, the PV panels blocked the incident solar radiation on the roof, and the thermal radiation from the back of the PV panels was not accurately reflected.

After carefully comparing the above module the root cause of the discrepancy was found in the model from Griffith and Ellis in which the air gap between the PV panels and the building envelope was set as the “air conditioning zone.” However, in this paper, this air gap could not

be set as the “air conditioning zone” because it freely connected to the outdoor air to the cool PV panels to ensure that the panels generate power under normal conditions.

Y.M.Irwan, W.Z.Leow, M.Irwanto, Fareq.M, A.R.Amelia, N.Gomesh, I.Safwati[10].The average operating temperature of PV panel with water cooling mechanism is lower than the average operating temperature of traditional PV panel in the different fixed solar radiation. In the solar radiation of 413W/m², 620W/m², 821W/m² and 1016W/m², the decrement of the operating temperature of PV panel is 5.03°C, 7.78°C, 13.26°C and 23.17°C and by using the water cooling mechanism respectively. It can be observed that the PV panel faced higher operating temperature when the solar radiation is in excess condition. This is due that the rest of solar radiation that absorbs by PV panel converted into heat. It can be observed that the maximum voltage output of PV panels can be increased approximately by 2.15%, 8.14%, 10.89% and 14.14% for 413W/m², 620W/m², 821W/m² and 1016W/m². It can be clear that higher operating temperature is one of the impacts of environmental factors that can affect the performance of PV panel. This is because the heat that stored in PV panel will be reducing the band gap of semiconductor material, whereby affecting parameter of semiconductor materials.

Jayashree A. Gotmare, Dr. S. V. Prayagi[11].Solar PV panel with stationary cooling & without cooling were constructed in order to determine the system that will produce the higher power output. They were both placed in the sun close to each other to have the same sky condition as practicable enough. Readings were taken on both the systems simultaneously for comparison. The effect of the stationary cooling on the power generation of photovoltaic panels is investigated. The average output power for PV panels with cooling is 40.35 W and the average output power for the PV panels without cooling is 35.77W. Therefore, one can see 13% improvement in power generation for the case of using PV Panel with cooling.

Xiao Tang, Zhenhua Quan, Yaohua Zhao[12]. Results between the ordinary solar panel without the heat pipe and solar panel With heat pipe using air-cooling one day in May. The maximal air temperature, the radiation intensity, the maximal and average wind speeds are 36°C, 1001 W/m2, 5.32 m/s and 0.51 m/s, respectively. The daily net radiation is 26.3 MJ from 5:00 to 19:30.Whereas, the Results of the solar panel with heat pipe using air-cooling and water-cooling one day in May. The maximal air temperature, the radiation intensity, the maximal and average wind speeds are 35°C and 858 W/m2, 4.72 m/s and 0.51m/s, respectively.

Anna Machniewicz*, Dominika Knera, Dariusz Heim[13]. The efficiency of PV panels decreases by approximately 0.5%/K due the variation in temperature. Phase change materials are able to store specific amount of heat during changing the phase from solid to liquid and release it during reverse transition of phases. The amount of the heat that can be absorbed depends also on the density of the material and subsequently its weight ,thickness of the applied layer. Based on the most recent reports in the literature, PCM can effectively influence temperature of PV panel when it is placed in the plastic bag. In order to enhance the heat exchange and heat removal from PV panel, thermal conductivity of the material in which

PCM is closed should be maximized. Therefore, phase change temperature should be designed to lower the overheating effect during the most extreme summer months.

Cătălin George Popovici, Sebastian Valeriu Hudișteanu*, Theodor Dorin Mateescu, Nelu-Cristian Cherecheșa[14]. The value of the current produced by PV cell has an insignificant rise when the temperature of the cell is greater, but the voltage has in important reduction, causing a drop of the maximum power generated. The power of a PV cell is dependent on temperature changes and solar radiation level. Therefore, the main layers are: exterior glass, anti-reflexive coating , PV cells, ethylene-vinyl acetate , metal rear contact and polyvinyl fluoride film. The photovoltaic system is the most efficient when the temperature of the cell is about 25 °C. The angle of the ribs has an influence on the heat transfer and airflow inside the ventilated channel. A more intense heat transfer is recorded for the angle of 45°, while the case of 135° angle is considered the most disadvantageous. In consequence, the maximum temperature of the photovoltaic panel is greater for the 135°, of about 61 °C. The cooling of the photovoltaic panel is directly proportional with the height of the ribs and inversely proportional with their inclination angle.

