Abstract
Acceleration factors are calculated for crystalline silicon PV modules under system voltage stress by comparing the module power during degradation outdoors to that in accelerated testing at three temperatures and 85% relative humidity. A lognormal analysis is applied to the accelerated lifetime test data considering failure at 80% of the initial module power. Activation energy of 0.73 eV for the rate of failure is determined, and the probability of module failure at an arbitrary temperature is predicted. To obtain statistical data for multiple modules over the course of degradation in-situ of the test chamber, dark I-V measurements are obtained and transformed using superposition, which is found well suited for rapid and quantitative evaluation of potential-induced degradation. It is determined that shunt resistance measurements alone do not represent the extent of power degradation. This is explained with a two-diode model analysis that shows an increasing second diode recombination current and ideality factor as the degradation in module power progresses. Failure modes of the modules stressed outdoors are examined and compared to those stressed in accelerated tests.
Original language | American English |
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Pages | 1750-1755 |
Number of pages | 6 |
DOIs | |
State | Published - 2012 |
Event | 38th IEEE Photovoltaic Specialists Conference, PVSC 2012 - Austin, TX, United States Duration: 3 Jun 2012 → 8 Jun 2012 |
Conference
Conference | 38th IEEE Photovoltaic Specialists Conference, PVSC 2012 |
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Country/Territory | United States |
City | Austin, TX |
Period | 3/06/12 → 8/06/12 |
Bibliographical note
See CP-5200-54109 for preprintNREL Publication Number
- NREL/CP-5200-56918
Keywords
- Current-voltage characteristics
- Degradation
- High-voltage techniques
- Photovoltaic cells
- Photovoltaic systems
- Reliability