My Experience with Wind Turbines

[SparWeb]

Hi,
I've joined this forum recently, but I'm not new to Renewable Energy projects. I've been building wind turbines for myself for 20 years and it's been a very satisfying project all this time. I'd like to tell my story - I hope you folks will enjoy it.

I'm entirely aware of failed WT products that don't deliver what they promise, and expensive WT project boondoggles in the news. Obviously, when more is promised than can be delivered, disappointment ALWAYS results. I don't want to talk about that stuff. I'm here to claim that I figured out how to build WTs that deliver what's expected.

I had a lot of help along the way. Hugh Piggott's plans were essential to getting me started on the right foot when I built my first WT's. The HAWT designs that he provided in workshop plans and United Nations sponsored development projects are extremely valuable. Any WT that promises more than what a Hugh Piggott WT can deliver is simply false. I also came across the old Fieldlines forum, which, back in the early 2000's, had members like Zubbly, Ghurd, Ed, and Jerry, who were ingenious tinkerers who could make a generator out of anything. With Hugh Piggott blades and Zubbly generators, I had the ingredients for successful wind turbines.

Here's my first HAWT wind turbine, first raised July 7, 2007.
Note that it had 4 blades but I soon changed it to 3. Its tail was too small, eventually being replaced by a tail vane 3x bigger.
You can barely see the generator - that's because it's too small, too. It burned out in less than a month. Examining it, I realized what I'd done wrong, lesson learned. In the meantime, I had been given an old industrial 3-phase motor by a friend. Since I had already started planning to convert it into a generator with Neo magnets, my WT was back up and running only a couple of months later.


You can see details of the motor after being converted, but you have to see inside to understand what I really did to make it into a generator. Note the extra long shaft coming out of the motor - I turned a whole new rotor and shaft using the lathe and milling machines at work. And I made a new hub, too, fitted with just 3 blades. The tail was also improved. At the time, my welding skill was still pretty brutal! I think I did that one all with my acetylene torch.



This WT ran for a year and a half, until an accident handling the tower caused it to fall and be smashed!



Not daunted by this! I had measured performance of this generator and realized that there were still improvements to be made on what I had previously done. The tower was completely recoverable, and so was one of the blades. Given that I had removed the 4th blade before, I only had to make 1 blade and a new generator.

I'll hit the Post button now, and continue on in a subsequent post. Not sure how many pictures can go into one post at a time.

 

[Jacob89]

Definitely interested in seeing more of how you converted the three phase motor.

 

[SparWeb]

After the accident, I set to work converting another motor, one much better for the task of generator. In the meantime I made a quick-and dirty motor conversion and some replacement blades. That tided me over with a workable wind turbine for a year and a half. In that time I learned a lot more about the generators, the physics involved in a generator's performance, and how to match any generator to the performance of the rotor blades. I was given another motor - a very good, if old, one, very suitable to be converted. It was worth doing it right.


The picture below is a pretty good illustration of what I did to convert the motor. The basic wiring of the motor is unchanged. This 3-phase induction motor has had the entire "squirrel cage" rotor removed from its central shaft. I made a new rotor and machined flat surfaces on its faces. In the middle of every machined face is a tapped hole. I placed neodymium magnets on, which held firmly to the iron rotor, but I screwed them down anyway. Actually I also bonded them with an aerospace adhesive, just to be absolutely sure. The magnets alternate between squares and rectangular shapes, which cuts down on the "cogging" or torque ripple. I kept all the remaining parts of the motor virtually as-is. I wasn't that aggressive at removing rust although some was definitely removed - it was a very old motor when it was given to me. Oh, obviously it needed new bearings.




I recall using this generator for some electricity demonstrations for my son's grade-6 class before finally mounting this on the tower and blades.
Making new blades took a bit of time - I resolved to make 2 new ones, not just one, and pick the best to match and balance with the two old ones.
Eventually everything was ready to go back together.



You can still see I was making parts out of "other things" such as the hub made out of a chain sprocket. It was convenient because these sprockets (from Princess Auto!) are readily fitted to hubs that exactly match common motor shaft sizes. Easy to weld up a hub.

By September 2010 it was back in operation. I wasn't happy with the tail furling, though. In the photo below you can see my technical "shrug" in the form of a cable to limit that tail swing travel. A few months later I had welded up a new mount for the entire generator and a new tail. By then I had a nice Miller MIG unit and it is a joy to use that welder.

