Sunpo Sunpow wer C60 C60 IV IV Curv Curve e Characterization 2013 09 04 Peter Pe ter Sun & Ahtha Ahthavan van Sures Sureshkum hkumar ar
Motivation •
Improving accuracy of array simulation results
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Creating a calibrated pyranometer
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Understanding Understanding net consequences of array array cut decisions and lamination Understanding Understanding relationship of angle dependence of solar cell-lamination combination
Test Plan •
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Measure Measure Sunpower Sunpower C60 IV curves curves at at a site site of known irradiance, at 15min intervals intervals Orient 2 cells towards the sun to eliminate angle dependence, results to be averaged averaged Compare results between oriented horiz. oriented cell and oriented cells Orient all 3 cells horizontally horizontally to determine statistical variation between cells
C60 Manufacturer Specifications Sunpower provides provides specifications specifications for a full, bare cell, at standard testing conditions. The published expected IV curves are most likely simulated.
Differences •
Lamination
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{Peter please elaborate}
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Size –
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New rectangular size: 31.75 x 125 mm Decrease in area-toperimeter results in degradation of performance 32.57mm2:1mm to 12.66mm2:1mm
Expected Results •
Modeling a PV cell using the below equation, as per The Winning Solar Car, the following dependencies are: –
Rs, Rsh = f(Voc, Isc)
–
IL, IS = f(n, Voc, Isc)
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If power/current prop. to size only, then at STC, new peak power, peak current, short-circuit current per cell: •
0.86 W
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1.51 A
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1.62 A IL – potential potential current current sunlight creates creates IS – diode saturation saturation current current RSH – shunt resistance resistance RS – internal internal series resistance resistance n – model model paramet parameter er (1.5 for silicon cells)
Testing esting Location Location
UTM gratefully gratefully allowed us access to pyranometer pyranomet er readings at their their local meteorology meteor ology station, as well as gain access ac cess to the local vicinity to correlate PV measurements with locally measured irradiance values.
Testing esting Location Location
UTM
Setup External programming input
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Output
PV
PV
Custom waveform generator
+
+
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Current Sensing Source output inputs +
HP 6060B Electronic Load
USB Input
c l i p
Ch A Laptop
USB
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Ch B
Oscilloscope
Setup
Controlling the Electronic Load •
A programmable input in the back of the HP 6060B electronic load allows the user to control the current going through the 6060B whilst in Constant Current mode.
Constant Current Control 2.5 2 ) A ( t n e r r u C
1.5 1 0.5 0
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Any waveform generator can be used. The particular waveform generator, the Syscom Syscomp p CGR-101, CGR-101, can can only output up to ±3V. ±3V. The 6060B will scale the input voltage using a 0.6 scaling factor if the range is specified to be 6A
0
0 .5
1
1.5
Time(s)
A sawtooth waveform waveform between between 0-3V was was defined, to enable a sweep of current through the PV cell. The current will be limited by the current that the PV can output, regardless of the current setting.
2
RESUL RESULTS TS – SINGLE, SINGLE, HORIZ. HORIZ. CELL
tek0066ALL.csv 1.28
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1.24 ) V 1.22 ( e g a t l o V 1.2
Unfortunately, majority of collected data was not useful.
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tek0066ALL.csv 0.3
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0 Time (s)
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Electronic Electronic load was providing providing weak signals. tek0066ALL.csv n value = 1.650287e+03
) I ( t n e r r u C
0.3 0.25 0.2
) A ( t n e r r u C
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0.2 0.15 0.1 0.05
0.1 0.05
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0 -0.05 -0.1
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Voltage (V)
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tek0072ALL.csv 0.7
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0.5 ) V 0.4 ( e g a t l o V 0.3
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tek0072ALL.csv 1.2
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Correction made, but clouds rolled in conveniently. A few measurements were made, but could not be correlated to irradiance values since irradiance values are averaged over 15min intervals, and irradiance fluctuated greatly.
) 0.6 I ( t n e r r u C 0.4
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-0.2
tek0072ALL.csv n value = 2.09429 1.2 1
n=1
0.8
n=1.5 n=2
0.6 ) A ( t n 0.4 e r r u C 0.2 0 -0.2 -0.4
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0. 3 0.4 Voltage (V)
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Raw data
IV curve w/ fitted param.
Filtered
IV curve w/ arb. n-value
tek0069ALL.csv n value = 2.08055
tek0072ALL.csv n value = 2.09429
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0.6 ) A ( t n 0.4 e r r u C 0.2
0.6 ) A ( t n 0.4 e r r u C 0.2
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Orientation: Horizontal Sunlight: Bright (irradiance unknown) Params: -Voc: 0.6138 V -Isc: 1.1463 A -n: 2.0805
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0.3 0.4 Voltage (V)
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Comment: Sporadic, intensity sunlight allow us to acquire this data. Note the the high n-value as compared to 1.5 typically assumed for a silicon cell. Results on right is variable due
0. 7
tek0069ALL.csv Pmax = 0.450849 W, Imax = 1.00189 A, V max = 0.45
tek0072ALL.csv Pmax = 0.424867 W, Imax = 0.944148 A, V max = 0.45
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) 0.2 W ( r e w o P 0.1
) 0.2 W ( r e w o P 0.1
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0.4 Current (A)
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0.4 Current (A)
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2-CELL STRING
tek0068ALL.csv 1.3 1.2 1.1 1 ) V 0.9 ( e g a t l o 0.8 V
0.7 0.6 tek0068ALL.csv 1.6
0.5 0.4 -2
1.4 -1.5
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0 Time (s)
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2 1.2 1 ) I ( t 0.8 n e r r u C 0.6
0.4 0.2 0 -0.2
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tek0068ALL.csv 1.6 1.4 1.2 1 ) A ( 0.8 t n e r r u 0.6 C 0.4 0.2 0 -0.2 0. 4
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0. 8 0.9 Voltage (V)
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tek0071ALL.csv 1.8 1.6 1.4 1.2 1 ) A ( t n 0.8 e r r u C 0.6 0.4 0.2 0 -0.2
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0. 6 0. 8 Voltage (V)
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tek0073ALL.csv n value = 1.86641
tek0073ALL.csv Pmax = 0.190549 W, Imax = 0.200578 A, V max = 0.95 max max
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0.2 0.15 ) A ( t n e r r u C
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) 0.1 W ( r e w o P 0.05
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0.1 0.15 Current (A)
Attempted to model IV curve from 2 cells just to be able to generate estimate of peak power. This was taken during shady conditions, so the SNR was low and the resulting power is very low.
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