- Email: [email protected]
The Effect of Water Vapor on the Performance of Solar Cells
Physics Procedia 21 (2011) 108 – 114
The seventh International Conference on Material Sciences (CSM7)
The Effect of Water Vapor on the Performance of Solar Cells A. Guechia,*, M. Chegaarb, A. Merabeta a
Institute of Optics and Precision Mechanics, Ferhat Abbas University, 19000, Setif, Algeria b Department of Physics, Ferhat Abbas University, 19000, Setif, Algeria [email protected]
Abstract The objective of this study is to determine the effect of variations in global spectral distribution due to the variation of water vapor on the performance of two types of solar cells, nanocrystalline silicon (nc-Si:H) and cadmium telluride (CdTe) using the spectral irradiance model for clear skies SMARTS2 over a typical rural environment in Setif. Water vapor can reduce the amount of sunlight reaching a solar cell, and thereby cause a reduction in the electrical current, fill factor, open circuit voltage. The results indicate that water vapor increase in the atmosphere reduces the short circuit current of the CdTe cell by 3.15% while this reduction is about 2.38% for the (nc-Si:H) cell. The efficiency for both cells increases with increasing water vapor. These findings should be taken into consideration by solar cell engineers for better sizing of these types of solar cells. © 2011 Published by Elsevier B.V. Open access under CC BY-NC-ND license.
Selection and/or peer-review under responsibility of the Organizer. Keywords: CdTe, (nc-Si:H), Solar Cells, Efficiency, Water Vapour, Global Irradiance, Spectral Variation, SMARTS model.
*
Corresponding author: Email: [email protected]
1875-3892 © 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of the Organizer. Open access under CC BY-NC-ND license. doi:10.1016/j.phpro.2011.10.016
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
109
1. Introduction In recent years new thin film technologies have entered the photovoltaic (PV) marketplace and are now available commercially, namely cadmium telluride (CdTe), Copper-Indium-Gallium-Diselenide (CIGS), and hydrogenated amorphous silicon (a-Si-H). These technologies exhibit a steadily improving efficiency and are potentially cheap to produce. Today CdTe is one of the leading thin film photovoltaic materials due to the optimum band gap of 1.5 eV for the efficient photo conversion and high optical absorption coefficient (tKLFNQHVVRIDSSUR[LPDWHO\ȝPZLOODEVRUEQHDUO\RIWKe incident solar radiation) [1]. The amorphous silicon/nanocrystalline silicon (a-Si/nc-Si) tandem solar cell is a promising candidate for use as the next-generation of thin film solar cells. Compared to other thin-film technologies currently under development and being presently industrialized (CIGS, CdTe), silicon thin-films have the key advantage of using silicon as raw material that is non-WR[LF DQG ZLGHO\ DYDLODEOH LQ WKH HDUWK¶V FUXVW $OWKRXgh this material has a complex nanostructure, its optical properties have a marked crystalline characteristic. The band gap of the nanocrystalline areas should be around 1.1 eV; while for the amorphous, it is around 1.7-1.8 eV [2]. With these band gaps, the ncSi: H diode should have a much higher forward current density than the CdTe. This implies the spectral absorption of nanocrystalline silicon covers a much larger range. Nanocrystalline silicon absorbs light coming from a wider spectral range, extending to 1100 nm [2]. Furthermore, the nc-Si: H solar cell is reported to be largely stable against light induced degradation [3]. Another advantage of the (nc-Si: H) and CdTe technologies is the flexibility with regards to the method of manufacture. Global solar radiation at surface level is an important parameter in designing systems employing solar energy, such as high temperature heat engines, high intensity solar photovoltaic cell, building designing, horticulture, etc. Manufacturers report photovoltaic module power output at standard testing conditions (STC), which correspond to 1000 W/m2, 25°C, air mass 1.5 and normal incidence. In real operating conditions however, the module output is strongly affected by various environmental conditions such as irradiance, temperature, spectral effects. Furthermore the impact of each climatic factor on the energy production varies according to the module technology in use [4]. The performance of solar cells is influenced by the solar radiation at ground level that is not only place and time dependent but also varies in intensity and spectrum due to varying atmospheric parameters as turbidity, water vapor, air mass, and albedo. The effect of the variations of the solar spectrum on the performance of the different photovoltaic devices is not yet quantified on a large scale and few works have been published [5]. This is mainly due to the difficulty to obtain spectral measurements especially for developing countries for not being able to afford the necessary equipment. The aim of this study is to evaluate the effect of changes in spectral distribution of global irradiation due to the variation of atmospheric parameters such as water vapor content on the performance of two types of solar cells, nanocrystalline silicon (nc-Si-H) and cadmium telluride (CdTe). The global solar irradiance striking a solar cell is estimated using the spectral irradiance model for clear skies SMARTS2. The variation of the common performance namely short circuit current, fill factor, open circuit voltage, and efficiency are shown and discussed. 