GT Advanced Technologies has announced the commercial availability of its DSS 450 MonoCast crystal growth system. Modules produced from material grown in the furnace are claimed to rival modules that incorporate traditional boron-doped batch CZ monocrystalline wafers in terms of total output. The DSS450 MonoCast furnace incorporates a number of new features that result in ≥80% mono volume yield per slabbed ingot and significantly increases Grade I wafers (>90% mono area/wafer) per ingot than other cast mono technologies.
Although boron-doped batch CZ monocrystalline wafers offer higher purity and provide higher cell efficiencies, compared to conventional multi-crystalline wafers, production costs are significantly higher. There is a need to provide multi-crystalline type wafer production costs without sacrificing purity and performance.
Modules produced from GT’s MonoCast material are claimed to rival modules that incorporate traditional boron-doped batch CZ processed monocrystalline wafers in terms of total output. Cells produced from DSS450 MonoCast wafers are claimed to have lower Light Induced Degradation (LID) and the full square surface dimension area across the wafer provides greater electricity generating surface area than the pseudo square shape of traditional monocrystalline wafers. A typical MonoCast ingot produces three grades of wafers: Grade 1 which is nearly all mono, Grade 2 a hybrid wafer with more mono than multi and Grade 3 wafers, which are more multi than mono. Based on the recent field trial results, GT’s MonoCast solution delivers greater than 80% mono volume yield per ingot, with over 95% of all wafers being Grade I and II. GTAT has also developed a post processing technique, which is claimed to significantly increase the number of Grade I wafers per ingot well beyond that possible with any other commercially available monocast technology. Ongoing work on material science and cell architectures with the Georgia Institute of Technology was said to have demonstrated, that MonoCast material when combined with advanced cell processing technology can deliver efficiency conversions of greater than 19%. The result is module efficiencies that are competitive with modules incorporating batch monocrystalline wafers.
‘MonoCast’ or ‘quasi-mono’ wafer production.
The DSS450 MonoCast features new advanced hardware and an industry first automatic seed retention feature that eliminates dipping and operator intervention between melt and growth helping to automate the process and enabling the production worthiness of the DSS450 MonoCast system. When combined with GT’s new ‘Acuity’ performance software, the DSS450 MonoCast can produce high quality ingots run after run.
The MonoCast technology is being offered first on GT’s DSS450 and DSS450HP systems. Customers currently operating these DSS furnaces can migrate to the new DSS450 MonoCast system through a field upgrade, which is expected to be at a cost below US$100,000 per system.