failures of thin-film pv modules: field experience · dacd / isaac / nrel – thin film pv modules...

DACD / ISAAC / NREL Thin film PV modules

1

Failures of thin film PV modules: Field experience

Dr. Thomas Friesen PV Module Group

2NREL

2 DACD / ISAAC / NREL Thin film PV modules

Content

Introduction

Failures of thin film modules in the field

TISO thin film systems

Summary

ISAAC: Trevano


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


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

2/28/13


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


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


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

2/28/13


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


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 !!

2/28/13


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..)

2/28/13


Hot spot in thin film modules (I)

Hot spot caused

the glass

breakage

In unfavourable conditions hot spot can cause fire !!

2/28/13


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

2/28/13


2/28/13


TCO corrosion and delamination

Large area delamination

Causes:

- Potential induced ion migration

- moisture penetration in the module

- production defects Source: www.nacleanenergy.com

2/28/13

http:www.nacleanenergy.com


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

2/28/13


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)

2/28/13


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 !!


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


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 !! ??


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


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

failures of thin-film pv modules: field experience · dacd / isaac / nrel – thin film pv modules...

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