The document describes an experimental investigation of a 1.2 kWp photovoltaic (PV) power plant under different loading conditions. Key findings include: 1) Testing was conducted at loads of 350W, 700W, and 750-1050W to analyze the effect on battery state of charge, voltage, and charging/discharging currents. 2) Under optimal loading of around 38% (455W), good agreement was found between predicted and experimental results for load current (8.54A) and power (455W). 3) Under optimal loading, the battery maintained a state of charge between 79.87-80% and voltage of 47.54-48.47V, indicating

1. December 10, 2013
Performance assessment and experimental investigation of
1.2 kWp PV power plant in different loading conditions
Subhadeep Bhattacharjee, Shubhashish Bhakta, Shantanu Acharya
Department of Electrical Engineering
National Institute of Technology (NIT), Agartala, India
E-mail: subhadeep_bhattacharjee@yahoo.co.in
IVth International Conference on Advances in Energy Research (ICAER 2013), IIT Bombay
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2. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Introduction
 Solar energy is an inexhaustible source of green energy.
 Solar radiation received by earth is 0.8 million kW
 0.1 % of the received radiation with 5 % conversion rate
would generate 40 times electrical energy consumed by
current world
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3. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Different solar energy technologies
• Photovoltaic (PV) system
• Concentrating solar power (CSP)
• Transpired solar collector
or “Solar walls”
• Solar water heater systems
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4. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Why PV system is popular than other solar
technology?
 Requires less space than other
solar technologies for same
amount of power generation
 Direct conversion of solar
energy into electrical energy
 Cost per watt of this
technology is less.
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5. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Typical Stand-alone PV plant
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6. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Experimental PV power plant of 1.2 kWp
Components
PV current, PV
power
PV array
 1.2 kWp PV array
 Battery bank
PCU with 48 V bus
 Inverter
Load
Load current,
Load power
Inverter
Battery charging current
Battery bank
 Load
 Computer for monitoring
Battery discharging current
Block diagram of the PV plant
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7. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Specification of the system
Parameter
PV panel area
Peak power
Open circuit voltage
Short circuit current
Peak power voltage
Peak power current
Battery type
Number of batteries
E.M.F. of each battery
Current of each battery
NOCT
Specification
: 8 m2
: 195 Wp
: 45.5 V
: 5.5A
: 37.5 V
: 5.20 A
: Lead-acid
: 24
:2V
: 400 Ah
: 47 C
1.2 kWp PV Plant
Battery bank
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8. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Simulink model of the system
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9. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
ANN model of the system
 Based on Levenberg-Marquardt algorithm
Battery
charging
current
PV
current
Battery
discharging
current
PV
power
Load
power
Battery
voltage
Load
current
Input layer
Hidden layer
Output layer
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10. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Battery SOC at different loading
 SOC declines at
rate of 0.08 % for
every 10 % loading
80.01
79.97
Battery SOC (%)
79.94
79.90
79.87
79.83
79.80
79.76
79.73
% loading
10
60
79.69
79.66
06
07
08
20
70
09
30
80
10
12
40
90
13
50
100
14
15
16
18
19
Time (hr)
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11. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Battery voltage profile at different loading
48.4
48.0
Battery voltage (V)
 Battery voltage is
reduced from 48.58 to
48.41 V for 10%
loading, 48.43 to 48.10 V
for 20%, 48.29 to 47.79 V
for 30%, 48.14 to 47.47 V
for 40%, 48.00 to 47.16 V
for 50%
47.6
47.2
46.8
46.4
46.0
Loading percentage (%)
10
20
30
60
70
80
45.6
45.2
06
07
08
09
10
12
40
90
13
50
100
14
15
16
18
19
Time (hr)
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12. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Load current and load power
Load current (A)
22
20
18
16
14
Load current (A) at 350 W
Load current (A) at 700 W
Load current (A) at 750-1050 W
12
10
8
6
07:12
08:24
09:36
10:48
12:00
13:12
14:24
15:36
16:48
18:00
14:24
15:36
16:48
18:00
Time (hr)
Load power (W)
1100
1000
900
Load power (W) at 350 W
Load power (W) at 700 W
Load power (W) at 750-1050 W
800
700
600
500
400
300
07:12
08:24
09:36
10:48
12:00
13:12
Time (hr)
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13. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Testing with 350 W
 Average battery charging
current is 1.64 A.
 Average battery
discharging current is 1.90 A
7.2
Battery discharging
4.8
2.4
0.0
13.8
Current (A) Current (A)
Battery charging current is
available for most of the
time.
Battery charging
9.2
4.6
0.0
14.7
PV
9.8
4.9
0.0
Voltage (V)
When average PV current
is 5.46 A
Current (A)
07:12 08:24 09:36 10:48 12:00 13:12 14:24 15:36 16:48 18:00
51.7
Battery
50.6
49.5
48.4
07:12 08:24 09:36 10:48 12:00 13:12 14:24 15:36 16:48 18:00
Time (hr)
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14. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Testing with 700 W
 Average battery charging
current is 0.0049 A.
 Average battery
discharging current is 5.99 A
13.8
Battery discharging
9.2
4.6
0.0
Current (A)
Current (A)
Battery charging current is
available for less time.
