Gorilla glass for PV panels?

The Associated Press reported this week that Corning is
ramping up production of one of their long dormant
products, "gorilla glass." They invented this in 1962,
and it has been slowly but surely finding its way into
applications that require high impact resistance, such
as cell phones. Corning is investing $180M in a new
production facility in Kentucky, among other things.

The interesting thing about gorilla glass is that it is
2-3X harder than regular glass...at half the thickness.
Gorilla glass is in effect tempered during its unique
manufacturing process.

If you think about it, this has multiple implications
for solar. While the efficiency of the solar cell has
been plodding along, if you can make an improvement
in the glass that is layered on top of the cells, you
can get a bump right now without having to depend
on the laborious R&D on cell efficiency itself.

So the obvious is that if the glass can be made half
as thick, and assuming gorilla glass has the same
transparency properties as regular tempered glass,
then it should pass through additional light to the
underlying cells. More light, more energy harvest.

Here is my guestimate at this effect. Ordinary
glass absorbs about 10% of the incident light. Let's
assume that with half the thickness, you get half
the absorption, or 5%. This would yield on the
order of 1% higher panel efficiency given that current
panel efficiencies are in the just-under 20% range.

[1% to the end customer isn't that much, but on a
percentage basis for the underlying technology, it's
a year or two advancement. 1% for thin-film is a
10% boost over its current 10% efficiency, and is 6%
boost over current best mono-crystal efficiency.]

As we know, heat reduces cell efficiency. I understand
that the rule is you lose .5% per 1 degree C above 25
degrees C. Since glass holds heat, half the glass, half
the heat. I don't know how to quantify the end effect
of this reduced heat, though.

A big practical benefit would be in reducing shipping
costs, from manufacturer to distributor to solar
installer. My Sharp 235's weighed in at 44 lbs each.
If the glass were half as thick, maybe that cuts the
weight by a 25-35%?

If glass is sold by the pound, and Corning doesn't
charge too much of a premium, theoretically the
raw material glass cost could drop by up to half.
One industry analyst estimated that Corning would
charge an extra $30-60 per "set" (he didn't define
what a set is). With the additional production
capacity, though, any premium will start to diminish
as time goes by.

The extra hardness might also reduce losses
attributable to hail (and the occasional errant golf
ball!).

Anyways, one article mentions some of the solar
implications:

Gorilla glass is an ultra-strong glass that Corning invented in 1962. The glass, which is scratch resistant, is used in more than 200 different mobile devices. There are plans for it to be used for about 100 others.

The investment in the Kentucky plant will also build capacity to begin to produce specialty glass for thin-film photovoltaics used in solar energy conversion.

"Thin-film photovoltaic technology is a rapidly advancing solution within the fast-growing solar energy industry and plays to Corning's strengths in flat glass, materials science and light management," said Gary Calabrese, vice president of science and technology and director for Photovoltaic Glass Technologies.

--

John