Shaharin Anwar Sulaimana, Atul Kumar Singhb, Mior Maarof Mior Mokhtara, Mohammed A. Bou-Rabeec[15]. The effect of dust accumulation on tilted glass plates showed a reduction in plate transmittance ranging from 64% to 17%, for tilt angles ranging from 0° to 60°, respectively, after 38 days of exposure. They also observed a reduction of 30% in useful energy gain was observed by the horizontal collector after three days of dust accumulation. The dirt tends to accumulate about twice more on flat panels as compared to on tilted panel. It was discovered that dust accumulation on a glass plate tilted at 45° would reduce transmittance of solar radiation by an average of 8% after an exposure period of 10 days.The magnitude of the light radiation decreased with increase in the distance between the spotlight and the solar panel.

4.Modifications and Results:

The Energy Performance of Buildings Directive requires that RES are actively promoted in offsetting conventional fossil fuel use in buildings. A better appreciation of PV and STS integration will directly support this objective, leading to an increased uptake in the application of renewables in buildings. This uptake in RES in buildings is expected to rise dramatically in the next few years. This is further augmented by a recast of the Directive, which specifies that the buildings in EU should have nearly zero energy consumption . Meeting building thermal loads will be primarily achieved through an extensive use of renewables, following standard building energy saving measures, such as good insulation or advanced glazing systems. Both PV and STS are expected to take a leading role in providing the electrical and thermal energy needs, as they can contribute directly to the building electricity, heating, cooling and domestic hot water requirements[1].

The testing on the effect of water flow on energy performance of the heat pipe photovoltaic/thermal solar water-heating system was carried out under the testing mode C.The variation of thermal and electrical efficiencies under different water flow. It can

be seen from Fig.5 that the thermal and electrical efficiencies both decreased with the increasing water flow. As the water flow increased from 5 L/min to 9 L/min, the thermal efficiency decreased from 18.9% to 16.1%, while the electrical efficiency decreased from 12.4% to 11.3%. Every 1 L/min decrease of water flow led to a thermal efficiency decrease by 0.7% and an electrical efficiency decrease by 0.3%[2].

Effect of φ on the optical performance of HA-tracked solar panels Fig.2 presents the effects of orientation of horizontal tracking axis on the optical performance of tracked solar panels in terms of Rha-2. It is seen that, with the increase in φ , the annual solar gain on HA- tracked solar panels increased, indicating that the east-west sun-tracking (EW-axis sun-tracking) performed worst to boost the energy collection of solar panels and south-north sun-tracking (SN-axis sun- tracking performed best. It is also found that the increase of 2 −haR with the φ became slow as φ was close to 90o, showing that 10o deviation of SN-axis from the south-north direction resulted in an insignificant reduction of annual solar gain on SN-axis tracked solar panels[3].

Vijay Talekar and Vikram Shinde[4]have tabulated readings of current, voltage and power produced. The readings were taken for performance of panel at three positions. It is observed that performance of the panel with collector and with biaxial tracking is nearly 2.5times the performance of the stationary panel (45 degree in south direction) & tilted panel.

Kaushik Pal[5] obtained correlation between efficiency and wind speed. The ambient temperature has a positive correlation with the efficiency of the PV system which indicates that ambient temperature plays an important role in performance analysis.

K.A. Moharram[6] obtained that the optimum temperature is 450c, which yields the highest output energy and also expected that as the temperature value increases, the rate of water evaporation during the cooling operation will increase, and thus, more water consumption will be needed.

The solar simulator system with halogen lamp bulbs has been successfully designed and fabricated in this experiment. With a solar simulator, tests of PV panel performance can be carried out any chosen time, continued for 24 hours a day. The main objective of the solar simulator is to analysis the performance of PV panel with and without the water cooling mechanism in indoor test. The increase in operating temperature of PV panel significantly decreases the electrical yield of PV panels. DC water cooling mechanism was used to solve this problem. The experimental results mentioned that the decrement of operating temperature is around 5 - 23 ˚C increase the power output of the PV panel with a water cooling mechanism by 9 - 22 %. The increment of power output will have a significant contribution to the PV system applications. An increase in efficiency of PV panel, investment payback period of the system can reduce and the lifespan of PV panel will also be longer [10].

