PV MODULE RELIABILITY AND QUALITY TESTING

Transcription

1 PV MODULE RELIABILITY AND QUALITY TESTING TestLab PV Modules Daniel Philipp Fraunhofer Institute for Solar Energy Systems ISE PV Investors Day

2 AGENDA n Introduction n Technological risk factors and failure experience n Strengths and weaknesses of established quality standards n Testing methods n Electroluminescence imaging n Cell breakage due to thermo-mechanical stress n Potential induced degradation (PID) n Summary 2

3 Fraunhofer ISE Fields of Activity Fotos n Solar Thermal Technology n Energy Efficient Buildings n Hydrogen Technology n Energy System Technology n Photovoltaics 3

4 TestLab PV Modules Failure Research and Testing Service n Failure analyses n Identification of root causes and relevant stress factors n Failure prevention Accredited Testing Laboratory for: - IEC IEC /2 4 - IEC 61646

5 Technical Risks with focus on module reliability Risk factors! Market pressure PV industry à Innovations to save costs / increase efficiency à Might lead to save QA / QC effort! More challenging installation climates (desert, tropical) Learning effects from increasing long term experience with PV application Improved Testing methods à Type testing acc. to standards à Qualtty control measures 5

6 Experience on Serial Failures Serial Failures Company Year Severety Potential Induced Degradation 1 Sunpower 2006 Medium Potential Induced Degradation 2 Multiple today Overheating due to cell cracks Multiple today Medium Critical Strong back-sheet browning Multiple 2008 Medium Delamination Shell Solar 2013 Critical Overheating due to interconnction corrosion BP-Solar 2009 Critical J-box overheating Multiple 2010-today Critical Light induced degradation on PERC cells Multiple

7 Experience on Serial Failures Serial Failures Company Year Severety Potential Induced Degradation 1 Sunpower 2006 Medium Potential Induced Degradation 2 Multiple today Overheating due to cell cracks Multiple today Medium Critical Strong back-sheet browning Multiple 2008 Medium Delamination Shell Solar 2013 Critical Overheating due to interconnction corrosion BP-Solar 2009 Critical J-box overheating Multiple 2010-today Critical Light induced degradation on PERC cells Multiple

8 Module Testing Strengths and weaknesses of standards n IEC n IEC n IEC /2 à c-si PV Modules à Thinfilm modules à Safety standard for PV modules 8

9 Certification acc. to IEC Full Testings Scope PreCond (LID) - Visual Inspection - Power - Insulation - Leakage Current TC, NOCT, low irrad. UV (15 kwh/m²) Temp.-Cycling 200 cycles Outdoor Exposure Temp.-Cycling 50 Damp Heat Bypass Diode Humidity Freeze Mech. Load Hail Hot Spot Termination Visual Inspection - Power - Insulation - Leakage Current 9

10 Certification acc. to IEC Statistical Failure Rates During Certification Failure Rate per Test in % HF HS ML DH TC200 TC50 OE HL UV About 30 % of all module types fail in at least one test Stress Test (HF): Humidity Freeze, (HS): Hot Spot, (ML): Mechanical Load, (DH): Damp Heat, (TC200/50): Thermal Cycling, (OE): Outdoor Exposure, (HL): Hail Test, (UV): UV Test 10

11 Certification acc. to IEC and IEC Strength and Weaknesses Strengths: n The only binding testing schemes which assure minimum quality and safety requirements n Independency n Consistency of materials and components covered Weaknesses n Test done once on few modules n Important degradation factors not sufficiently covered: n High ground potential (PID) n UV irradiation n Combined appearance of stress factors 11

12 Module Testing Electroluminescence imaging n Manufacturers: In-line quality control n Testing Labs: To evaluate test results n Buyers: Set acceptance criteria micro cracks inactive cell areas grid finger interruptions 12

13 Module Testing Electroluminescence imaging n Manufacturers: In-line quality control n Testing Labs: To evaluate test results n Buyers: Set acceptance criteria micro cracks Example: max 3 cells / module max 5 cracks in total inactive cell areas Example: max 1 cell / module max 15 % cell area grid finger interruptions Example: max 3 cells / module 13

14 Module Testing Thermal Cycling Test from IEC Cycles -40 ß à 85 Celsius Pass criterion from certification: max. 5 % power reduction No visible defects Electrical insulation OK 14

15 Module Testing Thermal Cycling Test from IEC Before Thermal Cycling 200 After PASS! 15

16 Module Testing Thermal Cycling Test Statistics: Cell-crack formation and power after Thermal Cycling Additional cracks rel. power loss rel. frequency [%] additional micro cracks after 200 cycles after 400 cycles More than 50 % of modules have less than 3 additional cell cracks! rel. frequency [%] after 200 cycles of thermal cycling after 400 cycles of thermal cycling IEC- fail-level rel. power loss [%] 16

17 Module Testing Thermal Cycling Test from IEC Before Thermal Cycling 200 After PASS! 17

18 Module Testing Potential Induced Degradation + inverter PVstring - 18 PID: System Potential to grid ground leads to power degradation on susceptive Neg. ground potential c-si PV modules

19 Module Testing Potential Induced Degradation PID Laboratory Test 0% PID Test -83,3 % n Draft for standardised test procedure: n Volts cell to frame n Climate chamber: n 60 Celsius n 85 % relative humidity Module is rated PID sensitive if powerloss < 5% Number of tested modules % - 80 % - 60 % - 40 % - 20 % 0 % Relative Power Loss due to PID Indoor Test 19

20 Summary n Please learn from experiance on failures! n Testing methodogies have improved n International standards ensure basic quality n Tests beyond standards recomended n For better type design tests n To contol quality 20

21 Thank-you for your attention! Fraunhofer Institute for Solar Energy Systems ISE Daniel Philipp 21

22 Module Testing Electroluminescence imaging n EL inspection became state of the art as inline- measurement: (before / after lamination) n Buyers of modules define acceptance criterions micro cracks Example: max 3 cells / module max 5 cracks in total inactive cell areas Example: max 1 cell / module max 15 % cell area grid finger interruptions Example: max 3 cells / module 22