New Weather Station

[Wisdom Bear]

I got a $ 50.00 model from Wally world just to measure wind here.
I am in a 10 acre old pasture that now is my home for the motor home I live in.
I have Alabama Spark and Fizzle but want to build my own windmills for power.
Been here 6 months now. Power usage at the highest was average 50k watts per day at the coldest this winter.
(I use 2 1500 watt electric heaters) (Power hogs)
Average seems to be more like 20 k watts a day.

Average wind speed for today has been around 8 mph
Peak so far is 21 mph
Now I know that you would want a longer data report here but this seems normal for the time I have been here.
Will see more as time passes with the weather station.

From this (and I know you are just making a guess) what size mill could I turn basing on 48 volts?
Any good guess out there.
Also it is 11:30  am here and the norm is that the wind here will get faster through the day.

[Antero]

Wisdom Bear;

Thank you, for your interest in windpower.

If there is any aid for you; I have wrote about warming with windpower (translation) ;

http://translate.google.com/translate?hl=fi&sl=fi&tl=en&u=http%3A%2F%2Filmaisenergia.info%2Ffoorumi%2Findex.php%3Ftopic%3D268.0

In Finland we have no tarif for grid tie system, nor any tax / or anykindof support to small windpower.

But, we have now a huge interest to warm with windpower and allso to be off grid.
Second round is going on, when all the neighbours want windpower too  

Energy prices and demand to produce unpolluted energy; both are rising very fast  

Antero

[Wisdom Bear]

I'm not really interested in heating with wind power, but I did use the grid for heat this past winter. Will use something else next winter. Maybe go back to propane.

[fabricator]

My $0.02 worth, look into the prices of system components like charge controllers and inverters before you decide on your system voltage.

[Wisdom Bear]

I might be missing something here but I don't have a clue how these answers relate to my question?

[ghurd]

If the question is how big of a 48V wind mill can Xmph wind turn, then there is no answer.
The system (battery) voltage is not related to diameter or wind speed.
The wind mill should be designed to make '48V cut in RPM' at 6 or 8MPH, and the blades should match the power curve of the alternator.
G-

[Ungrounded Lightning Rod]

If the question is how big of a 48V wind mill can Xmph wind turn, then there is no answer.
The system (battery) voltage is not related to diameter or wind speed.
The wind mill should be designed to make '48V cut in RPM' at 6 or 8MPH, and the blades should match the power curve of the alternator.
G-

As Ghurd points out you can run any voltage you want.  Power is just the product of voltage and current.  Run at lower voltage, run at higher current for the same captured power.  A given mass of copper in a given magnetic, geometric, and cooling environment will capture the same amount of power whether it's in the form of a few heavy (or many-in-parallel) turns for low voltage at hight current, or many thin turns for high voltage at low current.

Battery (and transmission-line) voltage is only an issue because you have more resistive losses at higher currents - by a square law - for a given cross-section of wire.  Equipment gets 'way harder to find and more expensive for handling sustained currents over 100 amps, which leads to a rule-of-thumb of using 12V for systems running only up to a kilowatt peak load, 24V up to two kW, and 48V above that.  Above 48V nominal you leave the "low voltage" part of the electrical code (and start getting into "touch it and die" territory) , so hobbyists don't generally go above that unless they are after a LOT of power.

[WindriderNM]

you need to find out how much power you need in watt/hr or Kw/hr. volts X amps = watts, also the wind is stronger the higher your tower. sometimes the mill on my 65ft tower will be spinning fast and at the ground there is very little wind. there is a formula to calculate the power you can get from a mill. as i recall it is diameter^2 x wind speed^3 x 0.59
This is the max possible for a 100% efficient windmill.

[artv]

Hi All, Wisdombear sorry for the interruption, I was going to ask ,what the formula was ,and there it is.Windrider ,the only question now is what does that symbol mean (^)??.........thanks  .....artv

[rossw]

Hi All, Wisdombear sorry for the interruption, I was going to ask ,what the formula was ,and there it is.Windrider ,the only question now is what does that symbol mean (^)??.........thanks  .....artv

Thats  "to the power of".

2^3 is 2 cubed  (2 * 2 * 2)

That's a simplistic formulae however. Probably close enough.

A more complete/accurate version is:

        #    P = 0.5 x rho x A x V^3 * Cp * Nb
        #    where:
        #    P = power in watts (746 watts = 1 hp) (1,000 watts = 1 kilowatt)
        #    rho = air density (about 1.225 kg/m3 at sea level, less higher up)
        #    A = rotor swept area, exposed to the wind (m2)
        #    V = wind speed in meters/sec (20 mph = 9 m/s) (mph/2.24 = m/s)
        #    Cp = Coefficient of performance (.59 {Betz limit} is the maximum thoretically possible, .35 for a good design)
        #    Ng = generator efficiency (50% for car alternator, 80% or possibly more for a permanent magnet generator

[artv]

Ross........Thanks for clearing that up......artv

[Wisdom Bear]

NOW that is the answer to my question!
If I have 6 to 8 mph winds I can began to make watts, at what ever voltage.

Thank You

My daily average seems to be in that range.

[wooferhound]

2^3 is 2 cubed  (2 * 2 * 2)

This would normally be shown as 2³

[rossw]

2^3 is 2 cubed  (2 * 2 * 2)

This would normally be shown as 2³

In printed media, and hand-written stuff, sure I agree.

But in email, IRC and lots of "unformatted" medium,   x^y is the standard form to designate exponentation.
Not everyone can (or cares to) use superscripts - especially when there's an easier and accepted alternative

[fabricator]

I might be missing something here but I don't have a clue how these answers relate to my question?

