光伏組件戶外老化經(jīng)典論文 - 圖文-

1、Comparison of outdoor weathering and accelerated laboratory testing of PV modules ATLAS® Technical Conference on Accelerated Ageing and Evaluation (ATCAE 7-8 December 2011 Berlin, Germany Dr. Werner Herrmann TÜV Rheinland Energie und Umwelt GmbH D-51101 Köln Phone: +49-221/806-2272 Em

2、ail: werner.herrmann TÜV Rheinland Group PV Activities Global PV network with 6 Solar Energy Assessment Centres in Cologne (Germany, Tempe (Arizona, Shanghai (China, Taipei (Taiwan, Yokohama (Japan, Bangalore (India and more than 200 PV experts Team of 65 engineers and technicians in Cologne (&

3、gt;25 years work experience in PV Experience PV module qualification testing: - Crystalline silicon PV modules: since 1995 - Thin-film PV modules: since 1999 - Concentration PV modules: since 2008 Quality assurance for PV power plants Applied research on PV module and PV systems aspects Member of st

4、andardization working groups (IEC, CENELEC, IECEE, DKE, SEMI, ANSI, ASTM 2 10.11.2011 ATCAE, Berlin, 7/8 December 2011 Outline Introduction IEC qualification testing / Accelerated laboratory testing Laboratory testing - Extended Thermal Cycling Test - Extended Damp Heat Test Outdoor weathering in va

5、rious climates Conclusions Reference: W. Herrmann et al.: Outdoor weathering of PV modules - Effects of various climates and comparison with accelerated laboratory testing, 37 IEEE PVSC, 2011 3 10.11.2011 ATCAE, Berlin, 7/8 December 2011 Introduction Reliable operation of PV modules PV modules are c

6、omplex products that combine materials of different physical and chemical properties. During their lifetime they have to withstand a number of environmental impacts. Irradiance: sun, sky Temperature: heat, frost, night-day cycles Mechanical stress: wind-,snow load hail impacts Atmosphere: Salt mist,

7、 dust, sand, pollution Humidity Moisture: rain, dew, frost 4 10.11.2011 ATCAE, Berlin, 7/8 December 2011 Introduction Reliability testing For product qualification of PV modules commonly IEC test standard are referred. The stress tests defined in the test programmes are short-duration accelerated te

8、sts that are performed at stress levels higher than use stress in order to facilitate failures in a timely manner. The qualification tests can be considered as a minimum requirement to undertake reliability testing. The primary goal of IEC qualification testing is to identify the initial short-term

9、reliability issues in the field. This means that mainly early product failures are detected. In order to reveal weaknesses in the construction so-called extended IEC qualification testing is typically applied. Failure Rate IEC 61215: c-Si PV modules IEC 61646: Thin-film PV modules IEC 62108: CPV mod

10、ules Early failures Random failures Degradation Wear-out failures Time of Operation Open the box failure 5 10.11.2011 ATCAE, Berlin, 7/8 December 2011 Introduction German PV module reliability research project Cooperation partners: Fraunhofer-ISE (coordinator, TÜV Rheinland, Fraunhofer-IWM, Hum

11、boldt-University Berlin, 5 PV module manufacturers Objectives for PV module research: Demonstration of degradation mechanisms in the test laboratory induced by thermo-mechanical stresses (thermal cycling test and moisture ingress into the encapsulation (damp heat test Demonstration of real load prof

12、iles for PV module exposure in different climates (open-rack mounting Understanding of degradation mechanisms occurring during long-term operation of PV modules in various climates Provision of experimental data for finding correlations between laboratory testing and outdoor weathering Provision of

13、experimental data for development of realistic and effective procedures for accelerated testing, which can simulate 25 years of operation 6 10.11.2011 ATCAE, Berlin, 7/8 December 2011 IEC Qualification Testing Performance qualification acc. to IEC 61215 (c-Si PV modules Preconditioning (5 kWh/m²

14、; Initial measurements: Visual inspection, electrical performance, insulation, wet leakage current Electrical parameters Outdoor exposure Bypass diode Hot-Spot UV preconditioning Temperature cycling (50 Humidity freeze Damp heat Temperature cycling (200 Electrical terminations Mech. load Hail Final

15、measurements: Visual inspection, electrical performance, insulation, wet leakage current 7 10.11.2011 ATCAE, Berlin, 7/8 December 2011 IEC Qualification Testing Environmental stress tests Thermal Cycling This test is primarily a mechanical fatigue test where differential thermal expansion may cause

16、cells or interconnects to crack. This test can also address any thermal mismatch between components. (Test conditions: 200 temperature cycles between -40°C and +85°C, cycle time: 2.8 to 6 hours Current injection: T>25°C, module is operated in forward biased condition, test current

17、equivalent to rated Isc 8 10.11.2011 ATCAE, Berlin, 7/8 December 2011 IEC Qualification Testing Environmental stress tests Damp Heat This severe environmental conditioning accelerates material corrosion and often results in noticeable discoloration or voids of the encapsulation material and suitabil

