Milpitas, CA--Solar energy startup Solexel revealed the technology behind its thin-silicon (not thin-film solar like CIGS) solar cell technology at the recent Intersolar North America 2012 conference in San Francisco, CA. Unlike conventional crystalline silicon solar cells made from polysilicon ingots and wafering processes, Solexel deposits inexpensive trichlorosilane gas on a reusable mono-crystalline silicon template in an epitaxial process, growing mono-crystalline silicon wafers with a 35 micron thickness.
The wafers are supported throughout the cell process, initially by the reusable template, and further in the process by a low-cost, flexible backplane that is attached to the back of each wafer. A proprietary tool releases the ultra-thin cell from its reusable template, which can be reused more than 50 times, without any degradation in cell performance. Solexel produces full-square, 156 x 156 mm back-contact cells--that they say are the world’s largest ultra-thin crystalline silicon solar cells. The company has proven cell efficiency of 19% in its fab, a world record on thin silicon, and has a roadmap towards 23.5% cell efficiency and 22% module efficiency. Thanks to the elimination of the high-cost, high-CAPEX process steps in the traditional silicon value chain, Solexel will manufacture solar PV modules at scale at a cost of $0.42/Watt.
In addition to providing support to the cell, the backplane enables pliability of Solexel's cells, similar to other thin-film solar cell technologies amenable to roll-to-roll processing. This leads to the avoidance of cell breakage and enables innovative, flexible module designs. Furthermore, the backplane material is well suited for the integration of electronics to the back of the cell, to deliver cell-level shade management capabilities.
Solexel was incorporated in 2007 and has a fully operational pilot fab in Milpitas, CA. The company has attracted funding from Kleiner Perkins Caufield & Byers, Technology Partners, DAG Ventures and Northgate Capital and recently received an investment from SunPower. A Series C fundraising round is currently underway, and $37M has already been raised in this round, from new investors Gentry Venture Partners, GSV and SunPower, as well as existing investors. The proceeds of the Series C fundraising will be used to build a copy-exact manufacturing line in Milpitas, to prove high-volume manufacturability. Large-scale manufacturing capacity will be built in Malaysia, where the company has signed an MOU for the construction of a plant with capacity of up to 1 GW.
The company has signed up a select group of top-tier developers and distributors, and its early-years manufacturing volume is fully subscribed by these customers. Furthermore, Solexel is working exclusively with Owens-Corning on a BIPV solar roofing shingle, with support from a $13M DOE grant. The company expects to begin high-volume module sales in 2014.
SOURCE: Solexel; www.solexel.com/IntersolarNA2012.php
