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energy into electricity by the photovoltaic effect. A solar cell constitutes the basic unit of a PV generator which, in turn, is the main component of a solar generator.
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International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459 (Online), Volume 4, Special Issue 1, February 2014) International Conference on Advanced Developments in Engineering and Technology (ICADET-14), INDIA.

Influence of High Module Temperature on Output of Opaque and Semitransparent Type Photovoltaic Modules: A Comparative Analysis Saurabh Kumar Rajput1, Rakesh Sharma2, R.C. Yadaw2, Vimal Chaturvedi2 1,2

NITRA Technical Campus, Ghaziabad

Email: [email protected] Abstract- This paper investigates the influence of thermal heating on opaque and semitransparent photovoltaic (PV) module’s parameters e.g. open circuit voltage, short circuit current, load voltage, load current, power and efficiency. A comparative study is also done between the opaque and semitransparent PV modules for considering the effect of thermal heating on power output of these two modules. Index TermsOpaque photovoltaic module, semitransparent photovoltaic module, Module Temperature, Intensity

I. INTRODUCTION Energy supply plays very important role for every country in the world. Energy is practically needed for all the activities of human being and it is required to improve our quality of life. In the recent years , considerable efforts are made worldwide to improve the energy situation as well as various renewable energy based mini grid solutions in the rural areas of developing country so as to meet the increasing requirements for basic need and other development activities. It was due to higher prices and limited energy resources of conventional or fossil fuels. The new options should be eco-friendly as well as abundant in nature .The various options may be wind energy, biomass, fuel cells and solar energy etc. Among all the available options, solar energy is eco friendly, freely available and pollution free. Thus, the solar energy based systems can meet energy demands to some extent and keep the environment pollution free, A. Tiwari et al. [1] A solar cell or PV cell is a device that converts solar energy into electricity by the photovoltaic effect. A solar cell constitutes the basic unit of a PV generator which, in turn, is the main component of a solar generator. A PV generator is the total system consisting of all PV modules which are connected in series or parallel or combination of both series and parallel with each other.

Photovoltaic module is a packaged interconnected assembly of photovoltaic cells made up of crystalline silicon [2-3]. G. N.Tiwari et al. [4] evaluated that the Crystalline silicon has an ordered crystal structure, with each atom ideally lying in a predetermined position. Mono-crystalline PV modules exhibit predictable and uniform behavior, are highly efficient but are the most expensive type of silicon. Recently the majority of solar cells are made from pure mono-crystalline silicon produced for the Semiconductor industry, having no impurities or defects in its lattice. K. E. Park et al. [2] evaluated that the production of multi-crystalline silicon is simpler and cheaper than those required for mono-crystalline material. However, the material quality of multi-crystalline is lower than that of mono-crystalline material due to the presence of grain boundaries. There are two types of crystalline PV modules namely opaque PV modules and semitransparent PV modules [5-10]. Opaque PV Module: In opaque PV module, glass cover is used on front side of solar cell and insulating material, white in color is used on back side of solar cells. In it unused solar energy in solar cell is responsible to raise the cell temperature and the energy received by the space between two solar cells is also responsible for increasing the temperature. The bottom heat loss is less in opaque module in comparison to the semitransparent module because insulating material (white tedlar) at its back surface. G. N. Tiwari et al. [4] Energy Balance Equation for Opaque PV Module: [ (

( ) ( )]

)

( )]

[

( )

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(

) ( )

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International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459 (Online), Volume 4, Special Issue 1, February 2014) International Conference on Advanced Developments in Engineering and Technology (ICADET-14), INDIA. Semitransparent PV Module: In semi transparent PV module glass is used on both front and back side of PV module. In it whatever solar energy falls on non packing area goes directly out which is called as direct gain. In it only unused solar energy is responsible to raise the cell temperature. The bottom heat loss is more in semitransparent module in comparison to the opaque module K.E. Park et al. [2]. Energy Balance Equation for Semitransparent PV Module: [

( ) ( ( )

)

(

)] ( )

II. EXPERIMENTAL EQUIPMENTS Solar Simulator: The solar simulator is shown in Fig. (1). PV Module is tested under solar simulator which has 16 tungsten halogen lamps. Each lamp is 500W and rated at 240 V and 11A. The halogen lamps are arranged in 4 4 metrics for uniform distribution of intensity. As the number of the halogen lamps is large and the diffuse angle of the light is high, the intensity falling on the photovoltaic module is uniform.