Voltage (V)
When average PV current
is 8.10 A
Current (A)
07:12 08:24 09:36 10:48 12:00 13:12 14:24 15:36 16:48 18:00
0.6
Battery charging
0.4
0.2
0.0
PV
13.2
8.8
4.4
0.0
51.00
Battery
50.25
49.50
48.75
07:12 08:24 09:36 10:48 12:00 13:12 14:24 15:36 16:48 18:00
Time (hr)
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15. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Testing with 750-1050 W
When average PV current is
9.54 A
Current (A)
07:12 08:24 09:36 10:48 12:00 13:12 14:24 15:36 16:48 18:00
21.3
Battery discharging
14.2
7.1
 Average battery discharging
current is 10.98 A
3
Battery charging
2
1
0
17.7
PV
11.8
5.9
0.0
49.28
Voltage (V)
 Mean battery charging
current 0.043 A.
Current (A) Current (A)
0.0
Battery
48.40
47.52
46.64
07:12 08:24 09:36 10:48 12:00 13:12 14:24 15:36 16:48 18:00
Time (hr)
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16. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Optimal load current
 Predicted optimal load
current varies between 8.82 A
and 8.93 A.
Average value of predicted
and experimental optimal load
current is 8.60 A and 8.54 A
respectively
Experimental
Predicted
8.8
Load current (A)
Experimental optimal load
current varies between 8.13 A
and 8.40 A.
9.0
8.6
8.4
8.2
8.0
0
10
20
30
40
50
60
Time (min)
70
80
90
100
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17. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Optimal load power
 Corresponding minimum
values are 428.85 W and
434.76 W respectively.
490
Experimental
Predicted
480
Load power (W)
 Maximum predicted and
experimented load power are
476.66 W and 487.37 W
respectively
470
460
450
440
Predicted and experimental
mean values of load powers are
453.87 W (37.82 %) and
455.17 W (37.93 %)
430
0
10
20
30
40
50
60
70
80
90
100
Time (min)
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18. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Battery charging current in optimal loading
condition
Experimental battery
charging current ranges from 0
A to 13.26 A with mean value
of 4.12 A
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Battery charging current (A)
 Predicted battery charging
current varies from 0.03 A to
13.79 A with mean value of
4.13 A
Experiment
Predicted
12
10
8
6
4
2
0
0
10
20
30
40
50
60
70
80
90
100
Time (min)
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19. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Battery discharging current in optimal loading
condition
Experimental battery
discharging current ranges from
0 A to 4.90 A with average value
of 4.12 A
Experimental
Predicted
5
Battery discharging current (A)
 Predicted battery discharging
current varies from -1.54 A to
4.50 A with average value of
0.42 A
4
3
2
1
0
-1
-2
0
10
20
30
40
50
60
70
80
90
100
Time (min)
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20. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
Conclusion
A very good agreement is found between ANN based predication
and experimental investigation under optimal loading conditions.
The PV system sustains about 38 % loading and with mean load
current of 8.54 A. Beyond this loading will increase the battery
discharging current.
From simulation results under optimal loading condition, the
battery maximum and minimum SOC are obtained as 80 % and
79.87 % respectively with a mean value of 79.93 %.
The maximum and minimum battery voltages are found to 48.47
V and 47.54 respectively with average value of 47.84 V.
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21. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
References
Chen, N., Zhang, X., Bai, Y. and Zhang, H. (2012) Environmental friendly PV power
plant, International Conference on Future Energy, Environment, and Materials, 16, pp.32-37.
Linden, D. (2002) Handbook of batteries and fuel cells, Mcgraw-Hill, New York.
Mahmoud, M.M. (1989) Individual Applications of Photovoltaic Power Systems, Royal Scientific
Society Amman, Jordan.
Zahedi, A. (1998) Development of an electrical model for a PV/battery system for performance
prediction, Renewable Energy, 15(1998), pp. 531-534.
Posadillo, R. and Lopez Luque, R. (2007) A sizing method for stand-alone PV installations with
variable demand, Renewable Energy, 33(2008), pp. 1049-1055.
IEEE 1361TM-2003 IEEE Guide for Selection, Charging, Test and Evaluation of Lead-Acid
Batteries Used in Stand-Alone Photovoltaic (PV) Systems.
Hara, R., Kita, H., Tanabe, T., Sugihara, H., Kuwayama, A. and Miwa, S. (2009) Testing the
technologies, IEEE Power Energy Magazine, 7(3), pp. 77-85.
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22. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
References continued…
Yoshimoto, K., Nanahara, T. and Koshimizu, G. (2006) New control method for regulating
state-of-charge of a battery in hybrid wind power/battery energy storage system, Proceedings IEEE
PES Power Systems conference and Exposition, pp. 1244-1251.
https://eosweb.larc.nasa.gov/sse/
Mahmoud, M.M. (1989) Individual Applications of Photovoltaic Power Systems, Royal Scientific
Society Amman, Jordan.
Kalogirou, S.A. (2000) Artificial neural networks in renewable energy systems applications: a
review, Renewable and Sustainable Energy Reviews, 5, pp. 373-401.
Balzani, M. and Reatti, A. (2005) Neural Network Based Model of a PV Array for the Optimum
Performance of PV System , Proceedings PhD Research in Microelectronics and Electronics
Conference, 2, pp. 123-126.
Sulaiman, S.I., Abdul Rahman, T.K. and Musirin, I. (2008) ANN-based Technique with Embedded
Data Filtering Capability for Predicting Total AC Power from Grid-connected Photovoltaic
System, 2nd International Power Engineering and Optimization Conference (PEOCO2008), pp.
272-277
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23. December 10, 2013
Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
References continued…
Sulaiman, S.I., Musirin, I. and Abdul Rahman, T.K. (2008) Prediction of Total AC Power Output
from a Grid-Photovoltaic System Using Multi-Model ANN, 7th WSEAS International Conference on
Application of Electrical Engineering (AEE08), pp. 118-123..
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Performance assessment and experimental investigation of 1.2 kWp PV power plant in different loading conditions
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