Quality Assessment of PV Systems by Analysis of System Performance

IEA INTERNATIONAL ENERGY AGENCY
PHOTOVOLTAIC POWER SYSTEMS PROGRAMME
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Quality Assessment of PV systems by
Analysis of System Performance
Wilfried van Sark (Utrecht University)
With contributions from Thomas Nordmann (TNC), Achim Woyte (3E),
Panos Moraitis (UU), Bhavya Kausika (UU)
Webinar, 6 November 2015
TASK 13: PERFORMANCE AND RELIABILITY OF PV SYSTEMS

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Who am I
• Wilfried van Sark, PhD
• 30+ years experience in PV
– Cells, processing, modeling
– Luminescent solar concentrators
– Performance analysis
• modules, systems
– Market and policy research

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International Energy Agency of the
PV Power Systems Programme
• 29 members: 24 countries, EC, EPIA/Solar
Power Europe, SEPA, SEIA, Copper
Alliance
• Activities are carried out collaboratively on
a country basis along a number of
technical and non-technical subjects
• Currently, 8 Tasks are active
www.iea-pvps.org

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Present IEA PVPS Tasks
• Task 1 - Exchange and dissemination of information on PV power systems
• Task 2 - Operational performance, maintenance and sizing of PV power systems and
subsystems (concluded 2008)
• Task 3 - Use of PV power systems in stand-alone and island applications (concluded 2004)
• Task 5 - Grid interconnection of building integrated and other dispersed PV systems
(concluded 2001)
• Task 6 - Design and operation of modular PV plants for large scale power generation
(concluded 1997)
• Task 7 - PV power systems in the built environment (concluded 2001)
• Task 8 - Very large scale PV power generation systems
• Task 9 - Deployment of PV technologies: co-operation with developing countries
• Task 10 - Urban Scale PV Applications (concluded 2009)
• Task 11 - PV hybrid systems within mini-grids (2013: combined with Task 9)
• Task 12 - PV environmental, health & safety activities
• Task 13 - PV performance, quality and reliability (2014 - 2017)
• Task 14 - High-penetration of PV systems in electricity grids (2014 – 2017)
• Task 15 - Acceleration of BIPV (start Nov 2014)
• Task 16 – Solar resource management (former SHC Task 46)

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Relevant PVPS Issues Task13
• Scenario work
• Market development and trends
• Policy framework
• Business models
• New technologies and applications
• Urban and rural implementation
• Large scale deployment
• Environmental aspects
• Quality and reliability
• Grid integration

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Task 13: Performance and Reliability
of Photovoltaic Systems
ST 1: Economics of PV System Performance
and Reliability
ST 2: System Performance and Analysis
ST 3: Module Characterisation and
Reliability
ST 4: Dissemination

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Webinar
• Quality assessment of PV systems can
only be properly performed when
performance data is available
• IEA-PVPS Task13 approach
1. detailed data on selected PV systems
across the world
2. statistical analysis of large amounts of
two parameters relevant for performance:
annual yield, performance ratio
Report IEA-PVPS T13-05:2014

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Content
• Motivation
• Work from IEA-PVPS Task 13
– Performance database (small sample)
– Statistical analysis (large sample)
– “Counting the Sun” campaign
• Conclusion

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• PV is becoming a mainstream
energy harvesting option
End 2014:
– 177 GWp capacity
– 1% of global electricity
production
• Optimal performance
required
Motivation
Global PV Evolution
177GW
2014
Have been installed all over the world
1GW
MARK
20 countries have now passed the
IN 2014 THE TOP 3 WORLD COUNTRIES, WHICH ARE ALSO
PART OF THE IEA PVPS PROGRAM WERE:
1
2
3
38,7GW
As of the end of 2014
of cumulative PV systems capacity at the end of 2014
and 5 countries installed at least 1 GW in 2014
(compared to 9 in 2013).and only in 2014
Have been installed in the world
7,9%
7,6%
7,1%
19 COUNTRIES
IN THE WORLD NOW HAVE AT LEAST ENOUGH PV TO COVER
1% OF THEIR ANNUAL ELECTRICITY DEMAND
WITH PV.
TOP3
IEA PVPS COUNTRIES
WITH MORE THAN 1 GW
INSTALLED
NON
IEA PVPS COUNTRIES WITH A
SIGNIFICANT PV MARKET
IEA PVPS COUNTRIES
WITH LESS THAN 1 GW
INSTALLED
1%OF THE WORLD ELECTRICITY GENERATION IS
NOW COVERED WITH PV AND
South-Africa
India
UK
Chile
IEA PVPS
countries
ITALY
GREECE
GERMANY
IEA PVPS snapshot

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• Do we know
“How well is PV serving the world?”
• Do good promises lead to good
performance (= quality)?
Motivation
Without data we cannot
address performance

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Performance in climate zones?
[Peel,2007]

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Motivation
Shade is one reason for
lower performance
(inverter MPP)
0 5 10 15 20 25 30 35
0
1
2
3
4
5
6
7
8
Netting, row shade
Voltage (V)
Current(A)
no shade
3 BPD
6 BPD
12 BPD
20 BPD
60 BPD
[Pannebakker,2014]

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Monitoring Data: What to Measure?
PR
IC
Array capture
losses
IS
System losses
PV array Inverter GridGI
VDC
IDC
PDC
VAC
IAC
PAC
yr
Reference yield
yA
Array yield
yf
System yield
Tamb , T mod , SW
©
[Woyte,2014]
Too complex
for residential
system owner

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Field performance analysis T13
1: Analytical approach:
• collecting and analyzing validated
datasets in public database (e.g.,
monthly PR)
2: Statistical approach:
• collecting huge amounts of system data
from participants and using web
scraping techniques followed by
analyses

