[Amps] HV switch-mode power supply

[Roger]

Bill, W6WRT wrote:
> ORIGINAL MESSAGE:
>
> On Sat, 23 May 2009 08:55:21 -0700, "k7fm" <k7fm at 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generation without having to depend on a large and outdated power grid.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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