Welcome to SCHOTT Solar

SolarInnovativ Thüringen Welcome to SCHOTT Solar Europe's largest producer of PV solar electricity components EFG, ein kostengünstiges Produktionsverfahren für Si-Wafer Dr. Ingo A. Schwirtlich SolarInnovativ Thüringen 25. / 26. Oktober 2006 1

SolarInnovativ Thüringen The SCHOTT Synopsis *! " # $% % % & # 2

AEG Telefunken DASA 50% MBB PST NUKEM 50% 100% NUKEM GmbH ASE GmbH 100% TESSAG 100% RWE Solutions AG RWE Solar GmbH Joint Venture RWE Solutions SCHOTT Glas SCHOTT Solar GmbH RWE SCHOTT Solar GmbH Mobil Tyco Solar Energy Mobil Solar Energy ASE Americas Inc. ASE Americas Inc. RWE SCHOTT Solar Inc. 1960 1970 1980 1990 1994 1996 1999 2001 2002 2005 3

SCHOTT AG SCHOTT Solar Group Employess: ca. 900 world-wide Turnover: ~320 Mio. in 2006 (forecast) SCHOTT Solar GmbH Subsidiaries 100 % SCHOTT Solar, Inc. Billerica (MA) USA Fully integrated production of wafers, cells and modules SCHOTT Solar Inc. Rocklin (CA) USA System integration Sales of modules and systems RWE SCHOTT Solar CR Valasske Mezirici, CR Production of modules Alzenau, Headquarters Fully integrated production of wafers, cells and modules Phototronics (PST) Putzbrunn Production of thin film modules Jena Buildup of a 30 MW production line of ASI thin film modules 4

SmartSolarFab - Alzenau OEM Zellenfertigung Heilbronn, D 5

The Value Chain of the SCHOTT Solar Group Modules Cells Wafer 6

17% 18 % 10 % 25 % 15 % poly Si Wafer Cell Module BOS 24% (15) 26% (25) 14 % (20) 36% (40) 100 % (100) Increasingly important is the industry to produce manufacturing equipment and materials for the whole value chain. 15 % Installation 100 % Today's 2005 Value Added Chain for grid-connected PV Systems (2004 in brackets) 7

Relative Module Manufacturing cost as Function of Efficiency relative module cost (%) 130 120 110 100 90 80 70 mc = 1 EFG = 0.7 mc CZ/Ga = 1.5 mc CZ/B = 1.35 mc 10 12 14 16 18 20 22 24 Efficiency [%] 8

Advantages of ribbon technologies 5 Energy Pay-Back Time [a] 4 3 2 1 BOS frame laminate 0 ribbon S-Eur. ribbon M-Eur. multi S-Eur. multi M-Eur. mono S-Eur. mono M-Eur. From: E. Alsema et al. 20th EUPVSEC 2005 9

Estimated reduction of silicon consumption 16 14 g Si/Wp 12 10 8 15 % EFG 85 % mono / multi - Si mono / multi - Si 6 4 EFG 2 0 2005 2010 2015 2020 2025 Specific feed stock consumption per Wp for different wafer technologies 10

Si - Blockguß 11

Blockguß-Anlage Deutsche Solar Freiberg 12

Silicium - Block Abmessungen: 66 cm x 66 cm Gewicht: ca. 250 kg 13

Säulenherstellung Deutsche Solar Freiberg 14

Drahtsägetechnik slurry & abrasive ingot main drive slave drive wire web Typische Sägeparameter Drahtdurchmesser 150-250 µm Drahtgeschwindigkeit 5-15 m/s Öl- oder Glykol-basierte Slurry SiC Vol. Anteil 30-60% 15

Multikristalline Silicium - Scheiben Multikristalliner Wafer aus dem Blockgußverfahren EFG-Wafer nach dem Folienziehverfahren von SCHOTT 16

SmartSolarFab - Wafer Production EFG-Wafer Production (Edge-defined Film-fed Growth) 17