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Master DB wwwInterface
userinterface
Performance Data Base T13/2.1/ Topology
(10-2011 - 2017 )
Export
numeric info
plant, several
monitoring
years …
T13 Expert
database
input tool,
since: 5-2011
graphic infos
XY Info
evaluation
direct www
access with
browser
T13
partner
database
input tool
Task 13/2.1
mail
www
www
mail
online since: 10-2011
Quality
Control
Operator
T13/1
mail

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Screen shot input tool

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PVPS
Performance
Data Base
http://www.iea-pvps.org
www.iea-pvps.org

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Pending:
NL, AUS,
IT, GER

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Example of automated analysis in the DB

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Analysing groups of PV systems using filter criteria
 Performance is improved

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Analysing groups of PV systems using filter criteria

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Performance ratio is going up
IEA – PVPS Task 2
[Nordmann, 2007]
German systems:
PR from ~60% to >80%
[Reich, 2012]
Is 90% the maximum?!

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Want to contribute?
• We are always seeking for more data
• Requirements
– Validated operational and system data
– Input using input tool
– Interested: mail me
w.g.j.h.m.vansark@uu.nl

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2: statistical analysis
• Performance has been increasing in the
past decades
• Still, reasons for lower performance
than expected (or promised) are
difficult to detect
– due to insufficient monitoring of
1-5 kWp residential systems in particular

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Statistical approach
data per system size bins (<1 kWp -- >10 MWp)
supplied per region/country:
• Annual Yield (AC)
kWh/y/installed kWp as a function of location, climate
zone
• Annual average performance ratio PR
Use measured irradiance from local sensor or satellite
data
• Degradation rate
For plants in the field for a 5-year period (if possible)
Focus on annual data is what the customer needs to know

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Example:
Statistical analysis Italy
• Example size bin: 10-100
kWp, installed in 2007, full
year measurements for
2008-2012 (5 years)
• Courtesy: Francesca Tilli
(GSE) [T13 participant]

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Italy
All years averaged
Larger systems
somewhat better
performing
# systems
North: 58
Central: 48
South: 48

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2: statistical analysis:
data mining
• Market is introducing web
tools for system owners to
share monitor data, e.g.,
SolarLog
• Objective is to analyze PV
performance data
obtained by web scraping
techniques that collect and
organize these data
automatically in databases
• “What you see, is what you
can extract” [Legal]
• Developed Python scripts
• Accuracy?

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Results
Country Samples System Size kWp
Netherlands 728 11.1
Germany 764 15.6
Italy 532 13.1
France 325 15.1
Belgium 565 6.5
GER ITA NL FRA BEL
P
M
A

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Results: annual yield
Yearly variation between 2011-2013 from 2-11%
NL GER BEL ITA FRA
2011
2012
2013

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Country 2011 2012 2013
Germany
North 979±153 937±126 882±109
South 1081±154 1044±121 992±125
France
North 1030±362 993±201 959±154
South 1099±96 1092±224 1103±166
Italy
North 1219±170 1177±157 1094±148
South 1352±113 1337±199 1288±203
South:
+6-18%
FRA GER ITA
Annual yield (kWh/kWp) ±(stdev)

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Results: NL Geographical Variation
Region PR Annual Yield
kWh/kWp
Irradiation
kWh/kWp
Coast 79.3+/-2% 895+/-21 1165
Mainland 77.1+/-2% 833+/-19 1021
Temperature, wind ?

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Annualyield2014
Netherlands
Belgium
Germany
France
Italy
1000 kWh/kWp
Moraitis, Van Sark
PVSC 42, 2015

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GIS mapping of yield 2014

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ongoing
link with climate zones to be done

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Example: “Counting the Sun”
• Dutch Solar Days 2014 (May 12 – May 18)
• Awareness campaign “How well is my system doing”
• Social media, national television show “Kassa”
 >5000 systems spread over the country
 “citizen science”
average weekly yield
33.4 kWh/kWp
considerable spread

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Example: “Counting the Sun”
• Most systems are performing well
• Average performance ratio 0.74±0.10
• NO geographical variation in performance ratio
• Some 10% of participants indicated some form
of shade, performance ratio: 0.70±0.10.
irradiation yield performance ratio

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Conclusions
• Obviously, without DATA one cannot
say anything about PERFORMANCE
(=quality)
• PV system performance is
increasing, however practical
example shows otherwise (PR=0.74)
• Link with climate zones to be
established
(IEC-TC82, standard modifications?)

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Conclusions
Reliability? = continuously high PR
• IEA PVPS Task 13
– Collecting and analyzing data
– From participants
– Statistical analysis, web scraping
• Irradiation data needed (JRC)
Please join or contribute

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Thank you for listening!
Q&A
http://www.iea-pvps.org/index.php?id=57

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Reports by IEA PVPS Task 13
http://www.iea-pvps.org/index.php?id=57
1. Review of Failures of Photovoltaic Module, Report IEA-PVPS T13-01:2014
2. Analytical Monitoring of Grid-connected Photovoltaic Systems - Good Practices for
Monitoring and Performance Analysis, Report IEA-PVPS T13-03: 2014
3. Characterisation of Performance of Thin-film Photovoltaic Technologies, Report IEA-
PVPS T13-02:2014
4. Degradation Behaviour of PV Modules under Different Accelerated Stress Conditions
Based on Stress Conditions Evaluated from Real-time Outdoor Testing, Report IEA-
PVPS T13-04: 2014
5. Analysis of Long-Term Performance of PV Systems - Different Data Resolution for
Different Purposes,, Report IEA-PVPS T13-05:2014

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Quality Assessment of PV Systems by Analysis of System Performance

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