 

[SparWeb]

So far I hope you can tell this was always a learning process. I made mistakes and I kept going. Every successive machine was better than the last one.

I didn't mention it before, but that accident dropping the tower was a huge lesson to me. I thought I had been working safely but the reality was that I didn't know what I didn't know. After that accident I re-did the structural analysis of the tower, and incorporated a winch and pulley system to raise and lower it. Previously I had just been attaching a long cable to my truck or tractor and using that to lower it down. Well, at some point I became cavalier about that, and the result was watching the tow cable fly free of the truck and the tower drop like a felled tree. Timber.

Nothing more than my pride was hurt. It motivated me to improve, though. I had not more tower accidents, nor really any "close calls". I have checklists and procedures to follow when lowering/raising the tower, and limits on when I can and can't do it.

Here's the tower I use now. I built that in 2021, so before I get into that development, I'll go back to chronological order after the 2010 WT replacement.

 

[Jacob89]

Can you say more about the motors you've used? HP rating, number of poles etc?

 

[Hogheavenfarm]

Very nice write up, I built mine with frequent reference to Hughs pages and Fieldlines as well. Mine is an old F&P conversion, and while it is up and running I need a much taller mast to position it on.

 

[SparWeb]

Hi folks,
Let me continue my story. Gather 'round...

(I think I'm going to stick to the overall story, first. Several of you have asked about details, which I'd love to share. I think I will set up the context, first, and as the details come out, they'll fit in the bigger picture better.

Yesterday I got to 2010 where I replaced a smashed turbine with a much better performing one. In fact I was really pleased with how well it worked and was reluctant to change it for many years. I just lowered it every once in a while to replace bearings. It ran and ran without complaint (except squealy bearings that one time).

Several things had gone right for my 2010 wind turbine to be a success.
1) Carved wood blades that proved to be very robust in my weather. I live near Calgary Alberta. 5 months of winter, frequent storms in the summer, but not much rain, in total. Cedar is my wood of choice. I had worked with it before on other projects before this wind turbine.

2) Motor conversion which also proved to be rock-solid. If any of you have heard of an "axial-flux" alternator, or done some of the Hugh-Piggott DIY turbine projects, you'll be familiar with the kind of alternator that's got coils potted into a disk of epoxy. I built one of those myself a long time ago, but it burned up because epoxy can't dissipate heat very well. The temperature limit is very low on those generators. Converting industrial motors I benefit from all the wiring completed, plus insulated to very high temperatures, not to mention precision machined parts ready to turn at 3600 RPM which makes them overdesigned for my speeds below 600 RPM at most.

3) Matching between blades and generator based on my self-taught lessons in wind turbine fluid dynamics and performance modeling. I put some tools to use that I learned to use at work (engineering) that gave me an advantage. The matching process gave me some control over the relative sizing of the generator and the blades. It answered questions like "is 8-feet diameter enough?" and "should I put 1/2" thick magnets on the rotor, or do I need 3/4" thick?" It kept the costs under control, too.

4) Setting the tail to furl (fold up) at a very low wind speed. To many people this sounds counterintuitive. "Faster = more power!" Well I'm not looking for more power, I want more energy, and I don't need the things to wear out by whipping around so much in a storm.

There were several reasons I got it close to right on my 3rd try. I benefited from smart people on internet DIY forums (like Fieldlines, if you've ever heard of them), I had friends who gave me parts and access to tools to fabricate the parts well, and I studied what wasn't working on my previous tries, so that I could do better. I built data-loggers to help me measure what was going on, which provided a lot of insight.

Here's a shot of it from 2011, with a cake of leading-edge ice on one of the blades. I shut it down because the mass imbalance was shaking everything! Note that I still hadn't fixed the tail at that point (still trying my luck, it seems).




Here's a picture inside my battery shed at that time. Below is a TRACE SW 4024 inverter. No, it did not say "Xantrex" on it. I'd also rigged up other gadgets. The one in the middle was an Auxiliary diversion load timer, which switched on an AC diversion load powered by the inverter, rather than the DC diversion load. By discretion I mean that if the discretionary load was unplugged, not working, or switched off, then the DC diversion load was just go ahead and do its thing. But if the conditions were met, the discretionary load would run water heaters where our horses drink at troughs, to keep the water from freezing. It was a great use of RE and that little gadget paid for itself in energy savings in only one winter of use.

