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The subsidiary of Energy Conversion Devices, Uni-Solar, has detailed its technology roadmap, which is intended to push conversion efficiencies to 12% and a cost-per-watt of 95 cents by 2012. Importantly, the efficiency gains and cost reductions come from material improvements and process optimizations rather than fundamental cell changes, which should ensure a smooth demand driven production ramp in 2011. Initially, Uni-Solar is targeting area conversion efficiency gains to 8.2% in 2010 and by close of 2011 calendar year approximately 10%, with fully loaded production cost-per-watt of US$1.50.
“We are continuing to develop our technology by focusing on improving our conversion efficiency to 12% and beyond,” commented Mark Morelli, president and CEO of Uni-Solar’s parent company, Energy Conversion Devices. “We have demonstrated that our core technology is capable of conversion efficiency of 15.4% in the lab, and we are now focused on translating those results into commercial production volumes at 12% and ultimately improving the conversion efficiency to 20%-plus.”
Key process development has centred initially on improved light trapping using a significantly improved back-reflector layer, according to Subhendu Guha, executive VP of PV technology at ECD and chairman of United Solar Ovonic.
Speaking with PV-Tech, Guha also noted that an altogether superior a-Si/germanium alloy has been employed, which captures red light more effectively. A proprietary plasma CVD process not only doubles throughput but also offers greater deposition uniformity over a larger area, which in turn has enabled the cell surface area to be expanded on its standard laminate size, further boosting surface area efficiencies from the longstanding 6.7%.
Several important knock-on effects mean that Uni-Solar gains in a reduced cost-per-watt and capex-per-watt going forward. The upgraded CVD tools are expected to cost between US$15 and US$20 million, while boosting capacity by approximately 30MW.
Guha also noted that as the performance and manufacturing throughput gains are not a result of more complex processing, a target of 95 cents per watt with 12% efficiencies with continuous yield improvements, similar to those already achieved, was realistic in a high-volume, high-utilization environment.
The improved light absorption doesn’t involve light-induced degradation, creating robust efficiency gains as well as stability.
However, after a year of falling fab utilization as demand waned, Morelli explained in a conference call to discuss the roadmap developments that this would be a demand-driven ramp. He cited an expanding commercial rooftop market when efficiency and cost reductions kick in in 2011, highlighting that the low-bearing commercial rooftop sector should have a commercial size of 3.3GW by 2013 and that the residential market using specially designed tiles has a market potential of 3.2GW in Europe and nearly 1GW in North America.
Financial analysts noted in the call that the cost-per-watt claims were still higher than the likes of First Solar, which is already below US$1/watt. Morelli highlighted that its core commercial rooftop market of load-bearing roofs could not be served by heavier glass-based thin-film modules and that its simpler installation significantly cut install costs, making Uni-Solar technology highly competitive on system price and LCOE.