The maximum temperatures for the PV array without cooling & with cooling are 70 °C, and 79 °C, respectively. As it can be seen from experimental results, the maximum

module temperature equipped with stationary cooling is always higher than the conventional module temperature. However, it is obvious that the operation module temperature with stationary cooling is always below the maximum working temperature defined by the module manufacturer (90°C) so this temperature rise is supposed to be not harmful to generation characteristics. It is clear that the temperature of the PV panels increases consequently due to the increased incident solar radiation & constant mass attached at the backside of the panel. Thus, Results shows that stationary Cooling, leads to increases the PV panel output power. Therefore it is evident that the positive effect of stationary cooling is more sensible than the negative Effect due to rising panel temperature [11].

Figure: - Comparison of module temperature with and without cooling during the test day.

A novel micro heat pipe array is used for solar panel cooling. Air-cooling and water-cooling methods used are compared in this study. The results indicate that under cooling condition, the temperature can be reduced to effectively Increase the photoelectric conversion efficiency of solar panel. 1) Compared with the ordinary solar panel, the temperature of that using air-cooling reduces maximally by 4.7°C, the output power increases maximally by 8.4%, and the efficiency difference is 2.6% (In that day, the maximal air temperature and wind speed are 36°C,and 5.32 m/s ,the daily global radiation is 26.3 MJ). 2) Compared with the solar panel using air-cooling, the temperature of that using water-cooling reduces maximally by 8°C, the output power increases maximally by 13.9% and the efficiency difference is 3%. The maximum efficiency of 13.5% can be achieved the maximal air temperature and wind speed are 35°C and 4.72 m/s, the daily global radiation is 21.9 MJ) [12].

The weather parameters, different transition temperature contributes to the most noticeable reduction of PV panel’s temperature. Transition temperature should be possibly low but in the range of external temperature fluctuations. It can be observed

that the lowest transition temperature results in the smallest negative effect during the winter season while the highest temperature causes the biggest decrease in efficiency during the summer period. It confirmed that the most effective performance was obtained for the transition temperatures of 18 and 25 °C[13].

The maximum temperature of the photovoltaic panel is greater for the 135°, of about 61 °C. Lower values for operating temperature of the cell are registered for the angle of 45 °.when the height is 0.05 m, the drop of the temperature is about 2 °C [14].

Figure:-Variation of PV panel temperature (tp), efficiency (η), power (Pel) and the raise over the base case for height of ribs of 0.03 m.

The electrical power output was reduced significantly (by up to 83%) when external resistances obscured light path of the solar panel. The output power of the solar panel reduced by between 9% and 31% due to the effects of presence of talcum, between 60% and 70% due to dust, between 70% and 80% due to sand, and between 77% and 83% due to moss. When the PV panel covered with water droplets from rain or mist would result in negligible effect on output power of the solar PV[15].

5. Conclusions:

1. It was concluded that the implementation Bi-Axial system with collector effectively. The designed tracker for sun rays is found worked efficiently. The bi-axial tracking system was found effective than single axis tilting mechanism. Performance of the panel is doubled due to use of collector on the panel.

2. The extracted power was found to increase significantly by using Bi-Axial tilting Mechanism.

3. The ambient temperature had a positive correlation with the efficiency of the PV system which indicates that ambient temperature plays an important role in performance analysis. Also, there is a direct proportionality between the efficiency of the PV system and the ambient temperature of the locality.

4. The cooling rate for the solar cells was 2 LC/min which is based on the concerned operating conditions, which means that the cooling system will be operated each time for 5 min, in order to decrease the module temperature by 10 LC.

5. The result of the cooling rate model had shown good agreement with the experimental measurements and both the heating rate and the cooling rate models have been validated experimentally.

6. The PV panels yielded the highest output energy if cooling of the panels starts when the temperature of the PV panels reaches the maximum allowable temperature (MAT) 450C.

7. In the forced convection case, electrical production is higher in the modified panel than in the isolated one. This is due to the increase in the heat transferred to the air flow by forced convection.

6. References:

1. Soteris A.kalogirou, Lazaros Aresti , Paul christodoulides , Georgia florides.Faculty of Engineering and technology, Cyprus university of technology , Limassol, Cyprus.