2. Calculation procedure 2.1. Spectral solar irradiance calculation A large range of atmospheric radiation models has been elaborated by different authors for calculating the spectral solar irradiation [7, 13]. Several of these models have been developed by various climate research centers and are highly complex numerical models utilizing the satellite observations as inputs. A physical spectral model is proposed by Gueymard [10] and called SMARTS2 (Simple Model of Atmospheric Radiative Transfer of Sunshine) is introduced here to examine the global solar radiation variation on the thin film solar cells output. It can be used in a variety of applications to predict full terrestrial spectra under any cloudless atmospheric condition. It gained acceptance in both the atmospheric and engineering fields due to its low number of inputs, ease of use, to its versatility, execution speed, and various refinements. It can calculate punctual estimations of spectral irradiances using as input parameters the local geographic coordinates, atmospheric water vapor content, atmospheric pressure
110
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
and aerosol optical thickness. SMARTS2 is used to generate the global component of the solar spectra for the site of Setif (36.18°N, 5.41°E, 1081m) on a horizontal surface which is characterized by a clear sky most of the time. 2.2. Solar cell parameters calculation The fill factor and the conversion efficiency Ș of the solar cell are associated through:
FF
Voc I sc Pi S
(1)
Where Pi is the incident irradiation in W/m2 and is given by:
Pi E ( ) d
(2)
0
With ( Ȝ is the spectral irradiance, S is the area of the device, Isc is the short circuit current and Voc is the open circuit voltage. The fill factor FF is defined as [9]:
FF Where
v oc
voc ln voc 0.72 voc 1 V oc kT n q
(3)
(4)
The open circuit voltage is given by:
Voc n
kT I ph ln 1 q Is
(5)
The ideality factor, n, and the saturation current, Is, are computed from the I-V characteristics using an approach that involves the use an auxiliary function and a computer fitting routine [15]. The short circuit density Jsc of device, which is the value of the photocurrent density, is directly linked to the spectral irradiance ( Ȝ and can be calculated as:
J sc E() SR() d
(6)
111
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
Where ( Ȝ is the energy of the incident light and SR (Ȝ is the measured spectral response at a given wavelength, Ȝ. Figure 1 shows the measured spectral response of the different thin film solar cells considered in this study. It is clear that each technology has a characteristic spectral response and an effective spectral range. Nanocrystalline silicon (nc-Si: H) cells respond in the range 400-1100nm, while CdTe cells respond in the range 400-900nm. 0,7
Spectral Responce (A/M)
0,6
CdTe 0,5 0,4
nc-Si-H
0,3 0,2 0,1 0,0 0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
1,1
1,2
Wavelength (μm)
Figure 1: Spectral response of the different thin film solar cells [2-16].
112
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
3. Results and discussion The global solar irradiance is calculated at Setif (36.11°N, 5.25°E, and 1081m) on a horizontal surface by varying one environmental parameter and maintaining the others fixed (AM1.031, albedo=0.1 and turbidity=0.1), using SMRTS2. Then for each value of the environmental parameter in the study, we calculated the short circuit current, the open circuit voltage, the fill factor and the conversion efficiency of the CdTe and microcrystalline silicon solar cells. The variations of global spectral irradiance as a function of wavelength under the influence of precipitable water vapor amount are presented in Figure 2. We note a decrease in solar irradiance when water vapor increases, mainly in the infrared region because in this region the water vapor is the most important absorber. The main water vapor absorption bands of solar radiation can be seen at 0.72 DQGȝP%H\RQG ȝPWKHWUDQVPLVVLRQRIWKHDWPRVSKHUHLVYHU\ORZGXHWRDEVRUSWLRQE\ZDWHUYDSRU
Global solar irradiance (W/m2nm)
2,0
WV0.5 WV1 WV2 WV3 WV4
WV= 4cm
1,5
WV= 3cm 1,0
WV= 2cm WV= 1cm
0,5
0,0 250
WV= 0.5cm
AM=1.031 Albd=0.1 turb=0.1 500
750
1000
1250
1500
1750
2000
Wavelength(nm)
Figure 2: Global spectral irradiance as a function of wavelength for different values of water vapor at Setif.
