Reliability of PV-modules

Transcription

1 1 SPIE Conference Reliability of PV-modules Natural, accelerated and simulated degradation Projects PV-Zuverlässigkeit and Performance SP5 Michael Köhl Fraunhofer ISE, Freiburg, Germany PV-Zuverlässigkeit Project partners: Fraunhofer ISE, Freiburg, DE TÜV Rheinland, Cologne, DE funded by BMU/PTJ and industry Industry involvement: Schott Solar, DE Scheuten Solar, DE Solon, DE Solarwatt, DE Solarworld, DE Focus: Crystalline Silicon based modules Encapsulating components Duration: 1/25 12/28 Folie 2

2 2 Develop ageing models based on `real life stress factors Develop new accelerated ageing procedures Facilitate innovation in module technology Provide manufacturers with service life data for setting their guarantee specifications Increase planning reliability for investors Focus: Thin Film based modules Encapsulating components Duration: 1/26 12/29 Project partners: Industry involvement: Fraunhofer ISE, Freiburg, DE Joint Research Centre, Ispra, IT TÜV, Cologne, DE ECN, Petten, NL ZSW, Stuttgart, DE CREST, Loughborough University, UK EPIA, Brussels, BE GENEC, Cadarache, FR SP, Boras, S PCCL, Leoben, AT Meteoconsult, München, DE Schott-Solar, Alzenau, DE Schott Solar, DE Evonik, DE Juraplast, DE Flexcell, CH Würth, DE Sharp, J/DE Avancis, DE Unisolar, USA/DE First Solar, USA/DE

3 3 SP 1 WP1 Failure and Risk Analysis, sample selection SP 2 WP2 Outdoor testing, load monitoring Modelling: WP3 -Accelerated Materials -outdoor Modules WP5 Accelerated indoor testing PV- modules WP4 Accelerated indoor testing materials SP 4 WP 7 Development of life-tests for modules WP 6 Development of life-tests for materials SP 4 SP 8 SP 8 WP8 LCA Aspects SP 6 Candidate materials identified in WP 5:1 Name Composition Trade name Manufacturer encapsulant EVA ultra fast cure ethylene vinyl acetate Vistasolar Etimex (D) TPSE thermoplastic silicon elastomer Geniomer Wacker (D) Ionomer 1 ionised ethylene acrylic acid copolymer Jurasol Juraplast (D) Ionomer 2 ionised ethylene acrylic acid copolymer Jurasol Juraplast (D) Europlex glazing/backsheet coextruded PMMA-PVDF film polymethylmethacrylate (PMMA) polyvinylidenfluoride (PVDF) backsheet Clear HC 9971 Degussa (D) TPT PVF-PET-PVF multilayer film Icosolar Isovolta AG (AUT) polyethylene terephthalate (PET) polyvinylfluoride (PVF) Polyester PET-PE multilayer film Toyalsolar Toyo Aluminium KK (J) polyethylene terephthalate (PET) polyethylene (PE)

4 4 Europlex-PMMA Elongation at Break [%] WoM, 65 C, 6% RH WoM, 85 C, 26% RH Expon. (WoM, 65 C, 6% RH) Expon. (WoM, 85 C, 26% RH) Time [hrs] Ionomer 1 WoM: 65 C, 6% RH, Front Back.4.4 Absorbance hrs 2 hrs 3 hrs 4 hrs 5 hrs Absorbance hrs 2 hrs 3 hrs 4 hrs 5 hrs Time [hrs] Wavenumber [cm -1 ]

5 5 1 8 UV-VIS-NIR: Ionomer 1 WoM: 65 C, 6% RH Transmittance [%] Wavelength[nm] PET, Photo-oxidation Indexes 4 3 PI-index 2 1 WoM, 65 C, 6% RH WoM, 85 C, 26% RH WoM, 65 C, 6 RH WoM, 85 C, 26% RH Time [hrs]

