Polar Power Alaska: Page 5 of 7

approach was that it meant some serious excavation had to be done—by hand. We used the Manta anchors for the lower guy wires, where they will be adequate.

On day five, the weather broke. Nothing is as beautiful as a clear blue sky after days of heavy weather. We took advantage of the break to assemble the tower and wind turbine. Assembling the Proven is not particularly tricky, but a significant amount of time is required. By the end of the day, we were ready to raise the tower.

Raising the Tower

Flights to remote locations in the Alaskan bush are not cheap, so we must always minimize our cargo whenever possible. With this in mind, I decided that rather than bringing in a heavy winch system, I would raise this relatively short tower with a rope and pulley system. Using the base of the tower as my starting point, and the NPS container as the second anchor point, I set up a simple 3-to-1 reduction system.

The first time the tower was raised, I had several Bureau of Land Management (BLM) folks on hand to help out. As it turns out, the rope and pulley system is so effective that two people can handle the operation with relative ease. The fact that we had the tower built with a 20-foot (6 m) gin pole for a 20-foot mast gave us a 1-to-1 lever ratio. The 3-to-1 system on the rope made it fairly easy for two people to pivot the beefy Proven WT600 (155 pounds) into position. In fact, I even did the operation once by myself, just to see if it could be done. It can, but it is definitely a grunt. For safety, we will always make sure that two people are on hand for this operation.

System Description

The primary renewable energy component is the Proven WT600 wind turbine. It is a downwind turbine (blades are downwind of the tower), and really built to hold up to adverse conditions. The permanent magnet alternator puts out 3-phase wild AC, which travels about 100 feet (30 m) total before reaching the Proven controller. The controller box rectifies the 3-phase AC to a regulated 24 VDC nominal to charge the batteries.

The four, 110-watt Evergreen PV modules are wired in series for 48 volts nominal output. The array output is converted to 24 VDC nominal by an OutBack MX60 charge controller. This is an MPPT-type controller, which can significantly increase the real output of the PV array. The controller’s power boost feature works especially well in cold climates, which Ivotuk definitely is. I have seen an output of 510 watts maximum from the 440-watt rated array, so the advantage of MPPT technology is pretty obvious.

Deteriorating Batteries

As stated above, we knew from monitoring the system over the course of the year that we had deteriorating battery performance. However, we didn’t realize how critical the situation was, nor the extent of the damage to the battery bank. Progressive discharge testing performed on site by NPS personnel revealed that one cell was