Oregon solar manufacturer Solaicx has manifested a very novel idea: to manufacture silicon ingots solely for solar power applications. It doesn’t seem like the most earth-shattering of ideas I know, but as a matter of fact, says Solaicx, this customization reduces the cost and boosts the efficiency of silicon solar cells.

Firstly, it is important to remember that before the solar industry took off, the vast majority of silicon was manufactured for the electronic chip industry — stereos, computers, cell phones, etc. So when solar took off it was the same semiconductor industry that served the electronics industry that began supplying the solar industry as well. And why not? They already had the experience and the equipment to do so.

And all works relatively fine, but for one thing: as effective as traditional manufacturing equipment may be, it was never designed to produce silicon ingots (the oblong block of silicon that is cut into the wafers that make up solar cells) for solar alone. Solaicx founders looked into the process and found some inherent problems, problems that were significantly affecting today’s solar cells and, more importantly, problems that could be fixed. Now, Solaicx claims, they have solved those problems.

Here is how it works: In traditional ingot “growing,” the silicon and doping agents are melted down in a crucible. Then, a seed is lowered down until it contacts the surface of the molten mixture. As the seed is raised, the silicon grabs on to it and crystallizes. The seed is gradually raised further away and, after about 12 hours, the crystallizing silicon has formed a long, pure ingot of silicon that measures around six to eight inches in diameter. This ingot is then cut into the wafers that become the primary ingredient in first generation solar cells.

Solaicx, however, sees one important problem with that process for the solar industry: as the silicon ingot is grown, the ratio of silicon-to-dopant changes, causing the resistivity (to the flow of an electric current) to change from one end of the ingot to the other. That results in a lack of consistency which costs time (for sorting out solar-grade wafers) and efficiency (inconsistency affects the overall productive power of the solar panel).

Solaicx claims to have reached optimal consistency and efficiency levels so that there is no sorting necessary and every wafer cut from their ingots will convert sunlight at the highest level possible. And all they did was design an ingot grower specifically for the solar industry. The difference? Solaicx’ system constantly feeds silicon and dopant into the crucible as the ingot grows, thus keeping levels of both consistent throughout.

Because of the high cost of electronic chips, semiconductor manufacturers for that industry never really worried about maximizing productivity or minimizing costs. They’ll make their money anyway, but for the solar industry, the silicon wafer is the most critical and costly piece of the puzzle. So optimizing productivity and reducing costs is of the utmost importance.

Hence you’re likely to find a lot of smiles at the Solaicx plant these days. The company has been awarded the Progressive Manufacturing 100 award for Innovation Mastery for its manufacturing process and several other manufacturers are asking for license to use their technique. So far, however, Solaicx is holding on tight to their prize pig.

Source: EE Times

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Posted on April 9th in Solar Products by Dan.