6 6 Development of degradation indicators at Humboldt Universität zu Berlin a 3,5 b 3,5 Luminescence intensity, a.u. 3, 2,5 2, 1,5 1,,5 Ageing (in hours) Luminescence intensity, a.u. 3, 2,5 2, 1,5 1,,5 Ageing (in hours) , Wavelength, nm, Wavelength, nm Fluorescence of samples containing EVA-UFC as polymer with TPT back foil at different ageing times. (a) Aging with DH 85/85 (b) Aging with UV /85 C. Folie 11 Modelling: 1. Modules: IV-curves, efficiency (irradiation, temperature) 2. Materials degradation, energy and mass transport in modules, worst case climates 3. Module degradation, worst case climates, extreme climates 4. Energy yield (life-time), for any climate of operation

7 7 The change ΔP in a property P : UV-dose ΔP( t = t exp( E A aq c aq i ) = r ph P / RT( t = t exp( E Δt( t aq = t ) = A i i )) Δt( t / RT( t = t i ph i I UV = t ) + ( t = t )) Δt( t = t i ) i ) and the total change from t i = to t i =t n: i n P ( t = t ) = ΔP( t t ) n = i= n = i= Folie 13 i Module characterisation measured by JRC and labeled Cell a-si CdTe CIS a-si CIS c-si µc-si /a-si a-si Product Schott ASI F1 Exp. First Solar FS-27 AVANCIS Shell Unisolar ES-62T Würth WSG36E8 Schott Reference ASE-165 Sharp Solar NA-91WQ Flexcell Sunslick 7 Watts Pmpp /W 12, ,75

8 8 I_korr_aug[A] I_korr_sep[A] 1,4 1,2 1, I_korr[A],8,6,4,2, U_raw[V] Outdoor exposure in Freiburg, Germany and Cadarache, France 2,5 Lineares Fitten von Unisol16_B9 UniSol Pyranometer 2, 1,5 Imp /A 1,,5, Irradiance /W

9 9,14,12,1 Würth Flaechenwirkungsgrad Avancis23 Flaechenwirkungsgrad SchoAsi15 Flaechenwirkungsgrad FirstSol16 Flaechenwirkungsgrad Flexcel31 Flaechenwirkungsgrad Referenz Flaechenwirkungsgrad Sharp Flaechenwirkungsgrad UniSol Flaechenwirkungsgrad efficiency,8,6,4,2, time /h P max= f(irradiance)

10 1 Modelling: 1. Modules: IV-curves, efficiency (irradiation, temperature) 2. Materials degradation, energy and mass transport in modules, worst case climates 3. Module degradation, worst case climates, extreme climates 4. Energy yield (life-time), for any climate of operation Folie 19 Outdoor monitoring of climatic loads: Radiation (UV, solar) Humidity Temperature (ambient and sample) Wind and mechanical loads of innovative PV-modules and new materials: Impact of extreme, but natural loads Identification of week points Validation of accelerated indoor tests Folie 2

11 11 City Cologne Germany Dessert Sede Boqer Israel Alpes Zugspitze Germany Tropics Serpang Indonesia Folie 21 Alpine mounting Folie 22

12 12 Module degradation Crystalline Silicon based modules from each industrial partner 3 exposed at the 4 test sites after initial characterisation according to IEC The first was brougt to the lab for re-measurement after 1 year Identical modules are in accelerated testing now Experimental samples were made with new encapsulation/back-sheet combinations Folie 23 Module degradation Detoriation of test modules after 12 months at the alpine test site Folie 24

13 13 Module degradation Corrosion of cell connectors after 24 months in Arizona Degradation of the encapsulant after 12 months at the tropical test site Folie 25 Modelling: 1. Modules: IV-curves, efficiency (irradiation, temperature) 2. Materials degradation, energy and mass transport in modules, worst case climates 3. Module degradation, worst case climates, extreme climates 4. Energy yield (life-time), for any climate of operation Folie 26

14 14 Modeling Deterministic model for aging processes Changes of the degradation indicator P i after the testing time Δt i is for p degradation processes: For constant load: ΔP i = Σ p (A p I n Δt i exp[-e p /RT] exp [C p *rf]) For dynamic load: ΔP j = Σ j i=1 {Σ p (A p I in Δt i exp[-e p /RT i ]exp [C p *rf i ])} Degradation process parameters Folie 27 Temperature Ambient Tamb temperature Average Tavg module temperature 12 Tropics 12 frequency [h] Desert City Alpes frequency [h] temperature [ C] temperature [ C] Folie 28

