PV research in Neuchâtel: from high efficiency crystalline cells to novel module concepts

Transcription

1 PV research in Neuchâtel: from high efficiency crystalline cells to novel module concepts Laure-Emmanuelle Perret-Aebi, Christophe Ballif April 11 th 2014 Congrès Photovoltaïque National 2014, Lausanne

2 Competence center for research in Photovoltaics CSEM PV-center founded in 2013 First swiss technology transfer for photovoltaics with CH base funding Basic researches Advanced devices SHJ cells EPFL- PVLAB Coating technologies High efficiency c-si Modules and systems

3 PV research activities in Neuchâtel, Switzerland Silicon heterojunction (SHJ) cells High efficiency Low cost Thin-film silicon cells Ultra-low cost Module Technology & systems Aesthetic and reliable, grid Advanced use of coating technologies Plasma processes for semiconductor active and doped layers CVD (chemical vapor deposition) and sputtering doped transparent conductive layers

4 St-Exupéry, The Little Prince Please draw me the perfect solar cell and the most beautiful module 3

5 A quasi-perfect solar cell And the winner is: Would capture most of the light below the bandgap Would have membranes on both sides which collects selectively all photogenerated electrons and holes Would be be low cost Random pyramids is an excellent optical system, Passivated contacts for electrons and holes Silicon is low cost 4

6 High efficiency crystalline Si cells Silicon heterojunction cells: An excellent candidate for quasi-ideal devices With few production steps 5

7 From homo- to heterojunction solar cell Diffused junction solar cell Direct contact between absorber and metal = Recombinative contact Lower V oc Heterojunction solar cell Thin semiconductor layer between absorber and metal = Passivated contact Higher V oc 6

8 Processing sequence all processing < 200 degr. C Chemical baths c-si surface preparation PECVD I PECVD II PVD Intrinsic Doped film TCO film deposition sputtering deposition a-si:h(n/p) a-si:h(i) Metallization Screen printing and curing at 200 C 7

9 Becoming a mainstream technology? Increase R&D activities. Several groups and industries above 20% with screen-printing or plated contacts (CIC, INES/EDF, ISFH, Kaneka, R&R, LG, Hyunday,.) + activities at ISE, HZB Efficiency V oc 24.7% 750 mv [De Wolf et al, Green 2, 7 (2012).] Panasonic, Japan

10 Best screen-printed cells after optimization (4 cm 2 ) Independently confirmed results (Fraunhofer ISE CalLab) area [cm 2 ] V oc [mv] J sc [ma/cm 2 ] FF [%] Efficiency [%] n-type p-type (screen-printed contacts) Record efficiency for full SHJ p-type solar cells Best V oc : 726 mv record V oc for any p-type c-si solar cell

11 High efficiency SHJ solar cell Cell area : 4 cm 2 PECVD layers in Octopus II IO:H-ITO front bilayer TCO + AR To be compared with baseline 22% screenprinted cells Eff. 22.4% N.b. Sees also results of P. Papet al. 22.3% on 5 cells, results of INES, results of Kaneka with 24.2%

12 Rear-contacted IBC-SHJ Fully back contacted solar cells Simple process with hard mask for p and n And hotmelt print to separate TCO, 9 cm 2 solar cell Current density (ma/cm 2 ) V OC = 724 mv J SC = 39.9 ma/cm 2 FF = 74.5% Eff. = 21.5% Voltage (mv) [A. Tomasi, B. Paviet-Salomon, et al, submitted (2014).]

13 Cost of metallization move away from standard design Cu Plating [Kakeka] 5 busbars [R&R CH] J. L. Hernandez, et al. T.. D. 21st PVSEC, Fukuoka, 2011, 3A-1O-05. P. Papet et al. D. Bätzner et al. Proc. 26th EU-PVSEC 2011 Arrays of wire [Day4 MBT] Yoshida et al. Proc. 26th EU-PVSEC 2011 Cu paste [AIST, JP] Balllif et al.

