This article first appeared in Solar Today
by Mike Koshmrl
With 1000 "little cuts", SunShot aims to drop solar costs 75% in less than 10 years.
It's easy to be skeptical about the Dept of Energy's (DOE) SunShot Initiative. The goal, installing utility-scale solar at $1 per watt by 2020, would bring solar costs down to 6 cents per kilowatt-hour (kWh), roughly the cost of coal-fired electricity.
The name, SunShot, is a play on President Kennedy's 1961 pledge to land a man on the moon by the end of the decade. DOE Secretary Chu announced the $27 million program in February, the funds for which will be spread among nine companies. How can $27 million make such a big impact?
To achieve $1 per watt, the solar industry needs to streamline in a big way. It will need considerable module efficiency gains and slashed costs for installation, operations and maintenance and all other system components. Photovoltaic (PV) modules will need to come down 70%, inverters 55% and construction-related costs nearly 75%.
"We'll get there," says Frank van Mierlo, CEO of SunShot grant recipient
1366 Technologies. "Look at the historical cost curve of solar. The production costs come down 10% every year."
At 1366, van Mierlo and fellow co-founder Emanual Sachs are working to commercialize a method for manufacturing crystalline silicon wafers that halves the need for hyper-pure silicon. The process, which virtually eliminates silicon waste (about 50% is currently lost), sets the stage for a dramatic wafer price drop. "If the total installed cost is going to be $1, that means wafer costs have to come down to about $0.25, from $1 today.," says van Mierlo. "And I think it's extremely doable. We're just one of many companies working on this, and our technology alone will take one of the largest cost components and slash production costs by a factor of three - at least."
Here's a closer look at what four of the SunShot grant recipients are doing to help achieve these results.
PPG Industries
Target: Thin-Film Efficiency, Durability
Thin-film PV technology has its advantages - it's lightweight, production is relatively cheap and simple, and it's not silicon-dependent.
Durability, however is a disadvantage right now. Until nanotech companies make headway on a durable, exposed cell, commercial thin-film modules will continue to require robust encapsulants.
As First Solar and other thin-film manufacturers began to ramp up, that need caught the attention of
PPG Industries, a Pittsburgh-based glass and glass-coating maker with roots in the 19
th century. PPG's contribution actually predates the industry: Back in the 1930s, the company pioneered the first low-iron glass. Now, backed by $3.1 million in SunShot funding, PPG is working to perfect a glass encapsulant for modules made with cadmium telluride (CdTe) - the most advanced thin-film technology in mass production.
PPG will try to maximize CdTe module efficiency by pulling three innovations onto their high transmission glass. "About 4.5% of the sun's energy is lost on the outside of the module," says Jim McCamy, PPG's manager of solar technology. "By reducing losses from reflectivity, we're increasing the number of watts. By creating better conductive layers, we improve the number of watts."
The new encapsulants, still unnamed, will separate the first layer of CdTe from the underlying transparent conducting oxide (TCO) glass substrate with a buffer layer. A third component, an anti-reflective coating, will be applied to the module front side over the TCO glass. "These technologies exist, but they've never been combined," McCamy says. Research is taking place at PPG's research center outside Pittsburgh, at Colorado State University (whose research formed the basis for Abound Solar's CdTe technology), and at Oak Ridge National Lab in Tennessee.
During a 2009 First Solar conference, glass was named as the CdTe industry's single largest cost component. Two years later, CdTe is providing the best value proposition for utility-scale PV developers.