Figure 3 shows the influence of water vapor on the efficiency of the different considered solar cells. The efficiency increases with increasing water vapor, so that the output current is increased. Increasing water vapor in the atmosphere reduces the available irradiance and consequently the short circuit current. The output current is reduced but in different proportion for each type of cell according to the situation and shape of the spectral response. The reduction in the short circuit current due to increasing water vapor is 3.15% and 2.38% respectively for CdTe and (nc-Si-H) solar cells when the water vapor amount increases from 0.5 to 4 cm. The current of the (nc-Si-H) solar cell is subjected to a larger reduction than that of CdTe because the spectral response of (nc-Si-H) solar cell covers a larger area than does CdTe. A general summary of the variation of the short current, open circuit voltage and fill factor as function of the water vapor are illustrated in Table 1.
113
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
15 14
CdTe
AM=1.031 Albd=0.1 turb=0.1
Efficiency (%)
13 12 11 10
nc-Si-H
9 8 7 0
1
2
3
4
5
Water Vapor (cm)
Figure 3: Efficiency as function of water vapor on a horizontal surface under global irradiance
Table 1: Effect of the water vapor on the CdTe and nc-Si: H solar cells parameters for global solar irradiance CdTe Solar Cell
(nc-Si-H ) Solar Cell
Water Vapor
Jsc (mA/cm²)
Voc (V)
FF
Jsc (mA/cm²)
Voc (V)
FF
0.5
25.2265
0.8477
0.75162
27.8132
0.4767
0.7513
1
25.1041
0.8474
0.7516
27.7147
0.4766
0.7512
2
24.9015
0.8469
0.75146
27.5603
0.7464
0.7512
3
24.7280
0.8465
0.74138
27.4090
0.4762
0.7511
4
24.5763
0.8461
0.75130
27.2762
0.4761
0.7510
4. Conclusion The aim of this study is to assess the effect of changes in global solar distribution due to the variation of the water vapor content in the atmosphere; using the spectral irradiance model Smarts2, on different parameters characterizing the performance of CdTe and nc-Si-H solar cells. The calculation of the global component of the solar irradiance show that the solar irradiance received at ground level is not only place and time dependent but also varies in intensity due to the varying seasons. The analysis shows that the circuit current decreases with increasing water vapor for the different types of the thin film solar cells. However, the efficiency increases with increasing water vapor. The effect is greater in CdTe than nc-Si: H solar cell under global irradiance.
114
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
References [1] Ferekides, C.S., U. Balasubramanian, R.Mamazza, V.Viswanahan, H. Zhao and D.L.Morel, CdTe thin film solar cells: Device and technology issues. Solar Energy, 77:823-830(2004). [2] Guha. S, Yang .J, High-Efficiency Amorphous Silicon and Nanocrystalline Silicon-Based Solar Cells and Modules, Subcontract Report NREL/SR-520-43191 (May 2008) [3] Meillaud,. F, and al., "Light-induced degradation of thin-film microcrystalline silicon solar cells", in 31th IEEE Photovoltaic Specialist Conference. Lake Buena Vista, FL, USA, (2005). [4] Gottschalg, R., D.G. Infield, M.J. Kearney, "Influence of Environmental Conditions on Outdoor Performance of Thin Film devices". In: proceedings of the 17th European photovoltaic Solar Energy Conference, Munich (WIP- Munich), pp: 769-799 (2001). [5] Gottschalg, R., Bett, T.R., Infield, D.G., Kearney M.J., "The effect of spectral variations on the performance parameters of single and double junction amorphous silicon solar cells", Solar Energy Materials & Solar Cells 85 , 415–428 ( 2005). [6] Ellingson, R.G, and Fourquart, Y., "The Intercomparison of Radiation Codes in Climate Models: an Overview". Journal of Geophysical Research, 96, D5, pp. 8925-8927( 1991). [7] Bird, R.E. and Hulstron, R. L., "Extensive modelled solar spectral data sets with solar cell analysis", Tech. rep. SERI / IR- 215-1598, Solar Energy Research Institute, Golden, CO, (1982). [8] Gueymard, C. A., "REST2: High-performance solar radiation model for cloudless-sky irradiance, illuminance, and photosynthetically active radiation – Validation with a benchmark dataset" Solar Energy 82, 272–285 (2008) [9] Gueymard, C.A., , R. George,"Gridded aerosol optical depth climatological datasets over continents for solar radiation modeling". Proceedings of the Solar World Congress. International Solar Energy Society, Orlando, FL, (2005) [10] Gueymard, C., "SMARTS2, Simple Model of the atmospheric Radiative Transfer of Sunshine: Algorithms and performance assessment". Rep. FSEC-PF-270-95, Florida-Solar Energy Center, Cocoa, FL, (1995). [11@*XH\PDUG&HWDO7KHVXQ¶VWRWDODQGVSHFWUDOLrradiance for solar energy applications and solar radiation models". Solar Energy, 76: 423452, (2004). [12] Gueymard, C., "Prediction and Validation of Cloudless Short wave Irradiance Spectra for Horizontal, Titled or Tracking Receivers", Solar Conference, ASES, Denver Co.,( 2006). [13] Gueymard, C. A., D.R. Myers, "Evaluation of conventional and high-performance routine solar radiation measurements for improved solar resource, climatological trends, and radiative modeling", Solar Energy 83, 171–185, (2009). [14] Green, M. A., Solar Cells, Operating Principals, Technology, and System Applications, Prentice-Hall Inc., Englewood Cliffs, (1982). [15] Chegaar M., G. Azzouzi, and P. Mialhe, "Simple parameter extraction method for illuminated solar cells", Solid-State Electronics 50, 1234– 1237, (2006). (1990) 351 – 357 [16] D. l. Morel, C. S. Ferkides, Advanced Processing of -CdTe and CuIn1-x Gax Se2- Based Solar Cells, NREL Technical Report. 520-35092 (Feb. October 2003)
The seventh International Conference on Material Sciences (CSM7)
The Effect of Water Vapor on the Performance of Solar Cells A. Guechia,*, M. Chegaarb, A. Merabeta a
Institute of Optics and Precision Mechanics, Ferhat Abbas University, 19000, Setif, Algeria b Department of Physics, Ferhat Abbas University, 19000, Setif, Algeria [email protected]
Abstract The objective of this study is to determine the effect of variations in global spectral distribution due to the variation of water vapor on the performance of two types of solar cells, nanocrystalline silicon (nc-Si:H) and cadmium telluride (CdTe) using the spectral irradiance model for clear skies SMARTS2 over a typical rural environment in Setif. Water vapor can reduce the amount of sunlight reaching a solar cell, and thereby cause a reduction in the electrical current, fill factor, open circuit voltage. The results indicate that water vapor increase in the atmosphere reduces the short circuit current of the CdTe cell by 3.15% while this reduction is about 2.38% for the (nc-Si:H) cell. The efficiency for both cells increases with increasing water vapor. These findings should be taken into consideration by solar cell engineers for better sizing of these types of solar cells. © 2011 Published by Elsevier B.V. Open access under CC BY-NC-ND license.
Selection and/or peer-review under responsibility of the Organizer. Keywords: CdTe, (nc-Si:H), Solar Cells, Efficiency, Water Vapour, Global Irradiance, Spectral Variation, SMARTS model.
