Paper id 26201469

International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637

Performance Analysis of Photovoltaic Panel Array on the Basis of Temperature Variation Kavitha H. N1, Rajiv Dahiya2, Electronics and communication1, 2, PDM college of Engg1, 2 Email: kavithahn.ec@gmail.com1, rajiv_engg@pdm.ac.in2 Abstract- This paper is concerned with “Performance Measure of Direct Coupled Architecture Design of Photovoltaic Panel Array�. The performance of Photovoltaic Panels measured on the basis of the efficiency of the system by variation in the temperature and by variation in solar radiation. There are two main parameter that used to analysis the performance of the PV array with variation in temperature and constant radiation.

Extensive simulation results are presented to verify these two performances. In this thesis we are analysis the performance of the PV array by using both the simulation results and simulink model. PV array gives higher efficiency. We analysis the PV array on the basis of I-V, P-V and P-I characteristics by varying any one of the parameter either temperature or solar radiation and taking other parameter constant.

Index Terms- PV, Photovoltaic, Temperature, Radiation 1. INTRODUCTION Energy is an essential ingredient for socio-economic development and economic growth. Global warming, exhaustion and high cost of fossil fuels dictates the exploitation of alternative sources of energy such as wind and solar energies. Renewable sources of energy acquire growing importance due to its enormous consumption and exhaustion of fossil fuel. Renewable energy is abundant, free, sustainable, and clean and can be harnessed from different sources in the form of wind, solar, tidal, hydro, and geothermal and biomass.

Energy supplied by the sun in one hour is equal to the amount of energy required by the human in one year.

Visible light undergoes effective solar energy conversion by the typical dye sensitized solar cells, but is detrimental to silicon solar cells [4-9]. In contrast, near-infrared light is not utilized by these dye cells, but results in high efficiencies for silicon.

Photo voltaic are solar cells that convert sunlight to D.C. electricity. The solar cells in a PV module are made from semiconductor materials. a switching system that changes the cell array topology and connections or the structural connections of the arrays to establish the required voltage during different periods of a day [10].

A PV array is made up of rectangular modules (or panels) that measure between 2 and 5 feet on a side.

The most common type of PV module has an aluminum frame and a glass cover protecting a collection polycrystalline PV cells. When exposed to light, each PV cell produces 0.5 volt DC — so if you add up the number of cells and divide by 2, you know the voltage of the module. The best performing commercially available PV cells are roughly 20% efficient at converting solar energy into electricity. PV panels are usually connected in series, parallel, or a combination of series and parallel to achieve the desired power level [7]. Modular maximum power point tracking (MPPT) algorithms have resulted in a net overall efficiency gain of up to 25% [8].

Unlike polycrystalline PV cells, thin-film (amorphous) PV products are manufactured on a flexible sheet. These thin-film PV products have many applications; for example, they are used to make PV roof shingles and peel-and-stick membranes designed for use on metal roofing. Thin-film PV products have relatively low efficiencies usually in the range of 10% to 12% so they require almost twice the area required for a polycrystalline PV array with the same electrical output.

Fig. 1Equivalent circuit of photovoltaic cell

The operation of a photovoltaic (PV) cell requires 3 basic attributes:

The absorption of light, generating either electron-hole pairs.

The separation of charge carriers of opposite types.

The separate extraction of those carriers to an external circuit.

This electricity can then be used to power a load, such as a water pump, or it can be stored in a battery.

PV cells are based on a variety of light-absorbing materials, including crystalline and amorphous silicon, thin films such as cadmium telluride (CdTe) and copper indium gallium selenide (CIGS) materials, and organic/polymer-based materials.

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International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637 A PV cell may be represented by the equivalent circuit model shown as fig. 1, consisting of a photon current source (IL), a diode, a series resistance (rs), and a shunt resistance (rsh).The series resistance (rs) represents the ohmic losses in the front surface of the cell and the shunt resistance (rsh) represents the loss due to diode leakage currents.

The conversion efficiency ( ) is defined as:

…(1)

and the fill factor (FF) given by

...(2) where Pin is the power input to the cell, Voc is the open circuit voltage, Isc is the short circuit current, and Im and Vm are the maximum cell current and voltage respectively at the maximum power point,

Pm = ImVm. Critical PV cell performance parameters, such as the equivalent cell shunt and series resistance and the electrical conversion efficiency and fill factor, may be determined from I-V measurements. The cell must be maintained at a constant temperature and a radiant source with a constant intensity and a known spectral distribution must be used.