18、ity of polymeric materials and adhesives. (Test conditions: 85°C/85% RH, 1000 hours Humidity Freeze (HF This test combines the elements of the damp heat test with the elements of the thermal cycling test. This test often results in noticeable changes in encapsulation materials as well as corros

19、ion. In particular, the HF test identifies issues with adhesives. (Test conditions: -40°C and +85°C/85% RH, 10 cycles, 24 hours each UV Exposure This test is a preconditioning test for other environmental stress tests. Because of low UV dosage it does not really address photo-oxidation for

20、 polymeric materials. (Test conditions: 60°C, UV dosage 15 kWh/m², UV irradiance max. 5 times related to AM1.5 reference 9 10.11.2011 ATCAE, Berlin, 7/8 December 2011 IEC Qualification Testing Monitoring of degradation Degradation parameter Visual changes (Yellowing, soiling, corrosion etc

21、. Deterioration of max. power Insulation resistance Internal series resistance Microcracks in cells, interruptions of electrical interconnection circuit Test method / procedure Visual inspection Max. power characterisation at STC (5% threshold in IEC 61215 Dry insulation test Wet insulation test I-V

22、 measurement at 3 irradiances and constant module temperature Electroluminescence (EL record ITEST = ISC,STC 10 10.11.2011 ATCAE, Berlin, 7/8 December 2011 IEC Qualification Testing Failure rates c-Si PV modules (2005 2010 Failure rates in IEC 61215/ IEC61730 qualification testing at Solar Energy As

23、sessment Centre (SEAC of TÜV Rheinland in Cologne 1,1% 1,1% 0,8% 0,7% 0,5% 1,1% 0,1% 1,2% 13,8% 2,9% 3,0% 3,0% 3,4% Initial measurement Damp-heat test Thermal cycling test (200 Mechanical load test Humidity-freeze test Hot-spot endurance test Thermal cycling test (50 Bypass diode thermal test F

24、rame Total no. tested modules: 12.233 10% failure rate related to stress tests 28 % failure rate related to module type initial 7,3% 18,8% DH HF 10,4% Scratch test Robustness of terminations Impulse voltage test Hail test Insulation test Reverse current Outdoor exposure test Module breakage test UV

25、preconditioning test ML TC200 12,6% 18,1% 11 10.11.2011 ATCAE, Berlin, 7/8 December 2011 Laboratory Testing Failure mechanism: Thermo-mechanical induced stress PV modules combine materials with different coefficients of thermal expansion (glass cover, polymeric encapsulation, solar cells, polymeric

26、backsheet, metal parts of internal wiring Degradation processes may occur originating from thermo-mechanically induced stresses to interconnects (Cyclic movement of cells of loss of adhesion strength at interfaces 1 Glass cover Solar cell Backsheet Typical layout of a crystalline silicon PV module 1

27、 S. Dietrich: Mechanical and Thermo-Mechanical Assessment of Encapsulated Solar Cells by Finite-Element-Simulation, SPIE Optics+Photonics, 2010 Cell interconnect / copper ribbon coated with solder Encapsulant 12 10.11.2011 ATCAE, Berlin, 7/8 December 2011 Laboratory Testing Extended Thermal Cycling

28、test Extended temperature cycling test with 7 crystalline silicon PV modules with intermittent diagnostic measurements after 200, 400, 600 and 800 cycles. 10% Pmax change related to initial power Results: All modules fulfill IEC 61215 test requirements (TC200 M1 M2 M3 M4 M5 M6 M7 0% -10% -20% -30% T

29、hree modules still fulfill IEC 61215 test requirements after TC800 Increased power degradation starting from TC400 TC200 IEC Test level -40% -50% Initial TC400 TC600 TC800 13 10.11.2011 ATCAE, Berlin, 7/8 December 2011 Laboratory Testing Extended Thermal Cycling test Electroluminescence analysis: Va

30、riations in brightness across the cell area indicates inhomogeneous current flows between bus bars Ö Total or incomplete crack of cell connectors Loose contact Change of contact resistance TC200 14 10.11.2011 ATCAE, Berlin, 7/8 December 2011 TC400 TC600 Laboratory Testing Extended Thermal Cycli

31、ng test IR analysis: Breakage of one cell connector and incomplete disconnection of second connector will cause local heating Ö Potential risk of backsheet damage and loss of insulating properties 15 10.11.2011 ATCAE, Berlin, 7/8 December 2011 Laboratory Testing Summary of Thermal Cycling test

32、Breakage of cell connectors is the dominating degradation mechanism for thermal cycling tests of c-Si modules in the test lab. EL analysis is appropriate diagnostic method for identification of cracks in internal wiring, but may not find all failures in the interconnection circuit (loose contacts. Cracks are potential locations for heating if all interconnects of a cell are affected by material fatigue. Standard TC200 test does no