We built a 1000 watt wind turbine to help charge the battery bank that powers our offgrid home. It's a permanent magnet alternator, generating 3 phase ac, rectified to dc, and fed to a charge controller. The magnets spin with the wind, the coils are fixed, so no brushes or slip rings necessary.

Update: DIY Amp Hour meter for monitoring charge!

All about homebrew wind and offgrid power systems, the complete reference!
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Step 1: Build the magnet disks

We had 12" steel disks hydro cut. We cut a template for mounting the magnets. Then we mounted 12 grade n50 magnets around the outside edge. We then built a form, and poured the resin with hardner.

Step 2: Build the coil disk

We wound the nine individual coils, soldered them in a 3 phase wye configuration, and encased them in resin. We used 35 turns of 2 parallel strands of 14 gauge enameled (magnet) wire for 12 volts. Use 70 turns of single strand for 24 volts. # 3 phase diagram shown here shows 3 stator coils. each of those coils is actually 3 coils in series. coils 1,4, and 7 are series together, 2,5, and 8 are series together, and 3,6, and 9 are series together.

more details, see the following page 15 for the series star, 1-y diagram.


Step 3: Build the bearing assembly

Picture of Build the bearing assembly
Two Harley Davidson wheel bearings are inserted into the pipe, with a smaller pipe locked between them to keep them in place.

Step 4: Construct the blades

The blades are 2" x 6" pine, cut at 10 degrees on a table saw, and sanded into a rough airfoil. Not perfect, but close enough.

More can be found at

Step 5: Further Reading

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This is really amazing. Thanks for sharing this

This looks like a good "blue print"/model for me to use, but do you think using a less restrictive bearing and lighter materials would let the turbine spin more freely and thus produce more energy? For example creating a magnet based bearing to use less resistance and allow the propellors to spin with less resistance. The harley wheel bearings just seem like they would slow it down a lot by creating mechanical resistance. Unless thats what you intended?

Also, silly question, but how long do you have to run the unit to see the 1,000watts? Per hour or per day?

I only ask because I just purchased a house with a 3 phase commercial electrical system for the 10,300sq ft green house, and my thought is to put one of these on either end of the green house to charge a battery bank for heating the raised beds during the winter, and finding a way to hook it up to a converter for our main electrical system to send the overflow energy into the house. It would be cool to have 2-3 of these total because it might cover most of my electrical needs for myself.

Any insights are appreciated. Making my greenhouse off-grid is my goal, and ideally tying it back into my house to offset my daily energy needs.

sspence (author)  crimsonsky8911 days ago
the roller bearings are very low resistance. the 1000 watts is instantaneous, as in right now. You are thinking of watt hours, which is watts * hours. on a good windy day, this machine produced 5 kWh's. mag bearings are very expensive. out of my budget.

Might be helpful counting coils -

sspence (author)  ricardas.novosinskas15 days ago
The magnets don't rotate, and the coils don't need to be counted, there's 9. The rpm of the unit is easily calculated by voltage output.
I mean counting turns when making the coils.
sspence (author)  ricardas.novosinskas15 days ago

That's an interesting thought. I could even automate the coil winder with a stepper motor.

Yap. This is exactly what i did :)

sspence (author)  ricardas.novosinskas14 days ago


a585851 month ago

How big are those magnets each?

