1. Prof. Dr. Franz Baumgartner Energy Systems NTB Hochschule für Technik Buchs, NTB, Switzerland Future and further development of silicon thin film technology: prospects for R&D

2. 2 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv 1 Solar cell market  PV share of total electricity generation  EU target 2020 – RE 20%  Limits of growth

3. 3 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv PV market over time Today  EU target 3GWp for 2010 already reached  Thin film share <10%  PV electricity share today: Bavaria 1% EU approx. 0.1% World approx. 0.04% Expansion plans  PV no effective expansion limit compared to water, wind, biomass  Exception CIGS approx. 80 GW limit 0.5% global electricity consumption Source: Heinz Ossenbrink, EU-JRC, Ispra; Dübendorf talk, Switzerland on 2007-03-16 EU Ziel 2010

4. 4 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv 2 Efficiency of solar cells  Physical boundaries  Record laboratory cells  Products

5. 5 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv Baumgartner, NET conference articles, NTB; 2002 Thin film efficiency levels 90% of all crystalline standard modules with efficiency levels <14% !

6. 6 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv 3 Criteria for sustainability of thin film solar modules with big chances of growth  Environmentally and climatically compatible components Low use of materials and energy Energy payback periods < 2 years  Resources enable solar share > 20% in global electricity generation, otherwise niche product  Economic mass production

7. 7 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv 4 Option: silicon thin film  Creation of film structure  Film deposition  Light traps

8. 8 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv In 1994, J. Meier (now CTO, Oerlikon Solar) produced the first µc-Si solar cell: This was the breakthrough for a-Si tandem structures Efficiency >10%, Reduction of degradation People do research with feeling! Source: J. Meier; J. Appl. Phys. L; 1994; this is the most important publication of the last 20 years for thin film silicon a-Si laboratory cell 9.5% stab. world record J. Meier et. al. a-Si /µc-si laboratory cell 11.7% stab. mod. tripel. cell 15% initial

9. 9 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv Sources: [1] Vanecek, Euro PV Conf, 2003 [2] Progress in PV, 2007, 15, p35; Eff. Table, No 29; Oct 2006, [3] A. Shah, Prog. PV, 2004 Status laboratory cells (Ref. [2, 3])  µc-Si: 10.1% with 2 µm thickness (0.57 I max,theo ; 24.4mA/cm 2 STC)  a-Si: 9.5% with 0.25 µm thickness (0.85 I max,theo ; 17.5mA/cm 2 STC 0.66 Voc max,theo ) Development potential – Isc uc-Si  Front TCO film  Interlayers, back-reflector Summary  More light trapping  Thinner Si layer possible  Shorter coating times – lower costs The light trap is a must! Interlayer Glas

10. 10 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv 5 Potential: silicon thin film Maximum efficiency levels  a-Si: today laboratory cell 9.5%, modules 7% (8.6% initial)  a-Si: forecast 2015 modules < 9%  Tandem a-Si/µc-Si: estimated efficiency 1.25 times higher than stable a-Si single cell  Tandem today laboratory mini module 11.7% stable Initial efficiency for laboratory miniature cells >13% initial  Tandem 2015: modules > 12%

11. 11 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv Converting R&D potential into industrial production! More efficient light traps Even faster silicon deposition New quality measuring technique urgently needed to improve production, uniformity A. Jäger Waldau, NTB, 2002

12. 12 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv Measuring and optimizing Collaboration  NTB, FH Buchs  EU JRC, Ispra  Oerlikon Solar Measuring of  Indoor; IV test, spectral photovoltaic current  Outdoor, energy yield a-Si 60% output uc-Si 40% output Photovoltaic current of the tandem cell

13. 13 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv 6 The solar power plant operator doesn’t want output in Wp but energy in kWh Advantages of low temperature coefficients

14. 14 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv Performance at 50°C counts!  Temperature coefficient of cr-Si : -0.44 %/°C  Temperature coefficient of a-Si:H thin film : - 0.22 %/°C Fazit  1 MW a-Si STC output delivers around 6% more yield than 1 MW cr-Si cr-Si P N =100 W STC 25 °C a-Si P N =94 W STC 25 °C P=89 W at 50 °C Temperature loss cr-Si -11 % Temperature loss a-Si -5.5 %

15. 15 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv 7 What module efficiency is economic only planners of PV power plants know! or more simply: Module efficiency isn’t everything!

16. 16 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv Costs ground-based power plants Inverter 0.3 €/W Modules 3.1 €/W 60% of total costs Planning, various 0.3 €/W Assembly m+e 0.5 €/W cr-Si standard η M =13% 4.2 €/W Thin film η M =6.5% 4.2 €/W 0.3 €/W Module 2.6 €/W 1.0 €/W Cost structure 2007 Inst. costs 4.5€/W in 2006 0.3 €/W 2.4 €/W 1.0 €/W 4.0 €/W

17. 17 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv Costs for PV power plant investors

18. 18 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv Source: Wim Sinke, WG3, Euro PV Technology Platform, Brussels, 2006 2010 2020 Solar market Europe: grid parity

19. 19 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv Source: S. Nowak, IEA PV Program; Task 2; EU Conf. Dresden, Sept 2006 IEA Very Large PV plants

20. 20 Prof. Dr. Franz Baumgartner 2007-06-14; www.ntb.ch/pv Thank you for your attention