2. PHOTOVOLTAIC CELL PERFORMANCE FACTOR Several factors exist that affect the performance of solar cells. The light source’s spectral intensity affects the performance of a solar cell for good or bad, since the output power of a solar cell is dependent on the power made available to it 2.1 Negative Factors affect the performance of Photovoltaic Cell Several factors exist that negatively affect the performance of solar cells. Some of these negative factors [1] are listed here: The natural reflection of light off the surface of solar cells can greatly reduce efficiency.

The reflection of light can be as high as 36% for untreated surfaces.

The reflection of light off the surface due to the electric conductors further decreases the efficiency by reducing the amount of light shining through the solar cell. The reduction in light is equivalent to how much these contacts cover the surface, which is typically 8%.

Photons entering the solar cell with a lower or higher energy level than the band gap

energy level of the material can lower efficiency by creating heat and raising the temperature of the solar cell.

The material’s natural recombination rate of electron-hole pairs through direct and indirect recombination can reduce current flow and lower the efficiency of solar cells.

However, the recombination rate is often greater due to material defects from impurities and imperfect crystal structures.

Resistance present in the solar cell reducing charge and current flow reduces solar cell efficiency. This resistance exists in the bulk of the base, at the surface, and at the contact junction. Additionally, ohmic resistance in the metal contacts adds to the reduction of efficiency.

Operating the solar cell at a higher or lower temperature than what is optimal for its particular design also reduces efficiency since the lattice vibrations that result reduce the flow of carriers. The author discusses the effect of temperature in more detail later.

Over time, the performances of solar cells in space applications are degraded.

2.2 Positive Factors affect the performance of Photovoltaic Cell On the other hand, positive factors also exist to improve the performance of solar cells [1]. Some of these factors are as follows: Making solar cells with shallow junctions that are less than 0.2 microns thick are called blue cells and can improve the efficiency of solar cells.

Making the solar cell with a back surface field (BSF), which is a p+ layer on the bottom of the cell, can increase VOC and ISC resulting in a better FF and a higher efficient cell.

The reflection of light off the surface of the solar cell can be reduced from as high as 36% to 5% if an antireflection coating, such as Silicon Oxide (SiO), and surface texturing are used.

Surface texturing alone can increase solar cell efficiency by approximately 8%.

The addition of a back surface reflector acting as a mirror to reflect the light back through the cell can increase efficiency by 3%.

Producing multilayer solar cells can increase efficiency.

3. PHOTOVOLTAIC MODULE SYSTEM 3.1 Photovoltaic cell PV cells have been made with silicon (Si), gallium arsenide (GaAs), copper indium diselenide (CIS),

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International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637 cadmium telluride (CdTe), and a few other materials.

The common denominator of PV cells is that a p–n junction, or the equivalent, such as a Schottky junction, is needed to enable the photovoltaic effect [2]. Understanding the p–n junction is thus at the heart of understanding how a PV cell converts sunlight into electricity.

The equivalent circuit for a solar cell is shown in fig.

2. To determine the current-voltage characteristics of a solar cell it is first necessary to introduce two parameters important in photovoltics: short-circuit current ISC and open-circuit voltage VOC [5]. Shortcircuit current is the current delivered when the leads are shorted together. In this situation the voltage across the diode is zero, and thus no current flows through the diode but all the current flows through the shorted leads. Ideally, the short-circuit current is equal to the light-generated current. The open-circuit voltage in turn is the voltage when the leads are not connected, and in this situation the current is clearly zero.

output of a module is a sum of the voltages of its cells connected in series. To increase the current, cells are connected in parallel, and similarly the current output of a module is a sum of the currents of the individual cells connected in parallel. In the I − V curve of a module with a number of cells connected in series and parallel the curves of individual cells simply add up along the voltage and current axes, respectively. To increase the output even more for a larger-scale electricity production system, several modules are connected in series and parallel to form a PV array.

Fig. 3 Photovoltaic Array

The power produced by a single module is seldom enough for commercial use, so modules are connected to form array to supply the load [6]. The connection of the modules in an array is same as that of cells in a module. Modules can also be connected in series to get an increased voltage or in parallel to get an increased current.

