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http://www.igreenbuild.com/_coreModules/content/contentDisplay_ Whats Holding the Solar Industry Back?

By: Jon Dougal - Monday, December 10, 2007

Source: Various Sources


Back in the 60s or 70s (too long to remember exactly) there was this myth that if the Pentagon would cover all their facilities
with PV the price would drop enough that the average citizen could cover their dwelling unit. The simple answer to this
question is of course price. The not so simple answer is thinness.

While California has 73% of the U.S. solar market is it price or efficiency holding back exponential growth. Efficiency means
packing more silicon wafers into each cell. How can you do that? There is another issue, that of brittleness of the wafers. The
thinner they get the harder it is to connect the poles to the edges of the wafer.

The growing technology in Lasers seems to answer both the efficiency issue and the resultant cost issue. So what do lasers
have to do with photovoltaic cells? Lasers which are used in eye surgery are so programmable that they can slice silicon much
thinner and then they can make the polar connections without human intervention. So more wafers can be packed into a
single cell, making it more efficient.

No human contact means less waste, again lower costs. Older human contact wasted 1 wafer in 10. Semi conductors
manufacture at 99%, very little waste.

The shadow that the contacts (poles) cast over the lower wafers in the stack also contribute to in-efficiency. With this new
technology developed by Coherent Inc., that shadow is reduced and the subsequent efficiency is raised from almost
5%.

5 Years ago the solar industry was given a re-kick-start by Germany. Germans introduced the Feed-in Tariff concept. This
tariff is a way to incentivize solar installations, and Germans endorsed the concept immediately. Germany is paying
approximately 20% over market just to get enough solar to meet demand.

Germany subsidizes installation by paying a rate for generation lower than they sell it for. Every installation is connected to
the national grid. Many states in the U.S. only offer a rebate against the energy bill. Colorado just introduced legislation to
pay a home generator at the end of the year for their net non-used energy.

Quick factoids on how solar cells can be improved when made with lasers:
- Typical solar cell efficiency is about 15% - using a variety of laser applications can improve this to around 20%.
- In the average household installation (consisting of 15 solar panels), solar cells made with lasers can save around $4 per W.

- Since lasers are non-contact applications, production yields will improve from about 85% to over 90%, which will decrease
costs to the tune of about $1000 per panel!

Coherent Inc, headquartered in Santa Clara, California is the worlds largest laser manufacturer in the world. Their involved in
solar production applications, green initiatives like ozone monitoring, display technologies, materials processing, medical and
surgical tools and many other applications.
http://www.coherentinc.com



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Lasers increase Pv manufacturing efficiency
12/12/2007
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