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Figuring Output from a Given Surface Area - Page 3

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Posted by Eeyore on August 8, 2009, 6:50 pm

Mauried wrote:

PEAK watt which I doubt the OP understands. I.e. the amount of power produced at
mid-day when the sun is most favourably

Indeed but they want to keep the hype going.


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Posted by frigitar on August 8, 2009, 10:50 am










          5,631,108 $13,148.35   /y=

Hey Tom,

Its a little difficult to figure out your calculations here... Im
pretty sure you should get back your investment cost (especially since
you assume 1$/W !!)
could you send across the excel file perhaps?

I'll have a look and let you know. There must be some little thing
you've overlooked or miscalculated.


Posted by Eeyore on August 8, 2009, 6:47 pm

Tmort wrote:

And the much less efficient than silcon wafer types ( about 7.5% vs 15% ).

Then they are a bunch of outright liars. I'll have to peruse your figures more
carefully. Where do you propse to locate these
panels geographically ? It makes a HUGE difference if it's in Nevada / Arizona
or Alaska for reasons that I hope are obvious to


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Posted by Ron Rosenfeld on August 9, 2009, 12:05 pm

I think your calculations are reasonable.  I get slightly different
results, but in the same ballpark, so far as electric generation is

I'm not sure how valid your assumptions are, as I don't know if Nanosolar
is actually delivering product that meets their undisclosed specifications.
I see at their web site that some product is available to large scale
purchasers, but they are still retaining their data sheet as proprietary.

Accordingly, I was unable to correct for temperature, nor do I know how
they rated their panels.  I just used the 142.9 watts for a panel 1.6*0.8
meters to make the calculations.

It does appear as if you are subtracting installation costs for every year,
rather than adding it to the initial cost.  And I couldn't begin to guess
at installation costs for a project of that size.

You also don't indicate what you are using for a discount rate in computing
the payback time.

But that is quibbling.  The facts are that you show that you have access to
inexpensive grid-power, and that makes a great deal of difference. You're
also not in an ideal location for solar power, which makes some difference.

Around here, grid-power is closer to $.155/kWh which, even with a 5%
discount rate, would yield a payback time of closer to 5 years.

With your electric rates, and a 5% discount rate, the payback time is
closer to 24 years, assuming your rates stay the same, and these new style
modules hold up for that length of time.

One thing you didn't figure in (nor did I), but you should with this size
project, is annual deterioration in output.  If at 20 years the modules are
only putting out 90% of their rating, that would prolong the payback time.
You'd need to check the data sheet to determine that.

Posted by Eeyore on August 12, 2009, 10:31 pm

Ron Rosenfeld wrote:

How can you get similar figures without knowing the location of the panels,
their orientation and the resulting insolation ?

Nanosolar only claim 75 peak watts for a 1 m2 panel, which translates to 96
peak W for a panel of that size.


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