Solarimeter: Solarimeter is used to measure the intensity of radiation falling on PV modules. It has a least count of 20 W/m2. It is manufactured by CEL India Ltd. Solarimeter has been calibrated with standard Pyranometer. Voltmeter and Ammeter: A digital multi-meter is used for measurement of voltage and current under variable load conditions. Infrared thermometer: The infrared thermometer is used to measure top surface temperature of opaque type PV module. PV Module for Testing: A opaque type PV module (module no. S 020854) and a semitransparent type PV module (module no. S 6224) are used for testing. The module area is 0.61 m2 and peak power is 75 Watts. III. P ARAMETERS T O B E MEASURED The following parameters are to be measured during the Experimentation 1. Module temperature (ºC). 2. Intensity (W/m2). 3. Load current, IL (Amp.) and load voltage, VL (Volt). Parameters to be calculated The following parameters are to be calculated after the Experimentation 1. DC Power output by the modules. 2. Efficiency of PV Modules. IV. OBSERVATIONS The semitransparent and opaque PV modules are tested under solar simulator for same intensity. The temperature of modules is measured by infrared thermometer and voltages, current are measured by multi-meter. A rheostat is used here, to measure the voltage and current of modules at variable load condition. The observations are shown in table 1 and 2.

Fig. 1 Solar Simulator at CES, IIT Delhi

 For semitransparent PV module Average Intensity, Ī (t) = 600 W/m2. Module Temperature, T = 55 ºC

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International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459 (Online), Volume 4, Special Issue 1, February 2014) International Conference on Advanced Developments in Engineering and Technology (ICADET-14), INDIA. 3

50

Table-2 Variation of V, I and Power with Load for Module S020854 at 600 W/m2

45

Current (Amp.)

2

40

V (Volt)

I (Amp.)

P (Watt)

35

0.0

1.8

0.0

8.8

1.6

14.08

9.2

1.5

13.80

10.0

1.4

14.00

10

16.9

1.0

16.90

5

17.6

0.7

12.32

17.8

0.5

8.90

17.9

0.4

7.16

19.4

0.0

0.0

30

1.5

25 20

1

Power (Watt)

2.5

15

0.5 0

0 0

10(Volt) Voltage

I (…

20

Fig. 2 Variation of Current and Power with Voltage of Module (S 6224) at 600 W/m2 Table-1 Variation of Voltage, Current and Power with Load for Module S 6224 at 600 W/m2



1.8

45

1.6

40

1.4

35

1.2

30

1

25

0.8

20

0.6

15

22.40

0.4

10

0.9

15.48

0.2

5

17.3

0.7

12.11

0

0

17.6

0.2

3.52

Fig. 3 Variation of Current and Power with Voltage of Module (S 020854) at 600 W/m2

19.7

0.0

0.0

The semitransparent PV Module (S 6224) is tested under solar simulator at CES, IIT Delhi with average intensity 600 W/m2. At this average intensity, the module is first tested for short circuit condition. During short circuit, the voltage measured is zero and the current measured is 2.4 Amp.

P (Watt)

0.0

2.4

0.0

0.2

2.3

0.46

8.4

1.7

14.28

13.3

1.8

23.40

13.4

1.7

22.78

16.0

1.4

17.2

For opaque PV module

Average Intensity, Ī (t) = 600 W/m2. Module Temperature, T = 67 ºC

0

5

Voltage 10 (Volt) 15

20

Lord Krishna College of Engineering (An ISO 9001:2008 Certified Institute) Ghaziabad, Uttar Pradesh, INDIA.

Power (Watt)

50

I (Amp.)

Current (Amp.)

