8ft Power Expectations

[Yianie123.]

Hello everyone,  I will be building an 8ft diameter wind mill soon.  I have been doing a lot of research and there seems to be a variety of design opinions, number of magnets, wire size and rotations.  Well, I would like to know how much power I should be expecting from an 8ft diameter at a wind speed of 5, 10, 15, and 20 mph.  Any help will be greatly appreciated.  John

[SparWeb]

Sounds like you could be building one from Hugh Piggott's recipie books.
From his website, here's what he suggests are reasonable expectations:



You should read the rest, from his website:

http://www.scoraigwind.com/axialplans/index.htm


Ha listen to me I sound like a shill - I am in no way affiliated with Scoraigwind, nor am I on Hugh's overly generous payroll.
(I'm holding out for the fat bonuses that the Fieldlines guys get)

[Yianie123.]

I am familiar with this chart.  I was wondering about the power of PMA's.  Do they really get the power that they claim or is it just advertising?
John

[Seekscore]

Check your e-mail.

Mike

[Flux]

Are you really talking about a Hugh piggott type turbine which does really do what it claims or you trying to use some hyped up heap of crap from hydrogen Appliances or something.

You can easily predict what a given diameter decent wind turbine can produce in a given wind but if you are looking at independent PMAs then what the alternator can do, what it is claimed to be able to do and what you can get out of it on a turbine of your own manufacture are very different questions.

If you buy some PMA at random and fit it with some blades that you fancy without understanding the whole train of events you will probably end up with very little or nothing.

Flux

[sk windpirate]

Hi John

You have a excellent point.
Many company's are making claims that are in the unbelievable range, unheard of returns, And can power a house hold
Save you hundreds.

That is why this site is so popular. here the numbers are real. If you were to build one of Hughes mills, AND "build it to the book"
then the claims will be real.

Ron

[SparWeb]

Yiannie,

Your faith in the Piggott machine, or any other, will lie on your trust of the source of information.  Better research leads to better data and that increases trust.  At some point you are either satisfied or not, and make your choice.

Forgotten so far is the value of the "mean wind speed".  Do you know this in your area?  You probably know that it is affected bythe height of the tower, obstacles nearby, and so on.  A bad site will ruin a perfectly good wind turbine, so even the best machine does not hide all problems.  Who can promise you anything when so much could go wrong?

In DIY form, the kit is offered to you as a "recipie".  It is up to you to break the eggs, mix the batter, and set the oven at the right temperature, so to speak.

We still wish you luck, and offer you help as you need it. 

[Flux]

This is good advice. Few people have even a vague idea of their true wind speed. Local conditions may make some sites useless.

If you are looking for general advice as to what a decent 8ft machine can do on a good site I would say that if it is your only source of power and you live carefully a good 8ft machine on an half decent site can be very useful indeed. On a poor site it may be little use.

If you are not dependent on wind power and have the grid then probably best consider it a hobby. It is unlikely to pay for itself and the expensive inverters in a realistic time unless you are really careful with power use.

I would only ever consider grid tie of such a small machine on a first class site with average wind speed over 12mph ( preferably higher)

You are not going to be self sufficient with a machine of this size.

I really am not sure where you are aiming with your comments.

Just remember that on the average day you may see 60 to 100W. On many days nothing, other days perhaps 400W and some days too windy to do much good even though the theoretical power level is fantastic. I don't think in general small solar pays for itself with grid tie and small wind may be even less likely.

If you get a moral satisfaction or enjoy the challenge then go for it. If you are out to save money then it's not a clear case and will present many challenges.

Flux

[ChrisOlson]

Well, I would like to know how much power I should be expecting from an 8ft diameter at a wind speed of 5, 10, 15, and 20 mph.

Without looking at my records from the two years I flew my 8 foot turbine, and just roughly off the top of my head from what I remember about it:
At 5 mph, 0 watts
At 10 about 60 watts
At 15 about 160-180 watts
At 20 about 350-400 watts

I do remember the best day I ever had with it was about 3.2 kWh.  The worst day was zero kWh.  I had a lot more worst days than best days.
--
Chris

[Yianie123.]

Thank you for all the help everyone,
John