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FireFly Hybrid Power System 

Tracy Dahl
Polar Field Services
Partner in CH2M Hill Polar Services

Firefly at Cape Woolley. AK
A FireFly provided all camp power for Cape Wolley, Alaska, the land base for the King Island project. The auxiliary solar array is in the foreground.
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System Solar icon Wind icon Battery icon Generator icon Photovoltaic & wind power system with engine generator and battery back-up.
Location This is a portable system that can meet a variety of applications.
Description The Firefly 120H, built by Energia Total, is a mobile, trailer-mounted, solar and wind power system, with battery energy storage and engine generator back-up. It is intended for use in supplying moderate electrical power requirements, primarily in areas with road access.

Initially equipped with a 400-Watt solar array and a 300-Watt maximum output wind turbine, the unit has been augmented with an auxiliary 320-Watt PV array to boost performance. The specifications below will reflect this addition to the system.

Helicopter pick-up points were welded to the trailer frame to facilitate use in more inaccessible areas.

System Specifications:
  • Primary PV Array (400-Watt): four 100-Watt, PhotoWatt PW1000 modules in series/parallel for 24 VDC nominal system voltage.
  • Primary Array Charge Controller: RV Power Products, Solar Boost 50, MPPT (Maximum Power Point Tracking) type controller.
  • Secondary PV Array (320-Watt): four 80-Watt, PhotoWatt PW750-80 modules mounted on a separate, ground based frame.
  • Secondary Array Charge Controller: ASC 24/16, 24 VDC, 16-A PWM (Pulse Width Modulated) type controller.
  • Inverter: Trace (Xantrex) DR2424, modified square wave inverter, 24VDC, 2.4kW maximum sustained AC output.
  • Battery Bank: Eight Concorde Sun-Xtender, PVX-622U, AGM valve regulated, lead acid. Rated capacity of 220 AH at c/20, 6VDC, 1.3 kWh – per battery. Two strings in separate enclosures at 220AH or 5.2kWh per string. Total battery bank capacity at 24 VDC is 440 AH, or 10.4 kWh.
  • Wind Turbine: Southwest Windpower, Air Industrial, AIR-M13-2.  A 1.14m rotor diameter (swept area), produces 300-Watt output maximum at 12.5 m/s wind speed. 28’ guyed, pole type tower.
  • Engine Generator: Honda EM3500SX, 3.5-kW 120/240 VAC at 3,600RPM. Gasoline fueled, with electric and recoil start options.
  • All appropriate AC and DC disconnects and circuit protection provided. See schematic.

The NSF owns two FirefFy units for use in the Arctic Program. Both have been deployed many times over a six-year period. Each has proven to be a fairly reliable, low emissions, low maintenance power system. These “package solution” power systems make it quite easy to go in and set up a small field camp, with power available right from the start.

The batteries in both units were replaced after five years. This is not quite as long a service life as might be expected, probably due to repeated deep discharge to low-voltage disconnect (operator error). The auxiliary PV arrays were added when the batteries were replaced to help prevent such deep discharging.

One wind turbine failed in year six of seasonal operation. With the auxiliary PV array, the unit was able to support camp loads, while maintaining an adequate charge on the batteries.

The primary maintenance issue has been with the trailer platforms, which have not held up as well as one might hope over the rough Alaskan backroads.

Note: Energia Total is no longer in business. This information is provided as an example of what has been achieved in the past.
FireFly schematic Electrical schematic.
Data Power system supports camp infrastructure only. No system performance or scientific data are logged or communicated on a continuous basis.
Comms System typically powers camp laptops and land mobile and Iridium communications. E-mail and data transfers were accomplished by researchers while on site.