 

[SparWeb]

In 2012 I built a new chassis to mount the generator at the tower-top, allowing it to yaw with less risk of binding the cables hanging down. Another major improvement was a much more solid tail. The tail of the wind turbine is hinged so that it can fold in strong winds. In light winds, simple gravity keeps the tail down because the hinge is slanted 20 degrees. When folded up it contacted a rubber bumper before it hit anything on the generator. On the left you see a small motor that I used for sizing it up, but not the generator itself.

Actually I did do a conversion on that motor, too, but it was the little one to "tide me over" in 2009 and I haven't used it since. It was terrible.




Edit:
Here is a close-up of how the vibration isolation works. The base of the motor is bolted through a set of rubber pads, both between the motor's foot and the frame, and also a tube of rubber is wrapped around the bolt. This is really good at isolating the "hum" of the generator so that you can't hear it from the ground.




In 2013 the project was to relocate the batteries to a new shed that would give me room to work on "the balance of the system". From left to right you see the Trace SW4024, the stack of Absolyte AGM batteries, the Tri-star controller for diversion load control, and the Xantrex C40 controller for the set of solar panels that I had on top of the shed at that time.

 

[SparWeb]

OK so I didn't do much with the wind turbine between 2013 and 2019. Just let it run and do its thing.

I did develop an Arduino-based data logger that I am still really happy with. It tracks RPM, voltage, current, temperature, and total energy.
Got a little fancy with the illuminated color LCD. I set up the colors to mean "blue = off" "Green = slow" "Yellow = fast" and "Red = problem!".
Later I got fancy, and tried to add a WiFi transmitter into it, which worked for a couple of months but died when it got cold.

 

[SparWeb]

Here's what those cedar blades that I carved in 2009 looked like, when I finally took them off in 2019. 10 years had scoured all of the varnish off, and there were even dents from hail, splits and cracks, too. Despite that, the WT was running well. By the data logger, the performance was not significantly degraded.
Obviously it was just a matter of time before something would fail, so these blades were retired with honor. The generator was still running well (replaced the bearings again!) and I didn't need to update the tail, either. Just grease it a little.



That summer I had been carving a new set. The data logger had not only helped me measure performance, but also determine that I could put even bigger blades on the generator. The caveat was that I had to curve the blades substantially to ensure they were optimized for slow speed.

 

[SparWeb]

Here it is in 2019 with the new 10-foot diameter blades. Laminated cedar, varnished with Varsol Diamond. The leading edges have erosion-resistant tape on them like the kind used on airplane propellers. I had the hub made by a machine shop and the plates to join the 3 blades was laser cut and powder-coated. The same generator that had been running since 2009 is still there. The cable is still suspended at the top and dangles down the center of the pipe tower.






I didn't mention it before but I also raised this tower from 40' tall to 50' tall. That was really the limit though, and I abandoned that location and the "pipe" tower structure after that. Too wiggly jiggly like spaghetti.

Also working against the tower at that time was a row of trees that had grown from 20 feet tall when I started, to 60 feet tall, just to the west of the tower. The photo above is looking north, and those spruce trees are relatively small and not a wind problem. However, lowering the tower around them proved to be complicated and invited guy-wires to get snagged. These trees are a necessary wind break around the horse paddocks.

The last straw for that tower was that my data logger showed me poor performance in west wind, because of the trees blocking it. For equal wind in other directions, the performance of the WT was better, making it clear that the trees were having an effect. Most of the wind we get here, in the winter and spring, is from the north and west, therefore obstructions from the west are costly.

 

[Crowz]

Those blades are a work of art !

 

[SparWeb]

Yeah guys, you're going to look at a thing like this for 10 years of your life, and so will your neighbors.
It really should look a lot nicer than white fiberglass. It's not a bathtub.

The chinese wind turbines that people buy for less than 1000 bucks are really chasing the race to the bottom. Nothing I make is going to look like that.

 

[SparWeb]

Definitely interested in seeing more of how you converted the three phase motor.

Started a fresh thread on that topic:

Thread 'Converting Industrial 3-phase Motors into WT Generators'

Jan 6, 2025

Some of you have said you're interested in the process of converting an industrial induction motor into a generator.
https://diysolarforum.com/threads/my-experience-with-wind-turbines.97428/#post-1313614
I mentioned doing this several times in my other thread about building my own WT's.

I've done this several times, with success. It's fairly easy, but you really need to have manufacturing tools available to do it right. If you don't have a lathe or a milling machine, or don't know someone who does, do not worry, we can talk about ways to access these tools, later.

Here are...

