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International Tundra Experiment (ITEX) 

Contact
Tracy Dahl
Polar Field Services
Partner in CH2M Hill Polar Services
+1-303-518-8713

http://www.polar.ch2m.com/
ITEX System 3 at the Barrow Environmental Observatory
ITEX System 3 at the Barrow Environmental Observatory
(Click on images to see a bigger version)
System Solar icon Battery icon Solar photovoltaic to a sealed lead-acid battery bank.
Location Four sites total: Toolik Field Station, Imnavait Creek, Barrow Environmental Observatory, Atqasuk. All sites are on Alaska’s North Slope.
Description Overview:

Four autonomous power and communications systems in support of separate instrument tram system measuring vegetation. This methodology ensures minimal human influence on the study site.

These autonomous power and communications systems were developed by CH2M Hill Polar Services in support of the International Tundra Experiment (ITEX). The experiment runs only during the summer months when vegetation is exposed. However, the systems are deployed the year round and thus must be rugged enough to endure the extremes of winter. Each system has a maximum solar generation capacity of 260 Watts, which in these high latitude locations should result in about 1.5 kWh energy production each day. The two 12 volt, 106 amp hour batteries result in an energy storage capacity of approximately 2.5 kW hours. As such, they should provide more than adequate capacity for this project, even during periods of inclement weather. The systems are easily expandable in terms of both power production and energy storage by 50% should the need arise.

Both AC and DC power are exported from the power system to a distribution box on the end of a 25’ umbilical, providing the project with some flexibility in placement, while ensuring that any wind vortices or additional snow accumulation caused by the solar array is kept out of the study area. Power output to the experiment is limited to 300 Watts continuous on the AC side at 115 volts. The inverter is capable of surging to 600 Watts for limited times (~10 minutes) which is critical for reactive loads such as the tram motor. The sealed inverter provides a very high power quality with a true sine wave output. Power on the DC side is limited to 120 Watts by the 10 amp breaker. This should be far more than what is required by the data logger and other small DC loads.

The power system batteries and electronics are housed in a robust and well-insulated cooler made by IRP Outdoors. This provides a cost effective and highly weather resistant solution. The A-frame is made of 2” X ¼” aluminum angle, providing a relatively lightweight yet strong mounting for the solar panels. The battery/electronics box sits inside the A-frame, ballasting the unit. Steel guy cables can be added for additional security in windy locations.

All of the individual components are light enough to be carried short distances by hand. All but one of these systems were positioned when there was snow cover by snowmobile/sled, and set up after the snow melt. It takes one person about six hours to set up a system.

Specifications:

  • PV array: Two Kyocera KC130, 12 volt, 130 Watt panels in parallel for 260 Watts at 12VDC nominal. Array angle is adjustable for seasonal variation.
  • PV charge control by Morningstar ProStar with integral DC load control 
  • Energy Storage: AGM battery bank consisting of two Concorde PVX 1040T batteries wired in parallel. 
  • Power transmission via #8 MC cable, laid across the tundra.
  • Instrument tower Tyco DC/DC converter from SRI International.
  • Circuit protection provided by Midnight Solar 150VDC rated breakers and Blue Seas fuse block.
  • Power system data acquisition accomplished by discrete sensors and an SRI-developed single board computer (SBC/DAQ).

Operations and Maintenance Manual in PDF  Operations and Maintenance Manual


Data Power system status is transmitted when solar power provides battery recharging. The system also provides Internet connectivity for the researchers when they are present at the sites.
Comms FreeWave FGR2-PE or Moxa AWK-3121-US-T depending on the site.