PHOTON Laboratory PHOTON Laboratory GmbH Juelicher Strasse 376 52070 Aachen | Germany Phone 00 49 / 241 / 40 03 – 53 00 Fax 00 49 / 241 / 40 03 – 57 00 www.photon.info/laboratory Ms. Vivian Zhao [email protected] Phone 00 49 / 241 / 40 03 – 106 Mr. Qingke Xiang [email protected] Phone 00 49 / 241 / 40 03 – 52 19 Contacts Guido Schiefer / photon-pictures.com PID free? Potential Induced Degradation Test (PID) at least -1,000 V at 25° C for the duration of 168 hours. This arrangement simulates a module’s active life of a few years in only seven days. The initial measurement, including a performance measurement as well as electroluminescence imaging, is repeated after the treatment to check the module’s performance and quality. If the module’s maximum power output has significantly reduced after the test, we conclude that the te- sted module is not PID resistant. 2/ Measurement under wet conditions High humidity considerably aggravates a module’s vulnerability to PID. In addition to the test described in option 1, modules may also be tested under wet conditions. In order to ensure exact comparability, the module’s front is completely bathed in water at PHOTON’s laboratory. The module is exposed to a negative potential of 1,000 V for the duration of 168 hours. Similar to option 1, a performance measurement at STC and electroluminescence imaging after the test allow conclusions to be drawn on the module’s PID resistance. Frank Schuberth / photon-pictures.com P ID is short for Potential Induced Degradation. The phenomenon has been known to scientists for years, but it has not been studied to the last detail. The causes can be described as follows: In PV installations with high operating voltages (up to 1,500 Volts), ne- gative charges may flow through the encapsulating material and the frame as stray current, and cause an accumulation of positive charges at the cell’s surface. High temperatures and humidity further amplify the effect. Despite all research efforts by manufacturers, a significant portion of modules is still vulnerable to PID. In the course of a few years (or months, in some cases), they cause significant power losses. The worst part is that performance measurements and electrolumine- scence tests of these modules before their installation do not show any irregularities. The effect is reversible. The consequences of PID can be devastating. Our numerous tests have discovered modules whose power output shrank by more than 80 percent. Our test options 1/ Measurement under dry conditions As the PID phenomenon only occurs when there is high negative po- tential between the cells of a module and its frame (ground potential), the module’s glass surface is covered with aluminum foil and exposed to Electroluminescence image before PID testing Electroluminescence image after PID testing photon-pictures.com (2)
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PHOTON Laboratory
PHOTON Laboratory GmbHJuelicher Strasse 376
52070 Aachen | Germany
Phone 00 49 / 241 / 40 03 53 00Fax 00 49 / 241 / 40 03 57 00
www.photon.info/laboratory
Ms. Vivian [email protected] 00 49 / 241 / 40 03 106
Mr. Qingke Xiang [email protected] Phone 00 49 / 241 / 40 03 52 19
Contacts
Guid
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Guid
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phot
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Guid
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phot
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res.
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Guid
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phot
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ictu
res.
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Guid
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phot
on-p
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res.
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Guid
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er /
phot
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PID free?Potential Induced Degradation Test (PID)
at least -1,000 V at 25 C for the duration of 168 hours. This arrangement simulates a modules active life of a few years in only seven days. The initial measurement, including a performance measurement as well as electroluminescence imaging, is repeated after the treatment to check the modules performance and quality. If the modules maximum power output has signifi cantly reduced after the test, we conclude that the te-sted module is not PID resistant.
2/ Measurement under wet conditions High humidity considerably aggravates a modules vulnerability to
PID. In addition to the test described in option 1, modules may also be tested under wet conditions. In order to ensure exact comparability, the modules front is completely bathed in water at PHOTONs laboratory. The module is exposed to a negative potential of 1,000 V for the duration of 168 hours. Similar to option 1, a performance measurement at STC and electroluminescence imaging after the test allow conclusions to be drawn on the modules PID resistance.Fran
k Sc
hube
rth /
phot
on-p
ictu
res.
com
PID is short for Potential Induced Degradation. The phenomenon has been known to scientists for years, but it has not been studied to the last detail. The causes can be described as follows:
In PV installations with high operating voltages (up to 1,500 Volts), ne-gative charges may fl ow through the encapsulating material and the frame as stray current, and cause an accumulation of positive charges at the cells surface. High temperatures and humidity further amplify the effect.
Despite all research efforts by manufacturers, a signifi cant portion of modules is still vulnerable to PID. In the course of a few years (or months, in some cases), they cause signifi cant power losses.
The worst part is that performance measurements and electrolumine-scence tests of these modules before their installation do not show any irregularities. The effect is reversible.
The consequences of PID can be devastating. Our numerous tests have discovered modules whose power output shrank by more than 80 percent.
Our test options
1/ Measurement under dry conditions As the PID phenomenon only occurs when there is high negative po-
tential between the cells of a module and its frame (ground potential), the modules glass surface is covered with aluminum foil and exposed to
Electroluminescence image before PID testing
Electroluminescence image after PID testing
phot
on-p
ictu
res.
com
(2)
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