15 15 Temperature exp[-e p /RT eff ] = 1/(t max -t min ) Σ tmax tmin exp[-e p /RT(t)]Δt 6 Effective Mean Temperature, Constant test temperature that Corresponds to the natural load in the same period effective mean temperature [ C] Tropics Desert City Alpes Depends on the activation energy of the degradation process activation energy [kj/mol] Folie 29 Radiation Accumulated dose of UVand solar radiation for one year dose [kwh/m²] 25 Global Tropics Desert City Alpes 25 UV Snow on the sensors exposure time starting at Jan 1 [days] Folie 3

16 16 UV-radiation 6 UV-dose during one year Has to be corrected for calibration errors total UV dose per temp.-interval [Wh/m²] Tropics Desert City Alpes mean module temperature [ C] Folie 31 Humidity 2 Tamb if RH>=6% 2 Tavg if RH>=6% Tropics Desert frequency [h] frequency [h] City Alpes Ambient temperature [ C] temperature [ C] Folie 32

17 17 Humidity Actual Damp-Heat-Test Would be appropriate for the alpine location and a rate dominating degradation process with an activation energy of 5 kj/mol Tropical climate requires 1 times more equivalent testing time at 85 C [h] based on Tavg when RH>=6% Tropics indo isra Desert koel schn City Alpes t R = 25*876 exp (- E T R ( T 1 eff - T 1 1 R )) activation energy [kj/mol] Folie 33 Humidity Humidity above 8% (TOW = time of wetness) For one year Tavg if RH>=8% Tropics Desert City frequency [h] Tamb if RH>=8% frequency [h] Alpes Ambient temperature [ C] Average module temperature [ C] Folie 34

18 18 Humidity -ln(permeation) 6, 5,8 5,6 5,4 5,2 5, 4,8 4,6 4,4 4,2 4,,3 TPT-Back-sheet,35 -ln(permeation) Linear Fit of Data1_D 23 C 38 C Aktivierungsenergie E= 41,5 kj/mol 55 C 1/T,31,315,32,325,33,335,34 Water vapour diffusion in encapsulant equivalent testing time at 85 C [h] based on Tavg when RH>=8% 25 a Tropics for EVA: 1,5a DH Tropics 1 2 Desert 3 4 City Alpes Standard Damp-Heat-Test activation energy [kj/mol] Testing times for 25 years service life for the different locations Folie 35 Simulation Damp-Heat 3 mm,5 mm BS EVA Si EVA Glas 1 h Folie 36

19 19 2 h 3 h Folie 37 Small changes of the electrical properties to be detected Folie 38

20 2 Power measurements and lightsoaking of Thin Film Modules Normalized values (%) 12 Flexcell a-si module Percent calculated with the value at 12 hours Isc Voc Pmpp G.pyrano FF Eta.pyrano Time (hours) Folie 39 Task 5.5.2: Screening testing Test conditions / test programme Institute T ( C) Rh (%) UV*(- ) modules Start measuring Exposure time (h) JRC x 8 May 25, 1, 2, 4 SP x 8 October 1, 2, 4 SP x 8 October 1, 2, 4 ISE 65 85? 2 x 8 April 9 25, 1, 2, 4 ISE 85 5? 2 x 8 Februar 9 25, 5, 1, 2, 4 ZSW V 1 x 8 November 25, 5, 1, 2, 4 TÜV 85 high 5 2 x 8 January 9 1, 25, 5, 1, 2 TÜV 85 low 5 2 x 8 January 9 1, 25, 5, 1, 2 Folie 4

21 21 Indoor testing UV-radiation distance in cm distance in cm Folie 41 W/m² 174,8 176,8 178,8 18,8 182,8 184,8 186,8 188,8 19,8 192,8 194,8 196,8 198,8 2,8 22,8 24,8 26,8 28,8 21,8 212,8 214,8 216,8 218,8 22,8 222,8 224,8 226,8 228,8 23,8 232,8 234,8 236,8 237, Outlook indoor testing Powerful UV-light source to be developed 2, 1,75 1,5 Combination UV damp-heat for entire modules rel. units 1,25 1,,75,5,25, wavelength /nm Folie 42

22 22 Outlook Evaluation of outdoor exposure Indoor testing Comparison accelerated indoor testing outdoor testing Modelling service life Service life test procedure Folie 43