My reply was meant to alert you to the fact that when you build an alternator for 48 volts your choices of inverters and most of the balance of system components is limited, especially with a higher output machine.

[zap]

especially when there's an easier and accepted alternative

"alt 0179" is "hard"?   ;)³

[Wisdom Bear]

fabricator, I was aware of that already.

Not trying to be a "smartass" but sometimes you guys that have all of this knowledge seem to over think the questions that you are asked.
I thank you and everyone else here for the help.
But remember that Most of us have not been as well schooled as some of you.
Doesn't mean that we are not as smart, just not in the same way.
We all can help each other.

Again, Thank You for replying.

[rossw]

My reply was meant to alert you to the fact that when you build an alternator for 48 volts your choices of inverters and most of the balance of system components is limited, especially with a higher output machine.

Don't take this as an invitation for world war three, but you're absolutely hell-bent against *ANYTHING* except your precious 12V squarewave.

*LIMITED* "choices of inverters and the balance of components" *especially with higher outputs*

In the *REAL* world, you will NOT FIND a commercial UPS running on anything less than 48V once they get over about 3KVA.
MANY of them run 96V or 120V or more.

As for general inverters only, I can't recall seeing many 12V inverters over a few KW. I can't remember seeing any in the 5KW and above range. I don't even want to think about the implications of 12V at 10KW and above. (over 1000 amps is going to be hell on batteries, connections, switches etc)

[rossw]

especially when there's an easier and accepted alternative

"alt 0179" is "hard"?   ;)³

Not to put too fine a point on it - but not every display will do superscripts. Not every keyboard does the "alt+n" thing, and not everyone uses winblowz.

[Wisdom Bear]

Thank U
I as many others here, I don't have a clue what "alt 0179" is hard" is.

This is what I am saying. Speak to us as "humans" not some geek that has spent his last 20/30 years in school!

Sorry but again I know a lot, maybe I could help U?

[rossw]

I as many others here, I don't have a clue what "alt 0179" is hard" is.

This is what I am saying. Speak to us as "humans" not some geek that has spent his last 20/30 years in school!

Sorry mate, the "alt 179" wasn't my post, I was just quoting it.

To answer your question about it, it was a reference going back to the formula early in this thread, where someone expressed a term a "something to the power 3", and had it written as   Y^3

I'd answered (artv) that that was  Y * Y * Y

The response from another poster was that you can get the little raised 3 (superscript 3) by holding down the "Alt" key, pressing 0179, then releasing the "Alt" key. It doesn't work in all operating systems, or all programs, or with all keyboards, but it works with enough that some people find it convenient.

I don't think anyone was suggesting you weren't smart. I know I  certainly didn't think it.

[Wisdom Bear]

Not talking about you. It just seems to me that most here talk OVER some of us head.
It doesn't take a 4 year college ed to know that we need help in this country.
But some here forget that or never knew that. Because they have ALL that schooling.

Slow down, some of us are trying to come up to speed.
And the dumbest of us may come up with something that the "ELITE" didn't see.

Just saying.

[zvizdic]

You need to say how much power you expecting,you are charging batteries or  direct heating?

48V and wind speed are not enough.

10' mill at 8 mph =+ - 50W

[Wisdom Bear]

zvizdic
Start at the beginning.
I told U what I have.

[zvizdic]

You think you do that is your problem.

[dbcollen]

Wisdom Bear,

You will get a much better set of answers from us if you ask better questions. Your generally abrasive demeanor will not elicit much desire in us to help you. Also remember we are giving you way more advice than you are paying for, a little respect goes a long way. If you want good advice for free, at least tell us exactly what you want to know, and what you are working with. I charge extra for my mind reading services.

Dustin

[Ungrounded Lightning Rod]

*LIMITED* "choices of inverters and the balance of components" *especially with higher outputs*

In the *REAL* world, you will NOT FIND a commercial UPS running on anything less than 48V once they get over about 3KVA.
MANY of them run 96V or 120V or more.

As for general inverters only, I can't recall seeing many 12V inverters over a few KW. I can't remember seeing any in the 5KW and above range. I don't even want to think about the implications of 12V at 10KW and above. (over 1000 amps is going to be hell on batteries, connections, switches etc)

You find higher voltages in higher power applications because the amount of copper you need for a given percentage of loss goes up with the square of the current and copper costs much bux.

Homebrew R.El systems tend to be designed to hold the nominal current at max power down to about 100A.  This is because electrical equipment for currents up to 100A is readily available while stuff for higher current is much harder to find and tends to the pricey.  So 12V systems tend to go only up to about 1 kW.  24V is just fine for up to 2kW  Voltages above 50V take you into a much more picky and expensive part of the electrical code so nominal 48V is about the top voltage  homebrew R.E.

[Flux]

An average wind speed of 8mph is really low. Not normally a good area for wind power but you can get something and it may be worth the effort but don't expect too much.

Normally 8mph is just about cut in speed and you will need quite a large machine to get 100W.

The power rises quickly with wind speed so on many days you will have winds over 12mph and may do quite well but with such a low average you will have lots of periods with wind below 8mph and you will get nothing. If you can manage without the heating then it can still be worthwhile but really the potential for heating is very limited on a poor wind site.

Someone else mentioned about 50W for a 10ft machine at 8mph, even this is probably on the high side but it gives you something to work from.

If you get those 8mph winds for many hours it's not so bad. here the wind comes after 10 in the morning and dies as the light fades in the evening and there are often periods of no production during the windy period.

Most machines have their rated power point over 25mph so your peak wind of 21mph would no be producing nominal power on most machines.

I didn't take part in the telephone pole debate but if you want to use one then a 10ft machine is about as big as you will want to go and if you get any wind above your 21mph you will need guy wires on it, it will rock all over the place.

Flux