*
Corresponding author: Email: [email protected]
1875-3892 © 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of the Organizer. Open access under CC BY-NC-ND license. doi:10.1016/j.phpro.2011.10.016
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
109
1. Introduction In recent years new thin film technologies have entered the photovoltaic (PV) marketplace and are now available commercially, namely cadmium telluride (CdTe), Copper-Indium-Gallium-Diselenide (CIGS), and hydrogenated amorphous silicon (a-Si-H). These technologies exhibit a steadily improving efficiency and are potentially cheap to produce. Today CdTe is one of the leading thin film photovoltaic materials due to the optimum band gap of 1.5 eV for the efficient photo conversion and high optical absorption coefficient (tKLFNQHVVRIDSSUR[LPDWHO\ȝPZLOODEVRUEQHDUO\RIWKe incident solar radiation) [1]. The amorphous silicon/nanocrystalline silicon (a-Si/nc-Si) tandem solar cell is a promising candidate for use as the next-generation of thin film solar cells. Compared to other thin-film technologies currently under development and being presently industrialized (CIGS, CdTe), silicon thin-films have the key advantage of using silicon as raw material that is non-WR[LF DQG ZLGHO\ DYDLODEOH LQ WKH HDUWK¶V FUXVW $OWKRXgh this material has a complex nanostructure, its optical properties have a marked crystalline characteristic. The band gap of the nanocrystalline areas should be around 1.1 eV; while for the amorphous, it is around 1.7-1.8 eV [2]. With these band gaps, the ncSi: H diode should have a much higher forward current density than the CdTe. This implies the spectral absorption of nanocrystalline silicon covers a much larger range. Nanocrystalline silicon absorbs light coming from a wider spectral range, extending to 1100 nm [2]. Furthermore, the nc-Si: H solar cell is reported to be largely stable against light induced degradation [3]. Another advantage of the (nc-Si: H) and CdTe technologies is the flexibility with regards to the method of manufacture. Global solar radiation at surface level is an important parameter in designing systems employing solar energy, such as high temperature heat engines, high intensity solar photovoltaic cell, building designing, horticulture, etc. Manufacturers report photovoltaic module power output at standard testing conditions (STC), which correspond to 1000 W/m2, 25°C, air mass 1.5 and normal incidence. In real operating conditions however, the module output is strongly affected by various environmental conditions such as irradiance, temperature, spectral effects. Furthermore the impact of each climatic factor on the energy production varies according to the module technology in use [4]. The performance of solar cells is influenced by the solar radiation at ground level that is not only place and time dependent but also varies in intensity and spectrum due to varying atmospheric parameters as turbidity, water vapor, air mass, and albedo. The effect of the variations of the solar spectrum on the performance of the different photovoltaic devices is not yet quantified on a large scale and few works have been published [5]. This is mainly due to the difficulty to obtain spectral measurements especially for developing countries for not being able to afford the necessary equipment. The aim of this study is to evaluate the effect of changes in spectral distribution of global irradiation due to the variation of atmospheric parameters such as water vapor content on the performance of two types of solar cells, nanocrystalline silicon (nc-Si-H) and cadmium telluride (CdTe). The global solar irradiance striking a solar cell is estimated using the spectral irradiance model for clear skies SMARTS2. The variation of the common performance namely short circuit current, fill factor, open circuit voltage, and efficiency are shown and discussed. 2. Calculation procedure 2.1. Spectral solar irradiance calculation A large range of atmospheric radiation models has been elaborated by different authors for calculating the spectral solar irradiation [7, 13]. Several of these models have been developed by various climate research centers and are highly complex numerical models utilizing the satellite observations as inputs. A physical spectral model is proposed by Gueymard [10] and called SMARTS2 (Simple Model of Atmospheric Radiative Transfer of Sunshine) is introduced here to examine the global solar radiation variation on the thin film solar cells output. It can be used in a variety of applications to predict full terrestrial spectra under any cloudless atmospheric condition. It gained acceptance in both the atmospheric and engineering fields due to its low number of inputs, ease of use, to its versatility, execution speed, and various refinements. It can calculate punctual estimations of spectral irradiances using as input parameters the local geographic coordinates, atmospheric water vapor content, atmospheric pressure
110
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
and aerosol optical thickness. SMARTS2 is used to generate the global component of the solar spectra for the site of Setif (36.18°N, 5.41°E, 1081m) on a horizontal surface which is characterized by a clear sky most of the time. 2.2. Solar cell parameters calculation The fill factor and the conversion efficiency Ș of the solar cell are associated through:
FF
Voc I sc Pi S
(1)
Where Pi is the incident irradiation in W/m2 and is given by:
Pi E ( ) d
(2)
0
With ( Ȝ is the spectral irradiance, S is the area of the device, Isc is the short circuit current and Voc is the open circuit voltage. The fill factor FF is defined as [9]:
FF Where
v oc
voc ln voc 0.72 voc 1 V oc kT n q
(3)
(4)
The open circuit voltage is given by:
Voc n
kT I ph ln 1 q Is
(5)
The ideality factor, n, and the saturation current, Is, are computed from the I-V characteristics using an approach that involves the use an auxiliary function and a computer fitting routine [15]. The short circuit density Jsc of device, which is the value of the photocurrent density, is directly linked to the spectral irradiance ( Ȝ and can be calculated as:
J sc E() SR() d
(6)
111
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
Where ( Ȝ is the energy of the incident light and SR (Ȝ is the measured spectral response at a given wavelength, Ȝ. Figure 1 shows the measured spectral response of the different thin film solar cells considered in this study. It is clear that each technology has a characteristic spectral response and an effective spectral range. Nanocrystalline silicon (nc-Si: H) cells respond in the range 400-1100nm, while CdTe cells respond in the range 400-900nm. 0,7
Spectral Responce (A/M)
0,6
CdTe 0,5 0,4
nc-Si-H
0,3 0,2 0,1 0,0 0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
1,1
1,2
Wavelength (μm)
Figure 1: Spectral response of the different thin film solar cells [2-16].
