A method for fabricating multi-cell solar devices using thermal spray deposition techniques to spray metal powder directly on solar cells and on the backing upon which solar cells are assembled, to form collection grid lines, bus bars, electrodes and interconnections between solar cells.
The invention relates to the application of bus bars for interconnecting solar cells, and in particular to thermal spray depositing of bus bars across the grid line surfaces and the back surfaces of solar cells to form interconnections for a sequence of solar cells to make a solar panel.
The Issue with today’s Process
In the prior art process, the tabbing machine is very complex, combining mechanical parts that move and cut tabs and electrical parts that heat up the cell surface and solder the tabs. Moreover, for the soldering of tabs on the back side, an extra step is required for screen-printing the silver pads. This adds to the cost of machines and working space, as well as to production time and costs, since extra machines for printing and baking are necessary.
Summary of Benefits
Enables interconnection of cells to be completed in less time and at a lower cost than current methods
- Allows connections directly to a single- or poly-crystalline silicon solar cell and of interconnections between cells.
- Enable the interconnection of solar cells by a single apparatus instead of multiple-step, tabbing and stringing equipment as is currently practiced (no more equipment!)
Higher electrical and mechanical quality and improved solar/electric conversion efficiencies
Sprayed metal particles have high velocity and temperature, the coating made by these particles has strong bonding with the substrate materials.The thermal spray system is the only apparatus needed for the whole process.
- Replaces machines for mechanical handling and electrical soldering of tabs
- Replaces an extra screen-printing machine and a baking oven for the silver pads
- Reduces the required investment in processing equipment.
No restriction to the metal that can be used if it is available in the form of a fine powder suitable for spray techniques.
- Silver, copper, aluminum, nickel, gold or any of their alloys are good candidates and more
- Suitable thermal spray methods include any form of the commercially available spray deposition techniques, such as arc plasma spray, flame spray, HVOF, and laser spray.
This technology does sound “magical,” one spray bottle can replace equipment, soldering, printing and baking equipment. The technology will reduce weight, reduce costs and take a bite out of the metallization paste providers top and bottom lines (DuPont, Heraus, and Giga Solar Materials). The thermal spray can utilize any any fine metal powder so the application being showcased today might be for solar, but it could be broadly applied to the electronic devices and minimize the need for soldering all together. Merlin, reminds me of Willy Wonka’s patented three-course dinner inside of a little piece of gum, because one little bottle of thermal spray certainly packs a heavy punch!
~Obscure Analyst 3/13/14
Full Disclosure: I am long GTAT and have no plans to buy or sell in the next 72 hours