PV's "Moore's Law" Required To Drive Increased Material Efficiency

Figure 1: PV module demand driven by government subsidy. Individual countries of note: Germany's EEG feed-in tariffs survived a review in 2008; Spain is restructuring its subsidy law for 2009; Greece's newly drafted feed-in tariffs will take time to implement; and the next US administration likely will support some sort of alternative energy legislation, leading to growth in 2010. (Source: Linx Consulting)

Most input materials for PV production are in relative oversupply and will not constrain production, Thirsk pointed out — and for this reason manufacturers are conservative about capacity investment. In particular, his PV module production forecast (see Fig. 1, above) shows an overstep in demand in 2008. One reason for suppliers' reluctance to build capacity for entering the silicon supply chain is that it is an inefficient process. "Only about 15% of all the silicon going into the supply chain goes into the wafers, so it's a pretty wasteful and capital intensive process, so there is a lot of reluctance to build capacity," said Thirsk. Despite the efficiency challenges, Thirsk's forecast indicates that an oversupply may occur in 2009 (see Fig. 2, below).

Global survey of announced polysilicon capacity vs. demand (assumptions made about actual production capacity). Silicon efficiency derived using the Linx Si cell roadmap. Demand-based forecast implies an oversupply may occur in 2009. (Source: Linx Consulting)

Because >40% of PV grade silicon is lost at the wafering step, Thirsk believes this represents a significant opportunity for the right technology. Additionally, diamond wire is a potential replacement for slurry technology, but this technology is still immature. In the crystalline silicon (c-Si) value chain, Thirsk sees opportunities for optimizing mono-crystalline wafers with metal wrap technology and backside contacts; process optimization and material improvements would improve cell efficiency, and glass, wafer, backsheet, and grid improvements can enable more efficient light capture.

Looking ahead, Thirsk told the audience that while thin-film technologies will enjoy strong growth "and may be more attractive to value-add materials and equipment suppliers, thin-film cell production will remain a minority share for the medium term." (see Fig. 3, below) He closed his presentation encouraging the creation of a Moore's Law type of roadmap for the PV industry — one that delivers credible performance predictions based on technology and operational improvements.

Figure 3: Most likely PV market scenario. (Source: Linx Consulting)

SEMI's POV on PV

Bettina Weiss, senior director, PV North America, at SEMI, told SST, that the organization is in the process of signing a memorandum of understanding with SolarTech to give a voice to the equipment and materials segment, while also helping its members better understand other areas of the value chain, all the way up to utilities and installers. "Together with Underwriters Laboratories, for example, we will make sure we have a standards handshake at the module level," she said. "SEMI's scope ends with cell/module manufacturing and UL's scope starts at the final module level with compliance testing, etc., so that's a really good match."

Weiss also said that SEMI's membership has expressed strong strategic business interest in entering the PV market. "Our PV strategy is designed to address the entire PV manufacturing value chain that includes cell and module makers as potential SEMI member companies," explained Weiss. "That's new in a way — we want to attract the customers to join the organization to be closer to their suppliers, and more easily contribute to collective challenges facing the industry, e.g., in the areas of standards and public policy." 

Debra Vogler is a senior technical editor at Solid State Technology.

This article was originally published in Solid State Technology's WaferNews and was reprinted with permission.