2

V (Volt)

25

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International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459 (Online), Volume 4, Special Issue 1, February 2014) International Conference on Advanced Developments in Engineering and Technology (ICADET-14), INDIA. Afterwards voltage and current of module are measured at open circuit condition. For open circuit condition, current measured is zero and voltage measured is 19.7 volt. After testing the module under open circuit and short circuit conditions, the output current and voltage of module are obtained for variable load condition and it is measured by multi-meter. The DC power obtained from the module is calculated by multiplying the output voltage and the output current, as shown in the Table 1. The power output is zero at both the open circuit and short circuit conditions but it has a significant value under variable load conditions. For the varying load, the power first increases until it reaches a peak value. After the peak, it starts decreasing and finally becomes zero. These results are shown in Fig 2. Now the opaque PV module (S 020854) is tested under solar simulator for the same average intensity of 600 W/m2. Its results are shown in Table-2 and Fig. 3. V. RESULTS AND D ISCUSSIONS The semitransparent photovoltaic module and opaque PV module, both are tested for the same average intensity of 600 W/m2. The peak output power of semitransparent PV Module is 22.78 Watt and that for the opaque PV module 16.90 Watt. The output power of opaque PV module is less than semitransparent PV module because in opaque PV module, the glass cover is used on front side of module and insulating material (white tedlar) is used on back side of module. In opaque PV module, the unused solar energy in solar cells of module is responsible to raise the solar cell temperature and the energy received by the space between two solar cells (non packing area) is also responsible for increasing the cell temperature. In semi transparent PV module, the glass cover is used on both front and back side of module. In it whatever solar energy falls on non packing area goes directly out which is called as direct gain. So in such modules, only unused solar energy is responsible to raise the cell temperature. The bottom heat loss is less in opaque module in comparison to the semitransparent module because of insulating material (white tedlar) at its back surface and this is responsible for increasing the cell temperature of opaque PV modules. When the cell temperature increases, the saturation current also increases with intrinsic carrier concentration so the open circuit voltage of module reduces and the short circuit current of module increases.

But the effect of increasing module temperature on short circuit current is small than open circuit voltage so the overall effect of increased module temperature is a reduction in output power of module hence the efficiency of module reduces. Acknowledgement We thank to Prof. G. N. Tiwari, Centre for Energy Studies, Indian Institute of Technology (IIT) Delhi, for his active cooperation at various stages of the work. REFERENCES [1]

[2]

[3]

[4]

[5]

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[8] [9]

[10]

N. Tiwari, P. Barnwal, G.S. Sandhum and M.S. Sodh, “Energy Metrics Analysis of HybridPhotovoltaic (PV) Modules,” Applied Energy, Vol. 86, pp. 2615–2625, 2006. K. E. Park, G. H. Kang, H. I. Kim, G. J. Yu and J.T. Kim, “Analysis of Thermal and Electrical Performance of Semi-transparent Photovoltaic (PV) Module,” Energy Journal, Vol. 35, pp. 2681– 2687, 2010. S. Nayak “Energy Metrics of Photovoltaic/thermal and Earth Air Heat Exchanger Integrated Greenhouse for Different Climatic Conditions of India,” Applied Energy Journal, Vol. 87, pp. 29842993, 2010. G. N. Tiwari, R. K. Mishra and S. C. Solanki, “Photovoltaic Modules and Their Applications: A Review on Thermal Modeling,” Applied Energy Jornal, Vol. 88, pp. 2287–2304, 2011. S. C. Solanki, S. Dubey and A. Tiwari, “Indoor Simulation and Testing of Photovoltaic Thermal (PV/T) Air Collectors,” Applied Energy Journal, Vol. 86, pp. 2421–2428, 2009. J. K. Kaldellis, D. Zafirakis and E. Kondili, “Energy Pay-back Period Analysis of Stand-alone Photovoltaic Systems,” International Journal of Renewable Energy, Vol. 35, pp. 1444–145, 2010. Dyk, B. Scott, E. L. Meyer, A. Leitch, “Temperature Dependence of Performance of Crystalline Silicon Modules,” South African Journal of Science, Vol. 96, pp. 198-200, 2000. J. A. Mazer, “Solar Cells: an Introduction to Crystalline Photovoltaic Technology,” Kluwer Academic Publications, Vol. 108, 1997. E. L. Meyer, V. Dyk, “Degradation analysis of silicon photovoltaic modules,” Proceedings of 16th European PV Solar Energy Conference, p. 2272-2275, 2000. K. Kato, A. Murata, K. Sakuta, “Energy Payback Time and Lifecycle CO2 Emission of Residential PV Power System with Silicon PV Module,” Prog. Photovolt Res. Applied Journal, Vol. 6, Vol. 105–115, 1998.

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