Productivity Increase and Cost Reduction for c-si Wafers 1990 Actual 2003 1. Step 2. Step 3. Step Long-Term Si-Material Wafer Thickness [µm] 450 300 200 150 100 50 (-83%) EFG-Wafer Tube circumference [dm] 9x0,5 4,5 8x1 8 8x1,25 10 12x1,25 15 12x1,5 18 circle 1,3m 40 Productivity 0,6 1(norm.) 1,2 1,9 2,2 5 Material add-on 2 1 1,2 1,7 2 4 (-20%) Personnel 1,5 1 1 1,1 1,2 1,3 (-74%) Depr/Interest 1,5 1 1 1,1 1,2 1,3 (-74%) 18

EFG history v. Gompertz 1922: Growth of metal wires from a wetted capillary. LaBelle 1971: EFG of sapphire tubes. Ciszek 1972: EFG of silicon ribbons. Taylor 1981: EFG of polygonal silicon tubes (nonagons with 50 mm faces). 19

EFG of silicon octagons Wald 1985 (Mobil Solar Energy): EFG production of silicon octagons with 100 mm faces. RWE SCHOTT Solar 2003: EFG production of silicon octagons with 125 mm faces. 20

Edge-defined film-fed growth (EFG) v s t Crystal thickness t = f(v s, T, h, wetting angles) Fixed: h, wetting angles Control parameters: v s, T melt crystal 1412 C wetting angles T die h melt (T melt ) T 21

EFG crystal growth: schematic Silicon Tube Octagonal Die Molten Silicon Induction Heater 22

125 mm EFG: scales 7 m 0.3 mm 125 mm 23

SOLAR 100 mm and 125 mm octagons Increase of throughput by more than 25 %. No loss of materials quality. No increase of wafer thickness. 0 10 20 30 cm Increase in productivity by growing 125 mm wide faced octagons instead of 100 mm 24

Cutting of tubes by laser for wafer production Several tubes per day and furnace up to 7 m length. Less than 10 % silicon loss at cutting step. Wafers are immediately processed after light etch. 25

6x150mm growth First 150x150mm samples 100x100 125x125 150 x 150 26

EG wafer properties: carrier lifetime distribution As grown lifetimes up to 10 µs. The distribution mainly correlates to dislocation density variations. 27

Access Buckling 28

Advanced process modeling: 3D stress and strain tensile 45 MPa v stress compressive -45 MPa Non-uniform cooling of edges and faces can result in tube deformation during growth. Danger of remaining deformations by residual stress, creep and plastic deformation. interface In collaboration of ACCESS e.v., Aachen 29

Latest stage of development: Dodekagons Oktagon 125 mm Dodekagon 125 mm 30

200 micron thin EFG silicon wafers 31

EFG wafer properties: mechanical strength 100 90 Failure rate [%] 80 70 60 50 40 30 20 10 mc - Si as grown mc - Si damage etched EFG as etched 0 0 100 200 300 400 500 600 700 800 900 1000 1100 Fracture strength [MPa] Biaxial test: fracture strength of 550 MPa (60% failure rate value) for EFG. As-grown surface is free of serious damage. In collaboration with TU Freiberg 32

Wafer breakage? Elaborated crack free edge design and stress free volume is required to minimize breakage of thin wafers. 33

SOLAR EFG wafer properties: wafer edge As cut, 4 min Sirtl etched Standard etched 34

SmartSolarFab - Cell Production EFG-Zelle EFG-Zelle MAIN-Zelle MAIN-Zelle 100 x 100 mm 2 125 x 125 mm 2 100 x 100 mm 2 125 x 125 mm 2 35

Process sequence for the fabrication of EFG solar cells Wafer cleaning P - doping Oxide-etching ARC-deposition Rear side metallisation Front side contact Final inspection Solder pads Al-contact & Firing 36

SmartSolarFab - Module Production High Quality Modules ASE-275-DG-FT 37

SolarInnovativ Thüringen Many thanks for your attention 38