Photovoltaic Environmental
Performance and Reliability (PEPER)
Project Objectives:
• Monitor performance of grid-tied PV systems
• Report Energy Yields and Degradation Rates
• Evaluate new PV system technologies
Principal Investigator for Part 1: Alex Cronin
Students: Adria Brooks, Tucker Bundgard, Alex Hickey, Daniel Cormode,
Deanna Lewis, Nick Davidson, Ryan Price, Vincent Lonij, Steve Pulver
Collaborators:
Tucson Electric Power, AZRISE, Biosphere 2, SOLON Corporation,
NREL, University of Arizona Graduate College, Science Foundation Arizona,
NASA Space Grant Consortium
TEP PV test yard
4350 E. Irvington Rd.
utility grade AC kwh meter
and custom DC current and voltage monitors
Sunpower system DC current and voltage monitors
Data loggers from JK microsystems
Tours: we’ve had over 1,500 visitors since 2009,
And given public lectures to over 6,000 people
AC Output every minute shown for 2 days:
Data on-line at:
www.UAPV.org
Daily output from a 1.5 kW PV system
Yf = 5.3 h/day = 1935 h/yr
Yf = “final yield” is defined in IEC standard 61724.
TF
TF
TF
TF
TF
TF
TF
TF
Comparison of final yields in 6 places
Degradation Rates for 20 PV systems
Reference:
Steve Pulver, Daniel Cormode, Alex Cronin, Dirk Jordan, Sarah Kurtz,
Ryan Smith, “Measuring Degradation Rates Without Irradiance Data”,
35th IEEE Photovoltaics Specialists Conference, Honolulu, HI (2010).
Temperature and DC Voltage
DC Voltage vs Temperature
Measured Efficiency for 9 systems
Mutual Shading
 Large de-rating
Reference:
Niket Thakkar, Alex Cronin, Daniel Cormode, Vincent Lonij, “A Simple
Nonlinear Model for the Effect of Partial Shade”, 35th IEEE
Photovoltaics Specialists Conference, Honolulu, HI (2010).
S1
S2
model
S1
S2
model
Reference:
Niket Thakkar, Alex Cronin, Daniel Cormode, Vincent Lonij, “A Simple
Nonlinear Model for the Effect of Partial Shade”, 35th IEEE
Photovoltaics Specialists Conference, Honolulu, HI (2010).
S1
S2
model
Reference:
Niket Thakkar, Alex Cronin, Daniel Cormode, Vincent Lonij, “A Simple
Nonlinear Model for the Effect of Partial Shade”, 35th IEEE
Photovoltaics Specialists Conference, Honolulu, HI (2010).
Extrapolations using our non-linear
model of mutual shading.
Shade de-rating
Optimized kwh/acre
Reference:
Niket Thakkar, Alex Cronin, Daniel Cormode, Vincent Lonij, “A Simple
Nonlinear Model for the Effect of Partial Shade”, 35th IEEE
Photovoltaics Specialists Conference, Honolulu, HI (2010).
Heuristic for mutual shading:
get a clear view of the sky from the bottom of each module.
Plans
• Publish yield and efficiency statistics for PV models
• Evaluate PV Performance Models:
CEC 5-parameter model
Sandia / King Model
PVsyst / PVUSA
SAM (NREL) Model
• Collaborate more with NREL, SANDIA, SunPower,
Semprius, SolFocus, Solindra, SOLON, Global Solar,
TEP and Biosphere2
Photovoltaic Environmental
Performance and Reliability (PEPER)
Project Objectives:
• Monitor performance of grid-tied PV systems
• Report Energy Yields and Degradation Rates
• Evaluate new PV system technologies
Principal Investigator for Part 1: Alex Cronin
Students: Adria Brooks, Tucker Bundgard, Alex Hickey, Daniel Cormode,
Deanna Lewis, Nick Davidson, Ryan Price, Vincent Lonij, Steve Pulver
Collaborators:
Tucson Electric Power, AZRISE, Biosphere 2, SOLON Corporation,
NREL, University of Arizona Graduate College, Science Foundation Arizona,
NASA Space Grant Consortium
Photovoltaic Environmental
Performance and Reliability (PEPER)
Project Objectives:
• High-quality Irradiance data
• Atmospheric Science and Power Forecasting
Principal Investigator for Part 2: Bill Conant
Students: Anna Woschuitz
Collaborators:
Tucson Electric Power, NREL
Photovoltaic Environmental
Performance and Reliability (PEPER)
Project Objectives:
• Develop an accurate temperature measurement system for
monitoring modules at the TEP Yard;
• Evaluate the performance of TF and concentrator modules at TEP
Principal Investigator for Part 3: Raymond K. Kostuk, Jose Castro
Students: Derek Zhang
Collaborators:
Prism Solar Technologies, Global Solar
Comparison of Temperature Sensors
• Thermocouple:
A junction of two different
metals which produce a
voltage related to the
temperature of the
junction.
• Currently at TEP
• Useful range:
−200 °C to +1350 °C
• Thermistor:
Generally made of ceramic
or polymers, the
resistance varies with
temperature
• Useful range:
−90 °C to 130 °C
Greater precision
Thermistor on GSE 45W modules
Thermistor Temperature
Measurement
Vs (+5V)
60.00
Rc
50.00
Resistance [kΩ]
High precision, low
temperature coefficient
resistor:
40.00
30.00
20.00
10.00
Vout
0.00
260
R
Vout  Rc
Vs  Vout
310
Temperature [K]
360
1
 a  b ln( R)  c ln 3 ( R)
T
Concentration Test Setup
•Solar simulator: 300W Xenon-arc lamp
with AM1.5 filter
•Flash I-V curve obtained with source
meter
•Temperature is maintained at 25˚C
•Irradiance referenced with calibrated
silicon detectors
Xenon Arc Lamp
Collimating Lens
PV Cell Under Test
Homogenizing Optics
Concentrating Lens
Irradiance Distribution
on PV Cell
Concentration Test Results
[A]
Fill Factor
Short Circuit Current
0.7
0.65
0.6
0.55
0.5
0.45
0.4
0.2
0.15
0.1
0.05
Concentration Ratio
0
0
[V]
1
2
3
4
Concentration Ratio
0
1
[%]
Open Circuit Voltage
2
3
4
Efficiency
12
0.7
0.65
0.6
0.55
0.5
0.45
0.4
11
10
9
8
Concentration Ratio
0
1
2
3
Concentration Ratio
7
4
0
1
2
3
4
Plans
•
•
•
•
Use Global Solar Cells with Prism Concentrators
Maximize yields by harnessing efficiency non-linearities
UA Students working at Global Solar and Prism Solar Tech.
Calibrate thermistor sensors for high accuracy
temperature measurements;