• SparWeb
• Replies: 20
• Forum: DIY Wind Turbines and Hydroelectric

• 

 

[doing it different]

All very cool. Do you have screw anchors holding that tower? How high is it in this picture?
Any pictures of how you are tilting it.

What are the output numbers you are getting...

 

[SparWeb]

Yes, I use 5' long screw anchors with 6" plates at the base. There is one anchor at each of the guy wires, and one more by the winch to hold a pulley. The tower is exactly 70 feet (21m) tall.
The tower is a common DMX-68 truss-tower. Usually used for radio, I have reinforced this one to make it accept a wind turbine.



Here are some pictures of the tower building process.
There are 3 screw-piles in the ground. They were installed with a bobcat and a special hydraulic drive attachment. My soil is mostly fine-grained clay, making it rather easy to install these. The screw piles are 15 feet long, 4" diameter, and rated for about 10,000 pounds each. Way over-kill for this tower but this is cheaper than a gigantic block of concrete, and a lot less back-breaking work. They are also removable, so if I have to relocate the tower for some reason, it's possible.



On top of the three anchors is a structural frame that serves as the interface to the legs of the truss-tower. The leg on the left is extra long and double-strong because it's also the hinge-point for the gin pole. The gin pole is a 3.5" pipe, which hinges around a 1" diameter pin passing through the extensions.



It tilts down because it's hinged at the axle. Once it's vertical the 3rd leg lines up with the stub. Push the bolts through and tighten, that's it.
The complicated part of raising and lowering is managing the guy wire cables and the winch cable. That requires some discipline and attention to detail. Thankfully it is a lot less dicey that it was on my previous tower, and I'm very glad I did this. It did cost a fair bit of money, even using a used tower and building most of it myself.)

 

[SparWeb]

What are the output numbers you are getting...

Good question. Here are the performance charts I developed in 2020.

I built a datalogger to collect my own data. I bench-tested the generator before installing it in the wind turbine, and one of the checks on the datalog that I did before accepting its data was to verify that it was recording values consistent with the original bench test. You can see the data below collected from 3 separate logging runs in 2019. The reason they are different is because the battery voltage was substantially lower on the 20th (green dots). I measured this during my bench tests so I confirmed this, too.



In the next graph below, the wind power values (red line) are basic calculations based on the wind power law. For the datalogs used for my performance evaluation, I included data from my weather station for wind speeds and barometric pressure (and air density). The output power relative to wind speed is found by just crossing the measured power with the speed at that moment. But that hides the complexity of the calculation because using the raw data to do that would lead to a ridiculous and useless hash of dots. To get reasonable averages, I needed hours of data to be collected, even though the data was sampled and recorded by the datalogger every 10 seconds or so.

To manage all of this data, I binned the data in 1-minute chunks, and tried to use statistical methods consistent among the data reduction that the weather station uses (automatically, which I can't control or change) and the data from my datalogger.

Note that the "input power" curve is created by cross-referencing the bench test data, where I collected the generator's input and output power measurements. All of the in-situ values of wind turbine output power were correlated to the bench-tested input power values.



The wind speed and associated turbine rotor speed data allow for a fairly direct calculation of Tip Speed Ratio (TSR). When I started collecting datalogs of my wind turbine over a decade ago, I began to learn that the things people like to say about TSR is often inaccurate, sometimes misleading. I went back to basics with some fluid dynamics textbooks and confirmed that TSR should do this with increasing wind speed. I had designed my wooden blades for TSR=5, so I guess I hit it right on.



Finally here is the number we're all happy to see, the Coefficient of Performance of the wind turbine (Cp). Really happy with the results when I was able to demonstrate this. Note also that the peak CP coincides with the actual measured TSR matching the as-designed TSR of the wooden blades. After many tries, I seem to have gotten it right. It was a satisfying pay-off for 15 years of learning and experimenting.

 

[Cris2112]

Thanks for sharing all of this information and it's nice to see someone with a passion to make wind turbines work. I am interested in suplimenting my solar with a small turbine. I'm looking at a unit that will produce 400 to 600 watts steady. That's my idle power use at night. It would help me in the winter for sure.

 

[SparWeb]

Hi @Cris2112,
Do you already have a battery bank in your system. Are you grid-tied or off-grid?

 

[sunshine_eggo]

Thanks for sharing all of this information and it's nice to see someone with a passion to make wind turbines work. I am interested in suplimenting my solar with a small turbine. I'm looking at a unit that will produce 400 to 600 watts steady. That's my idle power use at night. It would help me in the winter for sure.

