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What Size Turbine do I
Just a few easy steps to figure it out
about how much of your existing electrical consumption and $$ billing you would like to replace with “free”
electricity from your Wind Turbine.
1/3, ½, all of it? Since your Wind Turbine is
a long term investment, think a little “long term” about the future cost of electricity. If you decide to
replace ½ of your consumption and the price of electricity doubles ,,,,,,, your billing $$ will be what
it is now, in addition to the cost of the turbine.
Gather up the last 12 months
electric bills. It doesn’t matter what the dates are as
long as there’s a 1 one year group so that it covers all the seasonal variations.
Fill out a chart with the
numbers from your utility bills- as shown on the example
chart below. (just take a blank sheet and write down the headings)
Total up the columns: #Days,
KW used, $$. Divide the KW used total by the # Days
total. That will give you an average KW usage per day. Then divide the KW per day figure
by 24. THIS WILL BE THE AVERAGE KW per
HOUR usage you need to make with your Wind Turbine to replace 100% your
Once you know your average KW usage per
hour. It’s easy to select a turbine because they are rated in maximum KW per HOUR. !!!! There is
one little catch in this. The wind doesn’t always blow at the correct speed to run the wind turbine at maximum
rated capacity. Sometimes it doesn’t blow at all. So you need a “fudge factor”. A general easy rule is to use 33%
or 1/3 of rated capacity for wind turbine production.
The simple way to do this is just
take your AVG HOUR KW times 3.
So, as in the example below - The AVG 1
HOUR KW useage is 5.3k , times 3 = 15.9KW. Therefore a 15KW turbine roughly should do the job of
replacing 100% of our current usage. If you only want to replace ½ of your purchased power, then a 7.5kw could
A on "site"wind study over a year would
give you a more exact “fudge factor”. But who’s to say whether that year was “more or less” windy than the
previous. So, you must sometimes just make a best judgement. If you have concerns then go one size larger on
the turbine for your intial install or consider adding a solar panel supplement at a later
Here is a typical 30 year old, 2 story, 3 Bedroom, 2
Bath, that is ALL ELECTRIC
(Furnace + AC). Its heated on on 3 levels with electric resistance
heat. (3600 sq ft total) Below
is a chart of the actual electric power comsumption for 2009.
47710 KW used, divided by 378 days =
126.21 KW per day. Divide by 24 hours = 5.26 KW per
Another useful number from this chart is to divide the annual $$ by 12 to get a monthly amount. In
this example the average monthly amount is $ 2240.79/12 months
= $ 186.73 per month.
This is useful $$ amount to know when you get to the point of calculating payback/loan
( It should be
noted that this house has a 2 tier/time of year rate and as such the $$ amounts don’t seem to match the up/downs of
kilowatt usage. That’s why it’s important to get a year’s data and then average to the monthly
For more information, visit www.iowawindturbines.com
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