I grew tired of cranking up the old gas generator each time we lost power during winter outages. I said to myself, “I want to do something different—something simple, easy to maintain, something low-cost that I can handle by myself.” And now, five years into retirement, I have this 100-foot-tall monster standing in my backyard.
I started researching building a wind turbine on the Internet, and gathered as much information as I could. Two excellent resource books I recommend are A Wind Turbine Recipe Book by Hugh Piggott and Homebrew Wind Power by Dan Bartmann and Dan Fink.
Constructing the lattice tower was a time-consuming effort. I had to learn to weld and use a cutting torch. The tower is constructed from steel tubing (the top rails of chain-link fence). I located my tower carefully among the large trees in my backyard. I used the oak trees, a 6-ton pulley, and a 5/16-inch steel cable system—raising the tower using a second pulley connected at two different stress points along the tower with a 12-volt, 12,000-pound winch. An oak tree acts as a “gin pole” to raise the turbine; other trees help support the main tree (you can pull one over, trust me). I can push a button to raise and lower this homemade renewable energy system.
Anyone handy with tools and who has patience to learn can create a similar device, even if at a lesser height or capacity than this project. The turbine is just a simple homemade alternator, using a six-stud trailer-wheel hub with two bearings. With 32 rotating rare-earth magnets next to a three-phase fixed stator wound by hand with #10 copper coils, there’s really not that much to it. I like to keep things simple—I went with this design because it’s simple and it works. I’m always working on it, enhancing it, and making it better. I’ve seen it generate more than 3 kW at times. With a 1 kW solar-electric array, I’ve been pleased with the results—cutting about 30% off the old electric bill.
This is a 48-volt hybrid (wind/solar) off-grid system with three parallel Magnum Energy inverters that feed a separate 150 A breaker panel in our home to provide standard 120/240 VAC electricity. The hybrid system charges 16 deep-cycle golf-cart batteries, which gives us at least 24 hours of backup with no wind or sun energy input.
The solar-electric array is eight 12 V, 130 W modules, with two groups of four in series to provide a 48 V output. The other four modules are configured in the same way. Both 48 V series strings are then connected in parallel to a 60 A Morningstar controller. The array is mounted on a large frame with 12-inch casters and tie-downs, so I can easily rotate it on the deck to maintain a higher level of performance, morning to sunset.
The turbine and solar-electric modules maintain a good charge on the batteries. I use a Morningstar relay driver to monitor battery voltage and amperage, and it automatically switches if there’s wind or solar energy to be had. I also have the relay driver programmed to apply a dynamic braking relay (shorting out the three-phase alternator) if turbine blade overspeeding occurs (the battery voltage suddenly rises) or if the Morningstar diversion controller or load resistor fails.
I would have paid more than $25,000 to purchase such a system commercially. My project cost was between $5,000 and $7,000, including the batteries.
Roger Beale • Evington, Virginia