Vernie Everett, Andrew Blakers, Klaus Weber, Evan Franklin Handling, Assembly, and Electrical Interconnection of 2 nd Generation SLIVER Solar Cells

3D 2D

Silicon wafer single crystal 150mm Ø 1-3mm thick 100mm Grooves formed through the wafer Following grooving, wafer processing proceeds: Diffusions, oxidations, depositions, metallisation to 0.1mm pitch

0.1mm 2mm 100mm Illumination ~1,000 completed bifacial SLIVER solar cells, each ~ 2 cm 2 Cuts

Sliver Solar Cell Cross-Section Illumination Perfectly bifacial Metal (n-electrode) Metal (p-electrode) Boron diffusion Phosphorus diffusion Surface texturing Phosphorus diffusion AR coating  m 1-2mm

A 2 nd Generation SLIVER Technology  Reduce Grooving Pitch and SLIVER Thickness Strong cost driver Major challenges Advantage: with 40 micron pitch, 2.5X surface area increase over 100 micron pitch, at near-zero cost increase.  Reduce SLIVER Cell Fabrication Complexity 1 st Generation SLIVER cell fabrication required 59 steps 2 nd Generation SLIVER cell fabrication requires only 32 steps Simplify texturing, improve light-trapping and AR-coating  Broaden Process Windows and Improve Yield and Efficiency Robust processes with broad process windows Improve yield: essential for simplified handling and assembly Improve efficiency. Long term, efficiency will be the deciding factor 1. SLIVER cell fabrication

A 2 nd Generation SLIVER Technology  A fundamental change in handling philosophy Abandoned individual, sequential linear processes. Moved to group handling modular parallel processes. Improved yield through simplified separation, “bulk” handling, and a simplified structure. Improved throughput with modular process line, with input and output buffers.  Modular sub-assemblies Conventional cell “analogues” Avoid individual testing and binning  Versatility through modularity Two main sub-assembly types: “Rafts”, and “Sheets”. Separation and handling processes are common for both. Applications are common for both: cost and efficiency are the only differences. Rafts and Sheets can be the building blocks of all SLIVER applications. 2. SLIVER handling and assembly

A SLIVER Raft

A Flexible SLIVER Raft

Flexible SLIVER Raft Assembly

SLIVER cells Soldered electrical interconnections  Simplified process Eliminated stencilling Eliminated dispensing Eliminated cleaning and waste Eliminated machine vision Eliminated complex automation  Robust process Simplified alignment requirements “Automatic” solder volume and location and distribution  Conventional materials reliability, durability, warranty A 2 nd Generation SLIVER Technology 3. SLIVER electrical interconnections  Equipment: low-cost, low-tech, industry-standard.  Process: robust, modular, buffered.  Materials: conventional, low-cost, reliable.  Throughput: 500 – 1,000 connections per second. Advantages:

A 2 nd Generation SLIVER Technology 3. SLIVER electrical interconnections (ctd.)

A 2 nd Generation SLIVER Technology A SLIVER module constructed using Raft Sub-module Technology

A 2 nd Generation SLIVER Technology  Reduces silicon consumption by a factor of  Reduces wafer starts by a factor of 20 – 40  Reduces cell fabrication steps from 59 to 32  Simplifies cell fabrication equipment requirements  Exceeds 20% cell efficiency [world first for thin production cells]  Reduces assembly equipment cost by a factor of 10  Increases assembly line throughput by a factor of 10  Increases rate of electrical connection by factor of 100  Modularises the entire assembly process  Establishes an entire assembly process using only conventional materials

A 2 nd Generation SLIVER Technology Conclusion  Reduce present PV costs by two-thirds  Rapidly grow market share  Play a significant role in ameliorating climate change Mature SLIVER Technology can:

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