Ron Kean wrote:
> On Mon, 14 Jun 1999 09:49:27 -0400 "Michael S. Lorrey" <mike@lorrey.com>
> writes:
>
> >Ron Kean wrote:
> >> That must be $0.12-0.25 per watt, rather than per kwh?
> >>
>
> >No. Per kwh. The last I heard on this was in 1995. It was a joint
> >development project between US Solar Corp, the Energy Department, and
> another
> >solar company, to develop the manufacturing process and some test bed
> structures.>--
>
> If a small panel produces 20 watts in full sun, and has a wholesale price
> of $5.00, then the panel could be said to cost $0.25 per watt of
> electrical power output in full sun. But if the panel is described as
> costing $0.25 per kwh, what sort of analysis would be used to arrive at
> that expression of cost, assuming the selling price of the panel and its
> electrical ratings are known?
You need to amortize the intitial investment in the panel, as well as incidental expenses to install and wire up the panels, over the period of use, involving your discount rate, the inflation rate, etc... You need to use this discounting method in order to properly compare it with a pay-as-you-go grid based service.
I used to do the reverse with the exit sign retrofit kit I developed, to show that the rate of return on investment was so high they'd have to have had stock in Microsoft to get a better return.
Essentially, you figure out your own discount rate, then you subtract inflation
for that year from your discount rate for that year to get your adjusted
discount rate, plus you need to discount the cell output degradation. Here's an
example:
Solar panels: 1000 watts total peak
So thats how it works.
Hours of operation per annum: 4000 hours
Avg. output: 500 watts.
Total annual output: 2 million watthours or 2000 kwh per annum*
*(this is intitial, estimate cell output degradation of 5% per annum)
Period of use: 10 years.
Cost of panels and installation: $5000.00
Personal Discount Rate: 6.5%
Inflation rate: 1.5%
Adjusted Discount Rate: 5%
Year Output(kwh) Discounted output (kwh)
1 2000 1900
2 1900 1805
3 1805 1715
4 1715 1629
5 1629 1548
6 1548 1471
7 1471 1396
8 1396 1316
9 1316 1251
10 1251 1188
Total discounted output: 15219 kwh
Discounted cost per kwh: $0.329
--
TANSTAAFL!!!
Michael S. Lorrey
Owner, Lorrey Systems
http://www.lorrey.com
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