We were limited to a 20-foot (6 m) tower height by the BLM, because of concerns about aircraft safety and migratory birds. The BLM also required us to add a strobe light to the tower for alerting aircraft of its presence. Unfortunately, I was unaware of this requirement until I arrived in Fairbanks. I felt that it would be a mistake to run another AC line out to the tower, and that it would use up some of the valuable energy we were trying to gain. With this in mind, I decided that an independent system would be the way to go. Since air operations only occur during the summer at this site, PV was the answer.
Two 20-watt, thin-film PV panels supply electricity to two beefy (1,200 CCA) starting batteries. I was replacing the starting batteries on the generators anyway, and given the nature of the application, felt that they would be perfectly adequate for this application. These batteries were only two years old, and showed no deterioration in performance, but in this type of application, we can leave little to chance.
A really efficient and bright 48 LED bulb was selected to minimize the electrical draw. This was enclosed in a weatherproof housing and mounted just below the top guy point on the mast. Buck whipped up an insulated plywood box with the top sloped at 45 degrees for maximizing the summer gain, and it was a done deal.
Experienced RE supplier ABS Alaskan prewired the strobe timer and the charge controller in a weatherproof box, which we mounted to the outside of the battery box. A simple toggle switch for turning the light on and off completed the package. The charging circuit is active all the time, although there will be little or no input for at least four months of the year.
The LED bulb is quite visible even in direct sun, and the whole system seems very efficient. The batteries should have ample capacity to sustain up to a few weeks of operation in overcast weather. It is a clean little system, and I really can’t say enough about the quality of service I received from ABS.
Thin-film PV panels and two batteries (inside box) supply electricity to a safety strobe light mounted on the wind turbine tower.