News
Improving solar efficiency by coating cells

July 23, 2008 – Australian solar energy start-up Xerocoat has invented new
antireflective coating that it is says can improve power output across
all solar energy technologies, from traditional silicon wafers to thin
film and solar thermal.

July 23, 2008 – Australian solar energy start-up Xerocoat has invented new
antireflective coating that it is says can improve power output across
all solar energy technologies, from traditional silicon wafers to thin
film and solar thermal.

The idea is simple: most solar cells are covered by glass and glass
reflects light. Reflected light reduces the light available to make
electricity.

By coating the solar cells, the glass reflection decreases by 3
per cent at noon, and by 6 per cent in the morning and afternoon, according to
the company. This increases the light absorption by the cell, and thus
power output by 3 per cent on a peak watt basis, and 4 per cent on
kilowatt hour basis, Xerocoat says.

That would be equivalent to increasing the cell efficiency by 0.5
per cent to 0.75 per cent. On a 100-megawatt solar thermal plant this
might hike annual profits by $4.5 million to $8.5 million (not counting
the cost of the coating, that is), according to the company.

Xerocoat was founded by Australian Michael Harvey, a Ph.D. in
materials and optics for lasers, who one day stumbled across the
antireflective optical effect in the lab. After more research, funding
from the University of Brisbane, and eventually VC backing in 2007 by
NTH Power and Southerncross venture partners, Harvey opened up
Xerocoat's office in Redwood City, Calif., in April.

The antireflective coating is made by single-layer porous silicon
oxide, less than 100 nanometers thick. It meets the industry standard
durability test IEC 61215 for crystalline silicon modules, according to
the company.

The initial venture capital of $6.8 million allowed Xerocoat to
build a pilot line, which it says it will use for its first,
undisclosed customer in August. Right now, it is raising a B-round of
funding of about $50 million–money that will be used for building a
production line. Xerocoat hopes to start large-scale manufacturing by
the end of 2009.

CEO Tom Hood admits he isn't alone in the coating space, among the
at least five competitors is Germany's Centrosolar and Danish Sunarc
Technologies.

But Hood points out that less than 5 percent of the photovoltaic
industry uses antireflective coating today, in a market he estimates
will be worth $1 billion in five years.