RCT-Peter FATH

RCT Solutions GmbH – The Technology Company Recent Results of Inverted Pyramid Textured Monocrystalline Solar Cells Using an Inline MCCE Process RCT Solutions GmbH – The Technology Company RCT covers the full range of Photovoltaics: from production technology and equipment to PV systems and energy storage Solar Power PlantSolar Cell Techn. Equipment. Factory Projects Solar Inverter, Battery, Module Affiliate: Jiangsu RCT Solutions Equipment Production Affiliate: Jiangsu RCT Power 100KW to MW Energy Storage System Production • 10 GW RCT wet chemical equipment in mass production • RCT one of the market leader in MCCE texturing technology and equipment • Setting up of first solar cell factory in Turkey with RCT bifacial multi Si technology • Technology partner for largest 1GW solar factory in India applying RCT mono PERC technology • Successful market launch of highly efficient integrated solar battery inverter • Novel battery storage tool for up to 9kWh with modular concept developed • Pilot production in Konstanz, Germany • Mass production in Suzhou, PRC by RCT POWER China RCT Solutions GmbH – The Technology Company RCT i-BlackUpgrade ‣ Compare to standard alkaline mono-texture the inverted pyramid texture shows much better optical performance in terms of reflection and light trapping; ‣ Till now most promising results are reached by using of Cu or Cu+Ag based MCCE process with application of HF:H2O2 etching solution at process temperature about 50oC. Main disadvantages of current process are: ‣ process time about 15 min; ‣ usage of H2O2 at 50oC follows for accelerated and non-controlled H2O2 evaporation – difficulties to secure stable texturing process for industrial application; ‣ usage of Cu-based MCCE etching solution has limited acceptance for PV production due to a risk of Cu-contamination. RCT Solutions GmbH – The Technology Company New mono-Texture: RCT Process ‣ RCT approach for inverted pyramid texture: ‣ Application of Ag-based MCCE process – no risk of Cu-contamination; ‣ Usage of H2O2 –free etching solution (HF/HNO3) – well known stable process for industrial application; ‣ Total etching time below 5 min – well applicable for both batch and in-line high throughput equipment; ‣ Process temperature does not exceed 70oC – reduced stress for hardware, improved process control; ‣ Adjustment of pyramid size and depth by process recipe resulting in different reflectivity and light trapping behaviour – well applicable for different solar cell structures. New RCT mono-TextureEtch depth: 3,5µm/side; av. reflect. range: 10-8% RCT Solutions GmbH – The Technology Company Process Flow Ag Si Si Si Si SiSi Ag Ag 1. 2. 3. 4. 5. 6. As cut Si wafer Deposition of Ag particles Hole driling Etching Step 1. Removal of Ag particles Etching Step 2. RCT Solutions GmbH – The Technology Company RCT Texture Process Example : In-line approach Input Ag deposition and hole drilling Rinse Etching Step 1 Etching Step 2Ag removal Rinse Rinse Dryer Output Rinse HF/HCL metal cleaning Rinse RCT Solutions GmbH – The Technology Company Two-steps Textur Formation Etching Step 1: forming of inverted pyramids Etching Step 2: shaping of inverted pyramids RCT Solutions GmbH – The Technology Company New RCT mono-Texture: average reflection 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 300 360 420 480 540 600 660 720 780 840 900 960 1020108011401200 REF L [% ] Wavelength (nm) Reference. Av. Ref. 12% Inverted pyramids. S. 1. Av. Ref. 10% Inverted pyramids. S. 2. Av. Ref. 8,2% Inverted pyramids. S. 3. Av. Ref. 6,2% ‣ Optical performance of new RCT inverted pyramid texture: ‣ By variation of process parameters (concentration, temperature, time ) the reflection of mono texture can be significantly reduced. ‣ In opposite to standard mono texture the structure (size, depth) of new RCT inverted pyramid texture is more flexible. ‣ The main benefit of reflectivity reduction is coming from 400- 550nm wavelength range – most effective for modern shallow or selective emitters. RCT Solutions GmbH – The Technology Company New RCT mono-Texture: optical appearance Up-right pyramid texture Inverted pyramid texture RCT Solutions GmbH – The Technology Company Inverted pyramid texture Up-right pyramid texture New RCT mono-Texture: anisotropic behavior RCT Solutions GmbH – The Technology Company Textur structure New RCT mono-Texture Typical size of pyramid base: 600 – 900 nm. RCT Solutions GmbH – The Technology Company New RCT mono-Texture: polished rear side ‣ Additional benefit of RCT inline mono-texture is a polishing on the wafer rear side. Inverted pyramid texture Up-right pyramid texture Rear side of inverted pyramid texture RCT Solutions GmbH – The Technology Company ‣ Industrial solar cell run performed with wafers textured by RCT Inverted Pyramid Texture process shows big potential of new texture compare to reference up-right pyramid texture. ‣ High Voc value confirms perfect ability of Inv. Pyramid Texture for surface passivation. ‣ Isc value over 9.6A was reached and it’s comparable with Isc of perfect alkaline textured solar cells. ‣ Contact resistance is clearly a limitation for standard alkaline texture while Inv. Pyramid Texture due to higher surface (contact) area allows much lower contact resistance, Rs and higher FF. Mono PERC Centaurus II Isc Voc FF Eta Rser Rshunt Irev2 Inverted vs. Up-right Pyramid Texture D abs. 0 A + 3 mV + 1,0% + 0,35% - 0,6 mOhm + 50 Ohm + 0,01A D rel. 0% + 0,5% + 1,2% + 1,7% - 18% + 44% + 4% New RCT mono-Texture: solar cell performance RCT Solutions GmbH – The Technology Company ‣ EL picture shows absolutely uniform and effective emitter and confirms a possibility of future increase of the emitter sheet resistance; ‣ Due to higher surface/contact area the increase of Rem, resulting in higher Voc and Isc, is possible without FF loss. ‣ Future Isc increase can be achieved by improvement of Inv. Pyramid density. New RCT mono-Texture: potential for improvement RCT Solutions GmbH – The Technology Company Thank you for your attention! RCT Solutions GmbH Line-Eid-Str. 1 78467 Konstanz GERMANY