Excellent MWT Module Performance and Durability Using Silicone Electrically Conductive Adhesive

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1 Excellent MWT Module Performance and Durability Using Silicone Electrically Conductive Adhesive Yanghai Yu, Guy Beaucarne, Jason Wei, Brian Chislea,Adriana Zambova Dow Corning Kees Broek, Ian Bennett ECN Hongfeng Lin, Zhe Qiu, Kaiyin Cao, Liyan Zhao, Xianzhi Chen, Wei Long Tianwei Jan Bakker, Nico van Ommen, Egbert Fredrikze Eurotron MWT Workshop, Shanghai, May 19, 2014

2 Outline Introduction Dow Corning PV-5802 Electrically Conductive Adhesive Mini-module results Module aging analysis Full size module results Conclusion

3 Introduction to Dow Corning Dow Corning was established in 1943 specifically to explore and develop the potential of the silicon atom. Today: $6.12 billion USD in sales 7,000 products and services; 5,388 active patents 25,000 customers; 11,000 employees 4-5% investment of sales in R&D 45 manufacturing and warehouse locations 17 Science and Technology Centers One major S&T center located in Shanghai

4 MWT module structure Aluminium frame Silicone sealant Glass Front EVA Punched back EVA MWT Cell Backsheet Copper foil Electrically Conductive Adhesive

5 Dow Corning PV-5802 : New silicone ECA for back-contact modules PV-5802 : Result of 4 years of specific development for PV, building on Dow Corning s long expertise in adhesives for electronics One part material Thixotropic properties for stencil printing Proved production run Cure profile matched to lamination cycle Flexible, low modulus Designed to be compatible with Organic Solderability Preservative (OSP)-finished CBS Low contact resistance on OSP-finished CBS 1.E+10 1.E+09 Shear storage modulus G (Pa) 1.E+08 Organic ECA A Organic ECA B PV-5802 (<< 0.5 mohm cm 2 ) 1.E Temperature ( C)

6 Mini-module results 4 cells mini-mwt modules made at ECN using conductive backsheet with OSP finish and without any other isolation material than EVA 156 mm multi-mwt cells ECA used was PV-5802 Cell-to-module losses Cell-to-module efficiency loss is low thanks to MWT structure and low contact resistance ECA

7 Relative power (%) Relative power (%) Relative power (%) Relative power (%) Mini-modules with silicone ECA very stable in extended aging tests IEC criteria: <5% power loss in TC200 and DH % 105% 105% 105% M1 100% 100% 100% 100% M2 M3 95% IEC requirement M5 95% 95% 95% IEC requirement IEC IEC requirement M4 90% M6 M7 90% 90% 90% 85% M Number of thermal cycles 85% 85% 85% Hours in damp Hours Hours heat in damp in damp heat heat Rel. efficiency of 4 cell modules after a TC (-40/+85ºC) test 3 x IEC requirement for thermal cycling and still going strong! Rel.efficiency of 4 cell modules after DH(85 %RH/85 ºC) test 2 x IEC requirement in damp heat

8 Failure after 2500 hours damp heat is not likely due to the ECA Discoloring of the white polymer back sheet in contact with EVA after DH2500 Strong discoloring of the copper part next to the polymer parts EL images also showed the failed area limited on the edge Possible influence of moisture penetration through isolation tracks

9 ECA kept intact even in the failed area Number marked points were opened to check the failure mechanism ECA kept intact and its alignment on the cell was good Discoloring of copper parts, EXCEPT at the ECA locations Full size module can limit moisture penetration with better seal and alumina frame on the edge 6 was bad contact 5 was good contact

10 Full size modules made with PV-5802 at Tianwei on Eurotron line show high efficiency Joint experiment Dow Corning - Tianwei Tianwei multicrystalline MWT cells Conductive backsheet with ILD and OSP finish Automated MWT module assembly line from Eurotron High efficiency modules : V OC (V) I SC (A) FF (%) Eff. (%) P max (W) Average Best module Full area efficiency, complete modules with frame and junction box. Module area : m 2

11 Relative module power (%) Relative module power (%) Full size modules behave extremely well in accelerated aging tests Passed 3xIEC requirement! 105% 105% 100% 100% 95% 90% IEC requirement<5% power loss 95% 90% IEC requirement<5% power loss 85% 85% Time in damp heat conditions (hours) TUV certification Number of thermal cycles

12 Relative module power (%) Conclusions PV-5802 : New silicone ECA developed for MWT modules, suitable for automated MWT module assembly line and OSP-finished conductive backsheets Low contact resistance, low CTM losses Outstanding durability, full size module passed 3xIEC requirement Full size modules certified by TUV 105% 100% 95% Aluminium frame Silicone sealant Backsheet Front EVA Copper foil Glass IEC requirement Punched back EVA MWT Cell Electrically Conductive Adhesive 90% 85% Number of thermal cycles

13 Thank you! The information provided in this presentation does not constitute a contractual commitment by Dow Corning. While Dow Corning does its best to assure that information contained in this presentation is accurate and fully up-to-date, Dow Corning does not guarantee or warranty the accuracy or completeness of information provided in this presentation. Dow Corning reserves the right to make improvements, corrections and/or changes to this presentation in the future. and TM indicate trademarks of Dow Corning Corporation