14 Alternative approaches for metallization : smart wires 6 Cz Low Ag content (< 40 mg/cell) Aesthetic From Roth & Rau Research, by courtesy of Dr. B. Strahm

15 SWISS INNO HJT PROJECT sponsored by FULLY INTEGRATED 3 years PROJECT: PILOT AND DEMONSTRATION OF HJT TECHNOLOGY - Diamond wire wafering - Pilot Cell Production Line in Hauterive NE - Advanced Metallization Pilot Line - SmartWire Module Interconnection - Dedicated cell and module metrology - Outdoor monitoring of 3 generations of modules developed in the project

16 Some recent results on thin film silicon at IMT PV-Lab Thin-film silicon solar cells Light scattering at nanotextured interface Silicon Layers: 1 or 2 p-i-n junctions out of amorphous and microcrystalline Si Glass Substrate Front Electrode (transparent) Silicon Layers Back Electrode Back Reflector

17 Status of µc-si:h single junction cells 1.8-µm-thick i-layer, R c = 57% SiO x in cell design Single layer LPCVD ZnO electrodes In- house AR texture on the glass White paste back reflector P. Cuony et al., APL, 2011 G. Bugnon et al., SolMat, 2013 M. Despeisse et al., PSS-A, % (certified) S. Hänni et al., PIP 2013

18 High-efficiency micromorph cell Single 2.3 µm LPCVD front electrode 230-nm-thick top cell 60-nm-thick SiO-IRL 2.2 µm bottom cell Full SiO design for the bottom cell initial 1000 h LS Voc (V) FF (%) Jsc (ma/cm 2 ) Eff (%)

19 High-efficiency triple junction cell (initial) J SC (ma/cm 2 ) V OC = 1.89 V FF = 74.4% J SC = 9.76 ma/cm 2 Eff = 13.7% EQE top (10.01) mid (9.77) bot (9.76) tot (29.54) V (V) λ (nm) Also obtained: Jsc tot > 30 ma/cm 2 on rougher front electrode Jsc ~ 31 ma/cm 2 on replicated front structure + IO:H Voc = 1.91 V on flatter front electrode

20 High-efficiency triple junction cell (stabilized) J (ma/cm 2 ) V OC = 1.85 V FF = 72.5% J SC = 9.58 ma/cm 2 Eff = 12.8% EQE Top (9.66) Mid (9.58) Bot (9.64) Tot (28.88) V (V) λ (nm) 12.8% Stable for p-i-n aμμ triple (6% rel degradation)

21 Thin-film devices Abundant & non-toxic materials Low cost / m 2 Building integration Hot-climate environment Consumer electronics

22 Material, Process and Reliability Development of new encapsulation materials Reliability accelerating aging tests, mechanical tests, adhesion, optical properties, chemical characterization Lamination process optimization, temperature and pressure, rheology interconnection Failure mode identification, modelisation New module design Demonstrate >30 years lifetime module Electricity cost reduction

23 Building Integrated Photovoltaics (BIPV) Let s try to avoid ugly solar.

24 Building Integrated Photovoltaics (BIPV) Let s try to avoid ugly solar.

25 Building Integrated Photovoltaics (BIPV)

26 Building Integrated Photovoltaics (BIPV) Development of attractive BIPV products: Attractive dedicated modules for architects colored modules, optical effect, size, shape, dummies Multi-functional building elements building skin, insulation, windows. Archinsolar project

27 Mission: enabling massive PV deployment PV system performance Evaluation of components and topologies Operation and maintenance strategies Distributed energy storage: Characterisation of components Control strategies Residential micro-grids Product development for application-specific PV systems

28 Potential of PV in Switzerland Well oriented roofs in Switzerland 30% of yearly electricity needs with 12% modules =130 km 2 roofs or less than 3 % of built surface Minimum impact on the landscape

29 Thank you for your attention