Busbar and Busbar-less Heterojunction cell printing on the CEA-INES pilote line Ribbons and SWCT Module performances

Transcription

1 National Institute of Solar Energy - Solar Technologies Division Busbar and Busbar-less Heterojunction cell printing on the CEA-INES pilote line Ribbons and SWCT Module performances A. Bettinelli*, M. Anton*, C. Bouet*, J. Diaz*, N. Rey*, B. Commault*, P. Lefillastre*, H. Colin*, L. Sicot*, B. Bonnet-Eymard** * CEA-INES, National Solar Energy Institute (INES), 50 avenue du Lac Leman, Le Bourget-du-Lac, France **Meyer Burger AG, Schorenstrasse 39, 3645 Gwatt (Thun), Switzerland Metallization & Interconnection workshop, Konstanz, 24 Oct. 2017

2 Outline 1 PV activities at CEA-INES 2 The CEA-INES SHJ pilot line ( LabFab ) 3 Printing of Busbar and Busbar-less SHJ cells 4 BB0 and BB4 cells performances 5 Module Reliability 6 Module Performances (Outdoor results) 7 Conclusion 2

3 1 PV activities at INES - R&D on the whole value chain Bifaciality Reliability Certification Bankability Production Yield Bifaciality SHJ, PERT SYSTEM DEMONSTRATION MODULE Demonstrators CELL > 23% IVGT Ribbons, wires > 390 Wp 72 cells INGOT WAFER > 22% IVBB 3

4 2 The CEA SHJ pilote Line Incoming Controls WET PECVD PVD Transport of wafers in carriers and motorized belt trolleys 2400 w/h capacity / TRL 5-8 Dedicated room for metallization Screen-printing IVBB or IVGT Sorter 4

5 3 SHJ Screen printing - Low T paste specificity HOMOJUNCTION HETEROJUNCTION Specific curing oven for long curing times INES: curing in cassette Very short firing (<10 sec) around 800 C Low paste resistivity 2-3 µω.cm Long curing around 200 C High paste resistivity => critical for 3-4 BusBar cells Until 2015: Paste resistivity very sensitive to the curing time: C mandatory for 4 BB cells. Bad resistivity below 200 C => Oven T homogeneity critical Adhesion provided by the glass Criticity: R contact Adhesion provided by the organics R contact not so critical Critical for ribbons soldering => CEA-INES processes: - Ribbons: Interconnection by ECA (soldering under evaluation) - Wires: Smartwire technology (MBB not compatible) 5

6 3 SHJ Screen printing of Low Temperature pastes HETEROJUNCTION Low Temperature paste Curing temperature; Curing time Paste resistivity Aspect ratio Until 2015 Long curing time 15-20min Rho 7-10 µω.cm Very sensitive to the curing time 4BB => Double print used at INES until 2015 Now Resistivity less sensitive to the curing time and to the curing Temperature Good resistance even with C or below Rho 4-6 µω.cm proposed by several suppliers Less sensitive to the curing time High aspect ratio paste available But printability not so easy => Single Print now used at INES for BB cells Studies on screen design, printing process Adhesion provided by the organics 2 Interconnection processes optimized at CEA-INES: Ribbons: Interconnection by Electrical Conductive Adhesive (ECA) Wires: SWCT (MBB not compatible) 6

7 3 SHJ Screen printing Printing data BB4 BB0 60 µ - thick IV tester For cells with BB SP - Deposit 50-75mg R 1cm finger = 0,6-0,9 Ω Ag / 3 Industrial printings No finger interruption without any screen cleaning (stop not critical) SP - Deposit 20-25mg R 1cm finger = 2,0-2,5 Ω IVGridTouch for BBless cells 45µ - thin Continuous lamp + shutter Short flash, hysteresis method also validated. Grid resistance integrated Gridtouch contacting unit (wires both side), PCBTouch contacting unit (wires on top) 7

8 4 SHJ Screen printing IV data on paired precursors 60 µm Paired cell precursors Size M2 Δ Eff 0,9% abs. 45 µm BB4 BB0 Eff 21,57% IV 4BB Eff 22,45% IVGT BB4 Uoc FF Isc Eff IVBB average 0,735 79,2 9,057 21,57 Same Isc after interconnection and lamination with LHS ribbons (structured ribbons require a single axis tracker FF 79,2/80,6: Δ Eff 0,4% finger 60/45: Δ Eff 0,2% But no additional shadowing with the LHS ribbons UV clear encpasulant BB0 Uoc FF Isc Eff IVGT average 0,735 80,8 9,230 22,45 FF correction R finger 2Ω/cm 80,6 22,38 Effective But wire shadowing during the interconnection Efficiency Isc after the interconnection and lamination (wire shadowing) 18 wires Ǿ200 9,109 22,09 18 wires Ǿ250 9,072 22,00 18 wires Ǿ300 9,035 21,91 Δ Eff 0,3-0,5% abs. 8

9 5 Module Reliability Good reliability achieved with the 2 technologies: Δ Pmax < 2% after 200 TC, 1000h DH, Cell and Module process optimizations allow to get low Pmax variations during reliability tests. Influence on BB cells Bbless cells Bbless cells the module + Ribbons + Wires + Wires reliability 1,2 x0,2 LHS Ǿ 200µm Ǿ 300µm Cell paste low low medium printing quality no impact low medium Interconnection Cu coating linked to ECA medium medium & Module Encapsulant medium low medium Reliability data for GG SHJ swct M0 Modules Batch of 20 modules evaluated in reliability and outdoor (next slide) Pmax variation (%) Irradiance (W/m²) TC DH 9

10 6 Modules performances (Outdoor results) Bifacial, Monofacial Array Ratio is a measure of the system productivity Cells 2016 Size M0 Location: INES - Chambery Albedo 0,4 Surface Ratio 100% 127% 102% 106% 124% Surface Ratio is a measure of the system power density SHJ-systems monitoring during long-term production, benchmarked to other cells technologies: Production yield, Bifaciality, Degradation factor, Bankability Excellent surface ratio, same level as the IBC modules, even with these 2016 SHJ cells size M0 Average SHJ cells: 2016 M0 5,2 Wp; 2017 M2 5,5 Wp IVGT 10

11 7 Conclusion Two types of SHJ metallization available at the CEA-INES pilot line : BB and SWCT. Using paired precursors, cell performance of the two approaches were compared and we evaluated : gap linked to the difference in IV measurement gap linked to real performance at the module level => Similar module powers with a clear advantage for SWCT versus 4BB approach in term of cost (Ag deposit x3, significantly reduced with the increase of the number of BB) Good module reliability with the 2 types of cells, illustrated by very stable GG SWCT modules. These SWCT modules were evaluated Outdoor. The benchmark with other technologies shows that: Monofacial SHJ SWCT exhibit higher productivity than other monofacial technologies. Energy productivity is even higher for bifacial SWCT SHJ in real field conditions. Potential for higher performances and lower costs are on going for both technologies at INES. Roll to Roll (Wire placement on foil) and SWCT Stringer now available at CEA-INES 11

12 THANKS FOR YOUR ATTENTION Acknowledgement to: CEA INES cell & module & system teams ; Meyer Burger module team 12