sspence (author)  a585851 month ago
1" x 2" x .5"
a58585 sspence1 month ago


rsaxena61 month ago
Spence how do I connect 6 wires of 3 phase coils to 555 wind charger?
Thanks Spence. I would appreciate a circuit diagram if you please.
sspence (author)  rsaxena61 month ago
It's on Step 2
sspence (author)  rsaxena61 month ago
one end of each set of coils connect together, the other three comes down the tower to a 3 phase diode bridge, just like a car alternator. This gives a dc output. You cannot connect this to a typical controller controller, it needs a load connected. Permanent mag alternators typically are not allowed to freewheel (no connection) as they will self destruct. always need a load, either battery, or dump load.
birddseedd12 months ago
Ya know. this kinda stuff sounds great, but, it really isnt all that piratical if you live on grid. average it out i spend 100 bucks or so a month. for me to buy a grid tie inverter or a battery bank/inverter/charge controller is going to cost me 3 grand. thats a 100 dollar a month loan, and i don't even have power yet. Even building my own solar panels will still cost me around 8 grand total. Thats over 150 dollar loan. I would be paying more money.
Wouldn't you basically need the same or simular inverter and/or battery bank for wind or solar? And when talking about expense, if you can go one way or the other or both, then you should.

yes, inverter is needed for any energy source.

as far as wanting to be self sustaining, that is a different subject.

But how long would your loan last? and long will you the power company? No Brainer.... I would rather pay for own for 5 years instead a lifetime for power companies crap

A 25k loan over 5 years is near 500 bucks a month. sure it only lasts for 5 years, but i could invest that 300 dollars a month for 5 years and gain a whole heck of a lot more money than i would ever save in electricity.

But after 5 years ALL of that money could be invested or saved. One never knows what the future may hold, if there even is one. I would rather my money be used for me and my family, now or for down the road freedom. What if the near future brings a collapse of our economic system? That money you would be investing will no longer exist and there will be no more power companies to provide power. We should be moving each dwelling towards self sustainability.

You can get grid tie inverters on ebay for $100-$500. About $250 for a 3k watt which should cover a lot of your power.

Hey mykiscool, can you please show me one. when i looked they were $3500. I need a 10k watt inverter.

sspence (author)  mykiscool6 months ago
They don't work with this wind turbine. Please limit your comments to the topic of the instructable.
mykiscool sspence6 months ago

If grid-tie inverters don't work with this wind turbine, please tell me why. I'm in the process of building this turbine and would like to connect it to my grid-tie inverter. How can I make this turbine compatible.

It does work with grid tie inverters. I don't know why he would think it wouldn't
sspence (author)  birddseedd6 months ago

No, it does not. Why do I think that? Maybe because I'm a wind and solar power designer, installer, and 30+ year electronics veteran. This unit must be used with a battery bank and a diversion load controller.

mykiscool sspence6 months ago

Oh, ok thanks. That clears it up. So it should still work if I connect this to a charge controller and then to batteries and then to an inverter as I'd planned. At first, I thought you meant it won't work at all.

sspence (author)  mykiscool6 months ago

There were a number of posts referring to the inexpensive PV mounted direct to grid inverters. Those will not work. A battery type grid tie inverter (Outback GTFX) will work.

If it works with a load controller, it will work in an inverter. A wind turbine still outputs 12v dc, which can be used by an inverter, or battery charger.

sspence (author)  birddseedd6 months ago

micro grid tie inverters don't typically run on 12vdc. still need a battery to keep wind turbine from self destructing, as micro grid tie inverters turn off when grid goes down, and wind turbine will freewheel without a load.

^^^ what he said

What doesnt work with it?

sspence (author)  birddseedd6 months ago

solar type Grid tie Inverters do not work with this wind turbine. This unit is designed to charge batteries for off grid applications. Some inverters can take battery power and sell back to grid, but not the units that were being discussed which are designed to connect a solar panel directly to line power.

The turbine is just the source, you can do whatever you want with the energy.

sspence (author)  birddseedd6 months ago

You might think that, but this source has particular parameters that need to be met to keep it from self destructing. You might want to take the word from the guy that built it :-)

In michigan i would have to have 10k watt. for a grid tie inverter i cant find one on ebay. if i wanted to go off grid, im still looking at 10 to 15k
sspence (author)  birddseedd12 months ago
So don't live on grid. I spent $20k on my power system (complete), and immediately saved the $30k the power company wanted to extend the lines to my property.
you must live waaaaay out in the boonies, must be nice.
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