Vernie Everett, Andrew Blakers, Klaus Weber, Evan Franklin

Handling, Assembly, and Electrical Interconnection of 2nd 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.

0.04 to 0.1mm pitch

0.1mm

2mm

100mm

Illu

min

atio

nIll

um

ina

tion

~1,000 completed bifacial SLIVER solar cells, each ~ 2 cm2

Cuts

Sliver Solar Cell

Cross-Section

Illumination

Illum

inat

ion

Perfectly bifacial

Metal (n-electrode)

Metal (p-electrode)

Boron diffusion

Phosphorus diffusion

Surface texturing Phosphorus diffusion AR coating

20-50m 1-2mm

A 2nd 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• 1st Generation SLIVER cell fabrication required 59 steps• 2nd 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 2nd 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 2nd 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 2nd Generation SLIVER Technology 3. SLIVER electrical interconnections (ctd.)

A 2nd Generation SLIVER Technology

A SLIVER module constructed using Raft Sub-module Technology

A 2nd Generation SLIVER Technology

Reduces silicon consumption by a factor of 10 - 20 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 2nd 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:

Thank You!