2. Chen Hongbinga,*, Chen Xilina, Li Sizhuoa, Chu Saia aBeijing Municipal Key Lab of HVAC, Beijing University of Civil Engineering and Architecture, No.1 Zhanlanguan Road, Beijing.

3. Guihua Li 1,2, Runsheng Tang 1,*, Hao Zhong 1 1Solar Energy Research Institute Yunnan Normal University Kunming 650092, PR China 2Library of Chenggong Campus Yunnan Normal University Kunming 650500, PR China.

4. . Vijay Talekar ,Vikram Shinde, Hrushikesh Swami ,Abhishek Shete “Performance Improvement of Solar PV Panel Using Reflectors and Bi-Axial Tilting Mechanism”. IOSR Journal of Mechanical Engineering (IOSR-JMCE) e-ISSN: 2278-1684, p-ISSN: 2320-334XPP 27-31.

5. Tanima Bhattacharya, Ajoy K. Chakraborty, and Kaushik Pal “ Effects of Ambient Temperature and Wind Speed on Performance of Monocrystalline Solar Photovoltaic Module”. Hindawi Publishing Corporation Journal of Solar Energy Volume 2014, Article ID 817078.

6. K.A. Moharram , M.S. Abd-Elhady , H.A. Kandil , H. El-Sherif “Enhancing the performance of photovoltaic panels by water cooling” Ain Shams Engineering Journal (2013) 4, 869–877 Received 29 September 2012; revised 8 February 2013; accepted 24 March 2013.

7. International Journal of Photoenergy , Volume 2013 (2013), Article ID 830968”Improving the Electrical Parameters of a Photovoltaic Panel by Means of an Induced or Forced Air Stream” R. Mazón-Hernández, J. R. García-Cascales, F. Vera-García, A. S. Káiser, and B. Zamora

8. Journal of Solar Energy ,Volume 2014 (2014), Article ID 132950 ”Optimum Tilt Angle for Photovoltaic Solar Panels”B. Kamanga, J. S. P. Mlatho, C. Mikeka, and C. Kamunda

9. International Journal of Photoenergy Volume 2016 (2016), Article ID 9020567”The Effect of Photovoltaic Panels on the Rooftop Temperature in the EnergyPlus Simulation Environment” Changhai Peng and Jianqiang Yang.

10. Y.M.Irwan, W.Z.Leow, M.Irwanto, Fareq.M, A.R.Amelia, N.Gomesh, I.Safwati. Indoor Test Performance of PV Panel through Water Cooling Method, Centre of Excellence for Renewable Energy, School of Electrical System Engineering, University Malaysia Perlis (UniMAP), Malaysia. Institute of Engineering Mathematics, University Malaysia Perlis, (UniMAP), Malaysia. Energy Procedia 79 (2015) 604 – 611.

11. Jayashree A. Gotmare, Dr. S. V. Prayagi, Enhancing the Performance of Photovoltaic Panels by Stationary, Mechanical Engineering Department, Dr. Babasaheb Ambedkar College of Engineering & Research, Maharashtra, India. International Journal of Science, Engineering and Technology ISSN: 2348-4098.

12. Xiao Tang, Zhenhua Quan, Yaohua Zhao Experimental Investigation of Solar Panel Cooling by a Novel Micro Heat Pipe Array, Architectural and Civil Engineering Institute, Beijing University of Technology, Beijing, China. Energy and Power Engineering, 2010, 2, 171-174.

13. Anna Machniewicz*, Dominika Knera, Dariusz Heim Department of Environmental Engineering, Lodz University of Technology, ul. Wólczańska 213, 90-924 Łódź, Poland.

14. Cătălin George Popovici, Sebastian Valeriu Hudișteanu*, Theodor Dorin Mateescu, Nelu-Cristian Cherecheșa aFaculty of Civil Engineering and Building Services, “Gheorghe Asachi” Technical University of Iasi, 13 Dimitrie Mangeron, Iasi, 700050, Romania.

15. Shaharin Anwar Sulaimana, Atul Kumar Singhb, Mior Maarof Mior Mokhtara, Mohammed A. Bou-Rabeec,* aDepartment of Mechanical Engineering, Universiti Teknologi Petronas, 31750 Tronoh, Perak, Malaysia bDepartment of Engineering Design, Indian Institute of Technology, Madras, India cPublic Authority for Applied Education &Training, Department of Electrical Engineering, College of Technological Studies, Kuwait.