Analysis of Efficiency of Solar PV Cell

Analysis of Efficiency of Solar PV CellThe efficiency estimation is the most frequently order used to compare the work of solar cellphones. This method merchantman be defined as the ratio of power output from the solar cell over the irradiance power output. In addition of estimating the performance of the solar cell itself, the efficiency depends on the spectrum, intensity of sunlight and the temperature of the solar cell (Fouladi et al., 2013). The efficiency of solar cells can be estimated using the by-line Equation 3.15Where I is the output current, V is the voltage, A is the aperture surface area of the PV faculty. P is the electrical power generated, GT is the solar radiation flux on module plane (W/m2) and is the cell/module electrical efficiency. The panel efficiency is momented by the cell temperature and irradiance and this effect in efficiency can by estimated by connecting the existing environment conditions to a reference condition using the following Equation 3. 16 (Fouladi et al., 2013)ref is the cell efficiency at the reference temperature, Tref (typically 25 C), 1000 W/m2 is the reference solar irradiance. is the temperature coefficient and is the solar irradiance coefficient and both coefficients depend on the PV materials.From Equation 3.16, it can be noticed that an increase in cell temperature (TC) would result in decrease in efficiency (Fouladi et al., 2013). The value of is often assumed to be zero and Equation 3.17 will beref and act upon are given by the manufacturers. However, the can be estimated using a flash test in which the cells electrical output is metric at two different temperatures for given solar radiation flux (Hart and Raghuraman, 1982 Skoplaki and Palyvos, 2009). The actual value of it depends on Tref along with the dependence on PV materials and it can be given by Equation 3.18T0 is the temperature at which the electrical efficiency of the PV module reach is zero (Garg and Agarwal, 1995 Skoplaki and Palyvo s, 2009). For crystalline silicon solar cells the highest temperature in at which the PV module electricity drops to Zero is 270 C (Evans and Florschuetz, 1978 Skoplaki and Palyvos, 2009).The output voltage decreases significantly with the increase of the cell temperature and that causes the current to increase slightly. Nominal operation cell temperature method (NOCT) is used to estimate the cell temperature. This method estimates the cell temperature by measure the cell temperature of an open-rack PV module under an open circuit and in a streamer reference environment Fouladi et al., 2013).The solar radiation is estimated typically to be 800W/m2 (GT, NOCT) and the PV panel is tilted 45 from the horizontal and exposed to 20 C air (Ta, NOCT) at 1 m/s. Equation 3.19 can be expressed as (Fouladi et al., 2013)Tc = Where UL is the thermal prejudice coefficient, Ta is the air temperature and GT is the irradiance on the plane of the panel. Coefficient is the solar transmittance of glaz ing and coefficient is the solar absorptance of the PV layer. is the electrical efficiency. According to (Duffie and Beckham, 1980 Fouladi et al., 2013), the term is negligible so Equation 3.20 will becomeTc = UL which is the overall heat loss for the panel can be estimated using the following Equation 3.20UL = Where h is the convective heat loss coefficient and qrad is the radiation heat loss from the panel.There are other environmental factors that can influence the performance and the efficiency of the PV cells other than the temperature such as (Mekhilef et al., 2012)DustDust accumulation on the surface of PV panel reduces the meter of irradiance required for PV cell to reach maximum efficiency. The excessive accumulation of dust decreases the quality of the solar cells.HumidityThe effect of the humidity it is somehow comparable to the effect of the dust. The water vapor particles decreases the level of the sunlight irradiance needed for the PV panel to reach the maximum ef ficiency. When the PV surface becomes moist, the light is scattered either by reflection, diffraction or bending when it comes in contact with the water droplets.Beside the environmental factors that affect the efficiency of the PV panel, there are technical factors that are based on electricity generation carcass that also can influence the efficiency of the module such as (Darwish et al., 2013)Effect of tilt angleThe tilt angle is one of major factors that determine the performance of the PV panels. The variation of the angle that the system is set with can control the level of the dust disposition on the grouch and the amount of irradiance transmission of the house under various weather conditions.Effect of PV TechnologyPhotovoltaic technology is classified into two separates which are silicon crystalline and thin film. Each group of PV modules consists of different types of solar cells. These different types of solar cell vary also in their efficiencies, resistance to high temperatures and also resistance to harsh environment locations. The investigations prove that a-Si performs best in dusty environment.Effect of CleaningThere are four methods to remove the dust and reduce the effect of the dust on the PV glass panel such as (1) Natural, (2) Mechanical, (3) electro-mechanical and (4) electrostatic. The natural cleaning method is considered to be the simplest removal method because it depends on the rainfall and wind clearing.ReferencesFouladi, F. Henshaw, P. and Ting, S. D. K. (2013) Enhancing Smart Grid realization with accurate prediction of photovoltaic performance based on weather forecast, International Journal of Environmental Studies, vol. (70), no. (5), pp. 754-764, DOI 10.1080/00207233.2013.798497Skoplaki, E. and Palyvos, J. A. 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