Increase in height will help a lot. I think the bit about low mass blades is a lot of nonsense, I would stick to conventional blades and not mess about with other constructions other than wood.

Most of your energy is in very low wind so this indicates an axial machine with best efficiency in low winds.

You also need to find out the cost of getting the grid connected. Then stop mucking around and dive in with both feet, and go off-grid 100%. I think you'll find you can build a pretty substantial RE system for the cost of installing several hundred feet of grid.

0.00508 x Area x windspeed^3 x efficiency

area in square feet, windspeed in mph, and efficiency about 0.35

10 foot rotor and 8mph avg speed means about 28.6 Watts or 0.686 kwh per day.

At 26 mph wind on average it would be 1000 watts avg or 24 kwh per day.

For a good RE home only using 5 kwh/day or 208 w/hr you would need 15.5 mph avg wind speed.

If you wanted to get 5 kwh/day from that avg windspeed of 8mph(best case) it would take a 73 foot rotor.  Or about 7 windmills, each with 10 foot blades.

-----

Spelljammer

P = (.5)(1.22)(PI)(Radius^2)(V^3)(efficiency)

Radius and velocity are in Meters.  
Efficiency I assumed 30%

I condensed this and converted for feet and miles per hour.

****************************************************
     P = (0.00477)(R^2)(V^3) <==== use this formula ****************************************************

R = radius in feet
V = wind velocity in mph

so for 10 foot rotor and 8 mph wind...

P = (0.00477)(25)(512)

Power = 61 watts

** NOTE - if you don't want to use 30% as the efficiency, then take the 0.00477 and divide by .3 then multiply by the new efficiency.
Example - for 40% eff... (0.00477 / .3)(.4) = 0.00636

(A 12 foot turbine would be 88 watts at that wind.)
(A 14 foot turbine would be 120 watts at that wind.)

If you are shooting for about 5 kwh/day then having two 10 footers would not quite make it.  It would be 2.928 kwh.

But having two 12 footers would average 4.2 kwh/day, which is pretty close.
And having two 14 footers would average 5.76 kwh/day.

I say, build two 12 footers on a double tower shaped like an "H".  Or just build 2 towers and put them where you will.  That would give you close to a goal of 5 kwh/day.  And add a couple of solar panels just for good measure.  Like two 120 watts and 6 hours of insolation per day would be 1.44 kwh/day

Hopefully, that situation doesn't look as bleak.

-----

Spelljammer

Some people use diameter ^2 and then multiply by a coeff...something like .78.  My formula is just like the original but it converts to metric so that you can use feet and mph instead of metric.  In other words, the conversion is "built in".

Amanda, good point.  I didn't think of putting solar panels on the "H" tower.  They could be placed in a line across the cross beam.  If the two legs of the tower are 15 feet apart, then that leaves a 3 foot gap or more between the two 12 foot blades so they can't hit each other.  And that would mean about 7 solar panels mounted.  At 120 watts each that would be 840 watts. (I always mention 120 watts because that is what I have now.  3 of them.)  You could also have a double cross beam and get 14 solar panels.  Although strong winds would be a issue with that much surface area.

Good point, Craig.  I've got some golf cart batteries now.  I'm in the process of getting some forklift batteries though.  They will be used but I've got a pulser to desulfate them.  I've tested the pulser on some old car batteries.  One was at 2.4 volts, one was at 9.8 volts and the other was at 10.2 volts.  It took between 2 and 4 days each to fix.  I had two others I tried, but couldn't get them to work.   The pulser is made by Donald Denhardt.  http://www.shaka.com/~kalepa/desulfparts2.htm

The only reason that one at 2.4 volts worked is because it shot up to 16 volts when I put the charger on it...wouldn't hold a charge though.  After a day it dropped down to 12.0 volts and over the next three days came up to 14.3.  I load tested them all and get about 40 - 50 ah.

So, I'm blown away by this device.  Anyway, I'm getting some forklift batteries and will share with a friend down the street.  All together we are getting 2x 12 volts(700 lbs each), 2 x 24 volts (about 500 lbs each), 1 x 36 volt ( 4,000 lbs).  All that paid for and delivered for $250( the two 24 volters I have to pick up myself).  They are used but in decent condition and can't beat the price.

The trick is to call some forklift places in your area that sell new batteries.  They normally have someone come out and pick up the old batteries for scrap and they are paid 3-5 cents per pound.  The owner will usually sell you a few at the pound rate and will even deliver them for about $50 to $100.

Anyway, gotta run...heading to Home Depot.  :)

---

Spelljammer

Spelljammer