112
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
3. Results and discussion The global solar irradiance is calculated at Setif (36.11°N, 5.25°E, and 1081m) on a horizontal surface by varying one environmental parameter and maintaining the others fixed (AM1.031, albedo=0.1 and turbidity=0.1), using SMRTS2. Then for each value of the environmental parameter in the study, we calculated the short circuit current, the open circuit voltage, the fill factor and the conversion efficiency of the CdTe and microcrystalline silicon solar cells. The variations of global spectral irradiance as a function of wavelength under the influence of precipitable water vapor amount are presented in Figure 2. We note a decrease in solar irradiance when water vapor increases, mainly in the infrared region because in this region the water vapor is the most important absorber. The main water vapor absorption bands of solar radiation can be seen at 0.72 DQGȝP%H\RQG ȝPWKHWUDQVPLVVLRQRIWKHDWPRVSKHUHLVYHU\ORZGXHWRDEVRUSWLRQE\ZDWHUYDSRU
Global solar irradiance (W/m2nm)
2,0
WV0.5 WV1 WV2 WV3 WV4
WV= 4cm
1,5
WV= 3cm 1,0
WV= 2cm WV= 1cm
0,5
0,0 250
WV= 0.5cm
AM=1.031 Albd=0.1 turb=0.1 500
750
1000
1250
1500
1750
2000
Wavelength(nm)
Figure 2: Global spectral irradiance as a function of wavelength for different values of water vapor at Setif.
Figure 3 shows the influence of water vapor on the efficiency of the different considered solar cells. The efficiency increases with increasing water vapor, so that the output current is increased. Increasing water vapor in the atmosphere reduces the available irradiance and consequently the short circuit current. The output current is reduced but in different proportion for each type of cell according to the situation and shape of the spectral response. The reduction in the short circuit current due to increasing water vapor is 3.15% and 2.38% respectively for CdTe and (nc-Si-H) solar cells when the water vapor amount increases from 0.5 to 4 cm. The current of the (nc-Si-H) solar cell is subjected to a larger reduction than that of CdTe because the spectral response of (nc-Si-H) solar cell covers a larger area than does CdTe. A general summary of the variation of the short current, open circuit voltage and fill factor as function of the water vapor are illustrated in Table 1.
113
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
15 14
CdTe
AM=1.031 Albd=0.1 turb=0.1
Efficiency (%)
13 12 11 10
nc-Si-H
9 8 7 0
1
2
3
4
5
Water Vapor (cm)
Figure 3: Efficiency as function of water vapor on a horizontal surface under global irradiance
Table 1: Effect of the water vapor on the CdTe and nc-Si: H solar cells parameters for global solar irradiance CdTe Solar Cell
(nc-Si-H ) Solar Cell
Water Vapor
Jsc (mA/cm²)
Voc (V)
FF
Jsc (mA/cm²)
Voc (V)
FF
0.5
25.2265
0.8477
0.75162
27.8132
0.4767
0.7513
1
25.1041
0.8474
0.7516
27.7147
0.4766
0.7512
2
24.9015
0.8469
0.75146
27.5603
0.7464
0.7512
3
24.7280
0.8465
0.74138
27.4090
0.4762
0.7511
4
24.5763
0.8461
0.75130
27.2762
0.4761
0.7510
4. Conclusion The aim of this study is to assess the effect of changes in global solar distribution due to the variation of the water vapor content in the atmosphere; using the spectral irradiance model Smarts2, on different parameters characterizing the performance of CdTe and nc-Si-H solar cells. The calculation of the global component of the solar irradiance show that the solar irradiance received at ground level is not only place and time dependent but also varies in intensity due to the varying seasons. The analysis shows that the circuit current decreases with increasing water vapor for the different types of the thin film solar cells. However, the efficiency increases with increasing water vapor. The effect is greater in CdTe than nc-Si: H solar cell under global irradiance.
