NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by 

Initial results of IEC 628

round robin testi

Peter Hacke and Kent Terwil

NREL, USA

Simon Koch, Thomas Weber, and Juli

PI‐Berlin, DE

Stephan Hoffmann and Michae

Fraunhofer ISE, DE

Sascha Dietrich and Matthias 

Fraunhofer CSP, DE

Gerhard Mathiak

TÜV Rheinland, DE

NREL/PR‐5200‐58378
Two out of three planned crystalline silicon module dedistributed in five replicas each to five laboratories foaccording to the IEC 62804 (draft) system voltage durqualification test for crystalline silicon modules. The were performed in environmental chambers at 60°C, 8humidity, 96 h, and with module nameplate system voto the cells (two modules in each polarity and one conPass/fail results, means, and standard deviations of dthe modules tested as a function of module design anlaboratory are presented and discussed. Preliminary the module designs tested so far indicate the test proto discern susceptibility to potential-induced degradaacceptable consistency from lab to lab. Influence of pvariations in the severity of the test between labs has been distinguishable. 

Abstract
• Testing was performed according to IEC 62804 draft 

“SYSTEM VOLTAGE DURABILITY QUALIFICATION TEST FOR

CRYSTALLINE SILICON MODULES.” The motivation was to

– See if the specified sample size (2 modules per polarity) is ad

considering variations that might exist in shipping modules

– See if possible lab to lab variation in stress levels overly influ

results

• Modules were chosen to be near the pass/fail limit vis-

the 60°C/85%RH/-1000 V 96h stress condition to attempget useful statistics (without ‘censoring’). Said anothewe could have chosen modules that do not degrade at and modules that degrade an extreme amount, and shohow well the test differentiates the two, but such resultwould be less useful.

Introduction
Experiment

• Highlights of round-robin test procedure based on IEC 

– Modules leads shorted and connected to high voltage, module – Neither in-situ nor ex-situ I-V measurements are performed on 

course of the 96 h test

– Leakage current from the active layer/cells to ground may opti

during the testing (most labs did not report) 

– Open market modules chosen (but not necessarily currently sh

specially designed modules

– Electroluminescence measurements are carried out before and – Modules are tested in both polarities (2 each), although testing 

choose to use the modules destined for the known stable pola

• Stress conditions

– Chamber air temperature 60 °C ± 2°C– Chamber relative humidity 85 % ± 5 % RH– Test duration 96 h– Voltage: module nameplate rated system voltage (1000 V), 2 f

module supplied for control, voltage applied during ramps

– Pass criterion: both modules of a tested polarity must show < 5

degradation and pass IEC 61215 ed. 2 visual inspection criteri
Experiment

• Module designs 1 and 2 made with conventional front ju

cells, Al frames, and polymeric backsheets were selecte

• Module 1

– 230 W class mc-Si module design (60 15.6 cm x 15.6 cm cell)– Manufactured from 2011 onward– Based on previously published reports of PID tests under diffe

module was expected to show a small PID signal with some scbut generally less that 5% degradation

• Module 2

– a 170 W class mc-Si module design (72 12.5 cm x 12.5 cm ce– Manufactured in 2008 or 2009– Expected to show PID based on data obtained at NREL under 

conditions, but significant scatter in the data was expected due control and increased variability in the cells made during this pevidenced in prior EL imaging.

• Module 3, in test
Pass/fail condition: If 1 or 2 modules tested in a polarity fail (Pmthat design is considered failed in that polarity at the given test 

Module design 1 failed in the (-) polarity test at one of the five labs when one of the two replicas tested there failed. 

Overview of pass/fail results of two different module de

labs

(stress polarity)

Module design 2 fapolarity test at all fleast one of the twfailed at each lab.
Considering stress in (-) bias, module design 1 show

mean degradation and standard deviation of degradati

Data point yielding failure of design

1

in (‐) bias at lab #5

(stress polarity)
Results are controlled by module design

no conclusive proof that results are controlled 

(stress polarity)
Module degradaviewed as a funcdetermine if any than others. The analysis sholab is the least inthe variation, the next important famodules within a (residual) is the 

What extent did the possible varying severit

of the test labs influence outcomes?
Examination of lab to lab variability

Subtracting median degradation for each module type also fa

statistically significant difference between labs
0123456

0 

I (A)

Results of a module design 2 from lab 4

EL: M0903‐0007, pre EL: M0903‐0007, post EL: M0903‐0014, pre EL: M0914‐0

M0

Potential‐induced degradation in the most degraded

module design
Conclusions

• 2 module designs completed testing at 5 labs for sy

voltage durability

• The test was able to statistically significantly disce

module designs for potential-induced degradation

• Extent of variability measured for each module des

line with expectations based on previous experienc

• Potential-induced degradation was observed in the 

electroluminescence

• lab to lab variability was the least influential variabl• The test (per IEC 62804 draft) appears successful w

to the scope of this round robin with results of two modules analyzed

This work was supported by the U.S.

Department of Energy under Contract No. DE‐

AC36‐08‐GO28308 with the National

Renewable Energy Laboratory