Bill, W6WRT wrote:
> ORIGINAL MESSAGE:
>
> On Sat, 23 May 2009 08:55:21 -0700, "k7fm" <k7fm@teleport.com> wrote:
>
>
>> I just figured my power is costing me 2 cents per kwh.
>>
I assume that is real costs with the purchase and installation amortized
over 20 years or so? In the SW you should see a payback of 10 to 15
years. Less than 10 in some locations. In Michigan we aren't even on the
map for payback times.
> <snip>
>
> REPLY:
>
> That is impressive, but IMO, it needs to be done by the utilities, not
> by each homeowner. Barring some technological breakthrough, they have
> an economy of scale that we individuals can not match at present.
>
>
And that scale will eventually make it cheaper for distributed
generation without having to depend on a large and outdated power grid.
We started out as the technology leader in these fields but are now a
long way behind both Germany and Japan. Germany's power generation is
an example of where we could have been had the renewable energy bills
not been killed back in the 80's. They are already past at what we are
arguing over for goals in the next 10-20 years and they did it without
subsidies. IOW they are already using 20% of renewable energy for power
and the home owner is paid a premium for any excess they sell back to
the grid. Here? We get wholesale.
> To be more specific, I am puzzled why, after all these years, solar
> cells are still so expensive. By now they should be as cheap as the
> sand they are made from.
>
Silicon prices have dropped dramatically . The world's largest producer
of poly crystal Silicon has doubled their capacity twice is the past few
years and are spending over 1.2 Billion dollars to double that scale
again as well as building a second plant down in Tennessee.
However, the amount used in a solar cell is huge compared to other
devices. Nearly all devices using a Silicon substrate are
made/created/grown on Silicon wafers. These wafers are now some where
in the neighborhood of 14" in diameter, but the loss in making wafers
alone is on the order of 50%. Then there is the yield of devices you can
get from a round wafter. You can get thousands of transistors and
hundreds of microprocessors, but only 6 or 8 solar cells and that is if
they are all good. Add to that the materials and labor needed to
combine the cell into a working device and that into a working panel it
does become expensive. Add to that the demand for pure Silicon that
drives the price of the raw Silicon.
The price of Silicon has dropped dramatically over the years. I
remember when those wafers were only 3/4" in diameter and intrinsically
pure Silicon sold for $165 USD a gram in the early 60's. Now the poly
out of the reactors is more pure than the best multi pass, float zoned
single crystal we could make in those days and sells for some where
around $4 to $6 USD a Kilo and has remained around that price for
several decades. We went from 3/4" poly rods 16" long to huge rods that
take chain falls to lift them out of the reactors.
Back in the late 60's or there abouts we developed a method of sawing
wafers that cut the waste by a bit more than half. That one operation
doubled the available Silicon which dropped the price to the point where
some suppliers went out of the business. Now we see suppliers doubling
and re doubling capacity and still not meeting the demand. Then there is
conservation. We went from a large tank farm of liquid H2 with
deliveries every day or two to one tank. I have no idea as to the
present requirements for deliveries, but at one time only NASA used more
liquid H2 than we did.
But by the time that sand gets turned into solar cells that are
assembled into panels that can gives us useful power for remote sites
there are many operations and materials that contribute to keeping the
cost of those panels high.
Once the entire operation becomes automated and/or alternatives such as
thin film solar cells are developed we may see some substantial
reductions in price.
Actually they have come down substantially. I was given a price of
$50,000 for a system that would essentially power my whole house which
is far less than just a decade ago. Unfortunately in Michigan we do not
receive any subsidies although there is a federal tax credit.
73
Roger (K8RI)
> 73, Bill W6WRT
>
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