114
A. Guechi et al. / Physics Procedia 21 (2011) 108 – 114
References [1] Ferekides, C.S., U. Balasubramanian, R.Mamazza, V.Viswanahan, H. Zhao and D.L.Morel, CdTe thin film solar cells: Device and technology issues. Solar Energy, 77:823-830(2004). [2] Guha. S, Yang .J, High-Efficiency Amorphous Silicon and Nanocrystalline Silicon-Based Solar Cells and Modules, Subcontract Report NREL/SR-520-43191 (May 2008) [3] Meillaud,. F, and al., "Light-induced degradation of thin-film microcrystalline silicon solar cells", in 31th IEEE Photovoltaic Specialist Conference. Lake Buena Vista, FL, USA, (2005). [4] Gottschalg, R., D.G. Infield, M.J. Kearney, "Influence of Environmental Conditions on Outdoor Performance of Thin Film devices". In: proceedings of the 17th European photovoltaic Solar Energy Conference, Munich (WIP- Munich), pp: 769-799 (2001). [5] Gottschalg, R., Bett, T.R., Infield, D.G., Kearney M.J., "The effect of spectral variations on the performance parameters of single and double junction amorphous silicon solar cells", Solar Energy Materials & Solar Cells 85 , 415–428 ( 2005). [6] Ellingson, R.G, and Fourquart, Y., "The Intercomparison of Radiation Codes in Climate Models: an Overview". Journal of Geophysical Research, 96, D5, pp. 8925-8927( 1991). [7] Bird, R.E. and Hulstron, R. L., "Extensive modelled solar spectral data sets with solar cell analysis", Tech. rep. SERI / IR- 215-1598, Solar Energy Research Institute, Golden, CO, (1982). [8] Gueymard, C. A., "REST2: High-performance solar radiation model for cloudless-sky irradiance, illuminance, and photosynthetically active radiation – Validation with a benchmark dataset" Solar Energy 82, 272–285 (2008) [9] Gueymard, C.A., , R. George,"Gridded aerosol optical depth climatological datasets over continents for solar radiation modeling". Proceedings of the Solar World Congress. International Solar Energy Society, Orlando, FL, (2005) [10] Gueymard, C., "SMARTS2, Simple Model of the atmospheric Radiative Transfer of Sunshine: Algorithms and performance assessment". Rep. FSEC-PF-270-95, Florida-Solar Energy Center, Cocoa, FL, (1995). [11@*XH\PDUG&HWDO7KHVXQ¶VWRWDODQGVSHFWUDOLrradiance for solar energy applications and solar radiation models". Solar Energy, 76: 423452, (2004). [12] Gueymard, C., "Prediction and Validation of Cloudless Short wave Irradiance Spectra for Horizontal, Titled or Tracking Receivers", Solar Conference, ASES, Denver Co.,( 2006). [13] Gueymard, C. A., D.R. Myers, "Evaluation of conventional and high-performance routine solar radiation measurements for improved solar resource, climatological trends, and radiative modeling", Solar Energy 83, 171–185, (2009). [14] Green, M. A., Solar Cells, Operating Principals, Technology, and System Applications, Prentice-Hall Inc., Englewood Cliffs, (1982). [15] Chegaar M., G. Azzouzi, and P. Mialhe, "Simple parameter extraction method for illuminated solar cells", Solid-State Electronics 50, 1234– 1237, (2006). (1990) 351 – 357 [16] D. l. Morel, C. S. Ferkides, Advanced Processing of -CdTe and CuIn1-x Gax Se2- Based Solar Cells, NREL Technical Report. 520-35092 (Feb. October 2003)