The tower arrived with nearly all the parts we needed. But one essential project component was missing—the turbine! Unfortunately, it wasn’t scheduled to arrive for two months. The turbine I bought is the Bergey XL.1, a 1 KW rated machine. I chose the machine for several reasons. It is one of very few available wind turbines rated at 1 KW, the right size machine to meet my energy needs. In addition, the manufacturer is headquartered in the United States and has a good reputation for standing behind their product—the XL.1 turbine carries a 5-year warranty.
We located our 120-foot tilt-up tower 149 feet from the house, where it has a clear path for raising and lowering. The most time-intensive part of the project was measuring out the locations for all the anchors, and getting them placed at the correct height relative to one another. I borrowed a laser level from my lab at school to help position and square up the anchors. Each anchor had to be 46 feet from the center anchor, and all had to be equidistant from each other. For the tower to be raised and lowered smoothly, the center and two side anchors had to be exactly the same height (level). This was complicated by the fact that my seemingly flat field actually dropped 15 inches from the front anchor (where the gin pole attaches) to the back anchor. I probably saved a lot of money doing this work myself, but it was challenging and time consuming.
I hired an excavator to dig the holes, and hired him again to fill them after the anchor footings were poured. I didn’t have to make forms for the footings because the experienced backhoe operator left almost perfectly straight sides on the 5-foot-deep holes. The concrete footing that holds each anchor sits beneath about 4 feet of red clay.
I ordered an extra yard of concrete to prevent the embarrassment of running short, since I didn’t “measure” with the kind of scientific rigor I teach to my ecology students at Northland College. I recommend the same to others new to working with concrete. At $90 per cubic yard, it was cheap insurance.
The concrete pour went very smoothly. Joy’s brother Ian saved the day by taking the morning off work to help. “Away from the office doing sustainability project” was the note he left on his office door.
I let the concrete cure for 60 days before diving into the tower assembly. My friend and expert advisor Carl Schwingel helped me install the tower in two days of work. We assembled and lifted the first 80 feet of the tower, got that section straight and plumb, and then lowered it to add 40 feet more. This segmented installation approach is recommended for installing tall, tilt-up towers. When tilt-up towers are first lifted into position, the guy wires have yet to be precisely tensioned. Breaking the installation into two steps eliminates the possibility of the tower sections bending or even buckling under their own weight before the final cable tensioning.