Intro: DIY 400 Watt Wind Turbine
These plans detail how I built a wind turbine in my garage without any special tools for just over $200. Many of the do-it-yourself designs are either toy projects or unlikely to hold up in strong winds. This wind turbine will withstand 40+ mile per hour winds and produce electricity with as little as 15 mile per hour winds.
I started out with one of those aforementioned toy projects, but soon realized that this design would not stand up to the high winds in central Iowa. After months of trial and error I finally have a design that is strong and effectively produces usable electricity.
I would just like to note that I am a high school senior with no prior experience with electrical systems; so before you tell yourself that building a wind turbine is out of your realm, trust me, it isn't as hard as it sounds and anyone who puts their mind to it can do it.
Step 1: Materials
Note: I would recommend getting galvanized steel for all parts that will be above ground. Regular black steel will rust within a couple of months unless you paint it often.
The above picture is a spreadsheet of all the parts I used while building the wind turbine itself.
Step 2: The Generator
The generator is the heart of your wind turbine project and it is important to get a good one. What you want to look for is an industrial DC permanent magnet motor. I got mine on eBay for around $65, and it came with a drilled hub meant for attaching wind turbine blades which saved me a bunch of time trying to make one myself.
My motor is rated for 90v DC at 1750 RPM. Using it as a generator, it will do just the opposite, with 80% efficiency. So if I were to spin this motor at 1750 RPM it would produce 72 volts of electricity. Now, I obviously will not be spinning this motor at 1750 RPM, but you get the concept. In order to charge my batteries which are 12 volt deep cycle marine batteries, the generator needs to be producing at least 12 volts. If you do the math, then I would need to spin the motor at a minimum of 233 RPM to charge my batteries.
With my PVC blades, a steady 15 MPH wind will easily spin this turbine at 233+ RPM, allowing my batteries to be charged.
Step 3: The Blades
Rather than spending hundreds of dollars on blades for my wind turbine, I made my own blades out of scrap PVC I had lying around. Everyone out there tells you to use 8" PVC for wind turbine blades, and let me tell you, it works far better than the 6" I was able to get. I had to get creative to make the 6" PVC work (less curvature than 8").
I started by cutting down my PVC pipe. The rectangles I made are 5.5" by 24". I then cut these down to triangles where the short end is 1.25" wide. After that, I cut out a triangle on the end where it will attach to the generator hub. I clamped the blades in a vice when I cut this and drilled the holes so they would all be about the same.
Use scrap 90 degree angle iron when marking to cut; you will get a straight line that way.
You can use a hacksaw, but I would recommend a reciprocating saw.
Use saw blades meant for steel (fine tooth).
Step 4: Blades, Continued
In order to make the 6" PVC work, I added to the design. As illustrated in the pictures, I used steel garden edging stakes with holes drilled in them to add to the length of my blades. The most important part of this though, is the fact that I bent the stakes so the blades are sitting at about a 30-45 degree angle to the hub, allowing the wind to push them sideways and around rather than back, putting less strain on the guy wires and foundation, and producing more electricity.
Step 5: Adding the Wind Vane
Before you get started with this step, I would recommend painting the 48" square tube; mine was not galvanized and it rusted within a few months, so I had to take it all apart again to sand and paint it.
Mark a line down the center of the 1" square tube and cut a slit from one end of the tube a foot long.
The piece of sheet steel will slide into this slit. Drill two holes through the tube and sheet steel, and bolt it all together.
Step 6: Attaching the Generator
First you want to drill the hole for your power cord. Set your motor on top of the square tube (the motor should be flush with the end of the pipe). Drill a hole where the power cord lines up; I would recommend an oversized hole to make sure the metal does not slice into the cord.
You will next attach the 1.25" floor flange to the square tube. The flange should be just behind where the motor sits (it should be pretty close to being the balance point of the tube). Drill two holes and bolt it on.
Drill a third hole in the center of the flange for the cord to go down the pole. Thread the cord coming off of the motor through both of the holes you drilled and attach the motor to the pipe using large hose clamps (make sure they are very tight).
Note: my motor had a plug on the end of the cord when I first got it, but I removed this in order to thread it through the pipe.
Once all this is done, you will thread a 1.25" diameter pipe nipple onto the flange. I used one that is 24" long, but you would be fine with 18" or maybe even 12". This will slide down over your main pole which is 1" diameter.
Step 7: Foundation
In my experience, a frame staked down resting flat against the ground is not sufficient in high winds, and will allow the wind turbine to tip over, damaging it and snapping the blades. In order to withstand high winds without problem, I dug a foundation and filled it with dirt and concrete in some key places.
I basically threaded together steel pipe, and dug a hole for it to fit down in.
I poured cement around all five of the vertical pipes, and put dirt over and around the rest. There may be more efficient ways of doing a foundation for this, but I just didn't want to take any more chances.
Once it is all in the ground, there will be a male fitting sticking not very far out of the ground. The main pole of the turbine also has a male fitting, so I put a 1" female tee in between the two. This serves a dual purpose as it also is where the cord that runs from the generator down the pole comes out.
Note: The cord that I strung up the pole is just an old extension cord with the male end cut off.
Step 8: Guy Wires
For guy wires, I initially used high strength paracord, but they snapped in high winds, so I transitioned to using heavy duty dog leashes made from braided steel cable that came with very sturdy screw-in stakes. I attached them to the main pole using two grounding clamps. The clamps came with bolts and I replaced these bolts with I-screws that the guy wires could easily clip on to.
Step 9: Charging Batteries
I have two deep cycle marine batteries wired in parallel which I charge using my wind turbine. You could easily just hook the batteries up to the positive and negative of the generator with a diode to make sure the electricity does not flow from the batteries to the generator, spinning it like a fan, but I have opted for a charge controller. I got mine from Missouri Wind and Solar (www.mwands.com), and it was made right here in the USA. This has been a very trouble free solution for my application (I don't have to check it often since it regulates charging automatically).
When you purchase a charge controller from Missouri Wind, they recommend you purchase a dump load resistor with it. The charge controller will divert the electricity from the generator to the resistor when the batteries are full, making sure the wind turbine is always under load, preventing it from spinning out of control. I have never found the dump load resistor to be necessary, seeing as I have never completely filled my batteries (they are almost always under load).
If my electrical box looks like a mess of wires to you, don't worry, because if you plan on doing the same sort of setup that I have done, Missouri Wind sends wiring diagrams when you purchase a charge controller from them.