"small turbine" = shit power production in 99.9% of cases.

400-600W steady would be a 4 meter diameter (13' diameter) wind turbine in constant 15mph wind.

OR 2 meter diameter (6.5' diameter) wind turbine in constant 23mph wind.

Just because a wind turbine says "1000W" it doesn't mean you'll get 1000W. The vast majority of the time, for most people in most locations, wind is not even remotely worth the squeeze. Look at our friend (@SparWeb) here... He's dedicated YEARS to it. That luscious 10' dia beauty would need at least 16mph steady at all times to generate 400W.

Please read the following:

Resource icon

Wind Resources

Feb 9, 2021

Various resources for evaluating if Wind is right for you

• snoobler
• Planning and Sizing Tools

 

[OzSolar]

That luscious 10' dia beauty would need at least 16mph steady at all times to generate 400W.

It really is a beauty! Not going to lie, I'm a bit jealous of @SparWeb 's skill set. Someday I'm going to build a WT using Hugh Piggott's design.

You've reminded that I've been meaning to ask @SparWeb about his graph that clearly took many years of hard work to derive.

I assume red line is the "theoretical power" for a 100% efficient wind turbine. It lines up with the cubic wind power formula, 2X's the wind speed 8X's the power. EG: 100 watts at 10 kph and 800 watts at 20 kph.

Continuing with my assumptions, the bottom line (highlighted below) is the useable power actually collected by the turbine. If I've got it right that turbine never puts out more than ~280 usable watts.

Did I get that right?

Edit to try to add some clarity.

 

[Cris2112]

Hi @Cris2112,
Do you already have a battery bank in your system. Are you grid-tied or off-grid?

I have an 800ah Lifepo4 bank. All off grid. We have a grid tie service but I built the system to be off grid.

 

[Cris2112]

Hi @Cris2112,
Do you already have a battery bank in your system. Are you grid-tied or off-grid?

Sorry for the delay. I'm just now learning the ins and outs of this forum.

 

[SparWeb]

It really is a beauty! Not going to lie, I'm a bit jealous of @SparWeb 's skill set. Someday I'm going to build a WT using Hugh Piggott's design.

You've reminded that I've been meaning to ask @SparWeb about his graph that clearly took many years of hard work to derive.

I assume red line is the "theoretical power" for a 100% efficient wind turbine. It lines up with the cubic wind power formula, 2X's the wind speed 8X's the power. EG: 100 watts at 10 kph and 800 watts at 20 kph.

Continuing with my assumptions, the bottom line (highlighted below) is the useable power actually collected by the turbine. If I've got it right that turbine never puts out more than ~280 usable watts.

Did I get that right?

Hi Oz,
Good questions.
You're right about a lot of things. I could have explained better. The red line is the theoretical limit, as you put it. The black line is mechanical power at the rotor shaft, and the brown line is the electrical power once mechanical power is converted to electricity, flows through 200 feet of buried cable, and drops to DC in the bridge rectifier. The losses aren't large in the system, but they aren't negligible, either. My conversion with permanent magnets also imposes low efficiency on the generator, because it's no longer operating at its design speed (which was 1800 RPM when it was a motor).

That said, note the wind speed scale only goes up to 30 kph on that chart. That's just the limit of the reliable data I collected. I get stronger winds in storms. The power curve keeps going up and up, and I certainly have seen >1 KW, many times, but it's brief. The furling tail is set to keep things down below 500 Watts by preventing it from turning faster than 400 RPM. This makes the machine much more durable.

Here is an example of 17.3A * 58.89 V = 1019 W
I was calibrating a new datalogger that day (April last year). The wind was gusting to 50 kph (30 mph) at the time.

 

[SparWeb]

I have an 800ah Lifepo4 bank. All off grid. We have a grid tie service but I built the system to be off grid.

Hi
So just putting together the 2 posts you made, you want a RE source like wind that can sustain your battery bank overnight, and I suppose you have solar for daytime generation. You mentioned that your consumption is about 500W overnight. That seems a bit high. Could be a lot of things, like electric heat or a central furnace fan, but instead of guessing, what can you say is the cause of this consumption?

In the winter, the overnight period is literally 14 hours of the day (for someone in Illinois) meaning your overnight usage is about 8 kWh. From an 800 AH battery bank (assuming it's wired at 48V) then you can store about 38 kWh. More like 30 kWh to be realistic. So it seems like you have lots of capacity. Have I calculated wrong?