Alcatraz Powered by Microgrid

July 22, 2014 By Linda Hardesty

Alcatraz energy manageAlcatraz Island off San Francisco is being powered by a commercial scale microgrid system, reducing much of the diesel fuel costs required to power systems on the National Park Service property.

The microgrid system is comprised of a 350 kW PV array, Princeton Power Systems inverters, a Princeton Power Systems site controller, two diesel generators, and a lead-acid battery rack.

The total island load varies typically between 50 and 80 kW. The PV array produces a peak power each day of roughly 175 kW. The batteries absorb all of the excess PV when PV exceeds the load requirement, and they deliver whatever load the PV does not cover at all other times.

While the majority of the island’s power is produced by solar, batteries provide help when the sun is not present, as does the generator when both solar and battery storage are not available. The generator is automatically turned on and run at maximum efficiency to recharge the battery bank, then turns off for 3-4 days at a time.

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