Failures of Thin-Film PV Modules: Field Experience · DACD / ISAAC / NREL – Thin film PV modules...
Transcript of Failures of Thin-Film PV Modules: Field Experience · DACD / ISAAC / NREL – Thin film PV modules...
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DACD / ISAAC / NREL Thin film PV modules
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Failures of thin film PV modules: Field experience
Dr. Thomas Friesen PV Module Group
2NREL
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Content
Introduction
Failures of thin film modules in the field
TISO thin film systems
Summary
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ISAAC: Trevano
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SUPSI - ISAAC
ISAAC: Institute of Applied Sustainability to the Built Environment
SUPSI: University of Applied Science and Arts of Southern Switzerland
1982: start research on PV modules (outdoor exposure performance)
1983: outdoor test stand
2000: indoor flash simulator
2001: ISO17025 accreditation for indoor performance measurement
2008: new lifetime safety mechanical laboratory
2010: ISO17025 of the SWISS PV Module Test Centre
isaac outdoor stand 2011
Experience by:
Research projects , often problems with NDA !!
Services , sometimes confidentiality under ISO 17025
ISAAC: Laboratorio Lamone 2/28/13
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Source of our information on field failures
SUPSI has no active collection of information
Usually we are contacted by system owners (>75%) or installers, but always when the problems are already huge: more then 20 30% of energy production loss or visual failures (glass breakage, large area delamination)
SUPSI propose to understand the failures causes and future evolution by: Sending photos OK (90% of contacts) Sending module less the 1/3 of the clients send modules (costs!!) Visit on site for less then 10 % of the inquires (costs)
2/3 of the contacts solve the problems with the installers / module manufacturer and we have no further follow up
1/3 send modules and we can collect some more information. Of this 2/3 stop investigation because they arrange the problem solving with the installers
Only few failures are well investigated with causes in the field and on the modules
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Market share of thin film modules
Global annual PV installation by technology Worldwide annual production of thin film PV module technologies
Market share of thin film technologies
Thin film modules have today a market share of 14%
Major installed thin film technologies turned from a-Si before 2000 to CdTe and in the last year CiGS technology gain in importance.
Source: Fraunerhofer Institute for Solar Energy Systems ISE, Photovoltaic report December 11, 2012 2/28/13
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Differences' between TF modules and c-Si modules give different failures
TF module C-Si module
Glass glass Glass foil back sheet
Mechanical design One glass is the substrate (often float)
mostly without frame
(for packaging)
Framed
Photo active zone Some microns > 150 microns
Initial degradation From high to low /
depends on technology Low
Material sensitive to moisture High low
Cell interconnections Laser scribing soldering
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Failures of TF modules in the field
Main failures of thin film modules in the field seems to be from
mechanical nature as glass breakage.
Other issue are hot spots with subsequent mechanical failures
TCO corrosion and delamination is a known problem
Issue is power degradation
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Glass breakage of thin film PV modules
Glass breakage caused by snow load Glass breakage caused hot spots and inappropriate mounting system
Glass chipping during installation and handling can cause glass breakage even some years later !
Glass breakage caused by poor clamping 2/28/13
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2010 pvrw: MiaSole Thin Film Solar
Mechanical damage: hail storm damages
Exceptional hail storms can damage thin film modules, in particular modules with polymer surface and float glass are more sensitive.
2012 near SUPSI: Hail grain diameter up to 40 mm !!
After some weeks delamination !!
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Other glass damages of thin film PV modules
Glass breakage occurred during transportation
lightning strikes in a TF PV module Glass breakage con occur by:
Intrinsic defects from glass (e.g. enclosures) or from coatings laser scribing -- > (hot spot)
Extrinsic defects transportation, handling, clamping (e.g. poor experience of some installers) environmental causes (wind, hail..)
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Hot spot in thin film modules (I)
Hot spot caused
the glass
breakage
In unfavourable conditions hot spot can cause fire !!
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Hot spot in thin film modules (II)
Glass fracture causes hot spots along the crack and risk of overheating of the polymer materials
Partial module stresses caused by
the ice
condensation of water
shadowing
Could be origin of Hot Spots
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TCO corrosion and delamination
Large area delamination
Causes:
- Potential induced ion migration
- moisture penetration in the module
- production defects Source: www.nacleanenergy.com
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http:www.nacleanenergy.com
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Failures caused by production defects
Bus bar to long - safety issue (distance to module edge to low) -- > hot spot
Defects in the glass can
increase risk of hot spots,
glass breakage
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Power degradation of thin film modules
Some installers and PV system owner reports high losses of energy production: Causes could be:
A) High degradation rates of the module power caused by potential induced degradation:
-Sometimes reversible with configuration changes (inverters, grounding ...) - if TCO corrosion occurs not reversible
Power degradation by PID, source PI Berlin B) High degradation rates of the module power caused by manufacturing defects
C) Sometime measurements problems, sensors, initial power values, shadows (growing trees)
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Failure comparison TF modules compared to c-Si modules
TF module C-Si module
Frequency Impact Frequency Impact (relative) power / safety (relative) power / safety
Glass breakage ++ ++ / ++ +- ++ / ++
Delamination TCO +- + / - N/A N/A
Yellowing / browning - - / - + + / -
Hot spot + ++ / ++ +/- + / ++
Potential induced + ++/- + ++/- degradation
This are only relative indication based on our experience !!
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TISO thin film System
delamination
lichens
TISO 3 kW system:
a-Si / single junction ARCO Solar
Power: 3 kWp
Installation: 1988
TISO 0.5 kW system:
a-Si / triple junction CANON
Power: 500 Wp
Installation: 1998 2/28/13
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Long term degradation of TISO PV systems
-0.3% p.J.
-1.3% p.J.
Energy production still OK in 2012 ---- no failures of modules !! ??
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Summary
Glass breakage is the main issue in field
Poor experience of installers (handling, clamping...)
Intrinsic defects of the modules
Hot spot are reason for glass breakage and can be dangerous for fire
TCO corrosion is an issue, but sometimes caused by improper grounding, inverters ... or moisture
Power degradation is can have multiple causes
Potential induced degradation
Caused by poor installation
Bad module
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Thank you !!
bookmarksFailures of thin film PV modules: Field Content SUPSI - ISAAC Hot spot in thin film modulesFailures caused by production defectsTISO thin film SystemSummary