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[Don Bowen <don.bowen AT earthlink.net>]

Panels will cost about $4 a Watt but that is not the end of it.  
Typically you will get full power only about 6 hours a sunny day.  
Batteries are another big expense, a good 6V 220 Amp hour or Ah battery 
is over $100 and each bank requires two.

Throwing numbers around.  For sake of comparison the wall outlet where 
you have you computer, desk lamp, cell phone charger, CD player, plugged 
in is typically rated for 15 Amps.  15 Amps at 120VAC is 1800 Watts.

The first purchase for any AE thoughts is a Kill A Watt. 
http://www.amazon.com/P3-International-P4400-Electricity-Monitor/dp/B00009MDBU/ref=sr_1_1?ie=UTF8&s=electronics&qid=1265315149&sr=8-1

That will help you understand you power needs and help cut back where 
possible.  It is one of the best AE investments you can make.  I 
currently have mine loaned out.

Lets say you need 1000 Watts most of a day for computer, lights, music, 
whatever.  You go to various sources and find out that you can expect 
about 1/4 of the days to be overcast and not generate power and that the 
number of such days in a row is 2.  That is one day of 4 you cannot 
generate power and that you have to last 2 days before recharging.  
These are made up numbers and vary by location.  There are several 
sources for such information based on your location and weather.

1000 Watts for 24 hours is 24,000 Watt hours or Wh.  The above mentioned 
220 Ah battery bank is about 2600 Wh.  You need ten banks or 20 
batteries for around $2000.  There are cheaper larger capacity batteries 
but those are what I have.  Oops I forgot, you need 2 days worth.

You have to generate five days worth of power in 3 days at six hours a 
day.  You will need about 3000 Watts worth of panels at roughly $10,000.

All this just to duplicate the power available from one wall outlet.

--
Don Bowen           KI6DIU
http://www.braingarage.com/Dons/Travels/journal/Journal.html