[Greenbuilding] Solar electric configuration details

[William Revelle]

Lawrence,

In your calculations, don't forget the strong seasonal effects on PV 
generation as well as consumption. That 5 hours a day figure is an 
average over the year.

The most efficient air conditioner is one that is not turned on! 
High efficiency ceiling fans do a good job for many days of summer.

We have a nominal 6400 watt system that produces between 4 to 34 
KWH/day depending upon the season and the weather.   Total production 
for the year (we live in Evanston, just north of Chicago so we have a 
bit less sun than St.Louis) runs about 5700 KWH or 80% of our total 
electrical consumption.

I use the data that I have recorded over the last 3 years to 
demonstrate graphical data analysis on a page discussing the use of 
the R stats program in analyzing data.

http://personality-project.org/r/r.plottingdates.html

Ignore the R code on the page and just look at the graphs.  I show 
daily data (the individual dots) as well as various smooths of the 
data.  What is clear is that production is very seasonal as is 
consumption.

You might want to visit a discussion of  our production/consumption 
at http://revelle.net/lakeside/lakeside.new/electric.html

Is it economical? No. (Even with a $6/watt subsidy from the state for the PV).
Does it reduce our carbon footprint substantially?  Yes.
Does it make other people want to reduce their electrical consumption? Yes.
Does it make other people want to reduce their carbon production? Yes.

Good luck.

Bill





At 5:34 PM -0600 11/9/06, Lawrence Lile wrote:
>  >Is there nothing you can do to reduce that 34 kWh a day?  The return on
>
>investment (to say nothing of payback) on CFL bulbs is 300% (before
>taxes).
>
>The 34KWH/Dy is a wild guess estimate, based roughly on my current
>house, from my memory which is fulla holes.  The new house should be
>dramatically more efficient, it is set up for 100% fluorescent lights,
>super efficiency AC, radiant heat not requiring a juice-sucking fan
>motor, no electric appliances, and so on.  After a month or two I'll be
>able to gauge my electric usage more closely, hopefully it will beat the
>current house by at least 40%.  I move in December. 
>
>CFL bulbs are great compared to incandescants.  They are wimpy compared
>to high efficiency T-8 bulbs with good electronic ballasts.  The 4 foot
>T-8 lamps can beat a CFL lamp by another 50%!  I'm using a lot of T-8's
>in the new house. 
>
>Back to the solar electric system:  I'm trying to figure out if this is
>just nuts.  So far, I can't justify it on economics, Carbon, or anything
>except reliable power and the Solar Grin I'd get driving up to my house
>and seeing the solar electric panels on top of it. 
>
>--Lawrence
>
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-- 
William Revelle			http://revelle.net/revelle.html
2815 Lakeside Court
Evanston, Illinois
Information on energy efficient houses 
http://revelle.net/lakeside/energy.html