Fig. 2 Equivalent circuit for a solar cell

The actual current in a solar cell is the ideal current, i.e. the short-circuit current ISC, minus the current that flows through the diode, Id …(3) To get the relation of current and voltage in a PV cell we substitute the Shockley diode equation to the equation above. This yield

… (4) 3.2 Photovoltaic module/array A photovoltaic array [2-3] (PV system) is an interconnection of modules which in turn is made up of many PV cells in series or parallel. As the voltage output of one PV cell is only about 0.5 V, several cells are coupled in series in order to increase the output. An assembly of a number of cells coupled and encapsulated in an appropriate package is called a solar or PV module that is the basic element for photovoltaic electricity production. The voltage

4. SIMULATION RESULTS Performance analysis based on the Temperature variation and constant radiation There are three classic parameters that are very important on the PV characteristics namely shortcircuit current (Isc), open-circuit voltage (Voc) and the maximum power point (Pmp = Imp*Vmp). Experiment is performed for radiation (s=100) and temperatures as 15oC, 20oC, 25oC, 30oC, 35oC, 40oC, 45oC. The power delivered by a PV cell attains a maximum value at the points (Imp; Vmp). Fig. 4 shows the I-V curve at 15oC temperature and constant irradiance. Fig.5 Demonstrate the P-V curve at 15oC temperature and constant irradiance. Fig. 6 depicts the P-I curve at 15oC temperature and constant irradiance. Fig. 7 shows the I-V curve at various temperature and constant irradiance. Fig. 8 demonstrate the P-V curve at various temperature and constant irradiance

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International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637

Fig. 4 I-V curve at 15oC temperature and constant irradiance Fig. 7 I-V curve at various temperature and constant irradiance

Fig. 5 P-V curve at 15oC temperature and constant irradiance

Fig. 8 P-V curve at various temperature and constant irradiance

5. CONCLUSION

Fig. 6 P-I curve at 15oC temperature and constant irradiance

This paper is concerned with Photovoltaic Panels with Improved Efficiency. Here, the performance of Photovoltaic Panels on the basis of the efficiency of the system by variation in the temperature and by variation in solar radiation. The main parameter that is used to analysis the performance of the PV array is analysis with variation in temperature and constant radiation. The performance of PV array is measured using both the simulation results and simulink model.

Analysis of PV array on the basis of I-V, P-V and P-I characteristics by varying any one of the parameter either temperature or solar radiation and taking other parameter constant.

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International Journal of Research in Advent Technology, Vol.2, No.6, June 2014 E-ISSN: 2321-9637 REFERENCES [1] “Space Power and Radiation Effects,” class notes for EC3230, Department of Electrical and Computer Engineering, Naval Postgraduate School, Spring 2009.

[2] Frank kreith, D. Yogi Goswami, 2007, Handbook of Energy Efficiency and Renewable Energy, CRC Press, 2007.

[3] Markvart, T. and Castaner, L., (2003), "Practical Handbook of Photovoltaics, Fundamentals and Applications" Elsevier, 2003.

[4] Singh, A. ; Hota, A.R. ; Patra, A. “Design and implementation of a programmable solar photovoltaic simulator”, International Conference on Power, Control and Embedded System , Pag: 1 – 5, 2010.

[5] Trabelsi,M. ; Ben-Brahim, L., "Development of a grid connected photovoltaic power conditioning system based on flying capacitors inverter”,International Multi-Conference on Systems, Signals and Devices (SSD), Pag: 1 – 6, 2011.

[6] Zia, F.B. ; Salim, K.M. ; Yousuf, N.B. ; Haider, R. ;Alam, M.R., “Design and implementation of a single phase grid tie photo voltaic inverter” International Conference on the Developments in Renewable Energy Technology (ICDRET), Pag: 1 – 4, 2012.

[7] Bishal Dhakal and Fernando Mancilla–David, “Centralized and Modular Architectures for Photovoltaic Panels with Improved Efficiency,” IEEE, 2012.

[8] A photovoltaic systems using advanced mppt method implemented in matlab. [Online].

Available: http://www.eetimes.com.

[9] I. H. Altas and A.M. Sharaf.”A Photovoltaic Array Simulation Model for Matlab-Simulink GUI Environment,” IEEE, 2007.

[10] Z. M. Salameh and F. Dagher: The effect of electrical array reconfiguration on the performance of a PV powered volumetric water pump, IEEE Trans., EC-5, pp. 653 658, 1990.

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