Three-part image showing Cat energy storage products and Tucson Proving Ground gatehouse
Three-part image showing Cat energy storage products and Tucson Proving Ground gatehouse

Off the grid, On the money: TPG Gatehouse Gets Sustainable Microgrid, Realizes Major Benefits

Overview

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Power Need

The Tucson Proving Ground (TPG) is a 6,500-acre off-grid mining and training site operated by Caterpillar in the Sonoran Desert located 40 miles south of Tucson. For decades, a guarded gatehouse was reliably powered by a diesel generator set, which had logged over 150,000 hours. It was the perfect time for a more sustainable solution.

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Solution

In February 2025, Caterpillar installed a compact hybrid microgrid. Components of the system include 58 solar panels (on a carport-style canopy), a Cat® XES60 battery storage system (24 kW with a built-in microgrid controller), while retaining the diesel generator as a backup power source.

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Results

Prior to installing the XES60 and solar canopy, the TPG Guard Shack consumed ~1800 kWh/month from a diesel generator, requiring over 500 gallons of fuel monthly. Since commissioning, site energy consumption has remained the same, but fuel use has dropped to under 25 gallons/month, with solar now supplying nearly 100% of the site's 24/7 power needs. Weekly diesel refueling has been replaced by simple visual inspections by onsite staff.

Summary

Caterpillar’s Tucson Proving Ground in Arizona upgraded its decades-old, diesel-powered guard gate with a compact hybrid microgrid system in February 2025. The installation – featuring 58 solar panels, a 24 kW Cat XES60 battery storage unit, and a backup diesel generator – now powers the site efficiently and quietly, saving approximately $6,000 per month in fuel costs. This off-grid solution reduces emissions and improves working conditions while serving as a scalable model for remote or noise-sensitive applications.

Overhead view of TPG gatehouse with solar panels
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Key Statistics

20 kW
of solar panels

56.8 kWh
of energy storage

95%
reduction in fuel consumption

97%
runtime reduction

TPG gatehouse showing a guard speaking to a person in a car
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The Impact

  • Lowered overall GHG emissions by replacing continuous generator use with clean solar power.

  • Enhanced energy reliability with battery storage and generator backup.

  • Improved operational insight through real-time data monitoring and solar forecasting.

  • Maximized solar potential with 330 days of sunshine annually in the region.

Quotable

“We’re seeing a lot of interest in hybrid microgrids—on-grid or off-grid. Anywhere customers want to save money on energy, or where power access is limited, this kind of system makes economic and environmental sense.”

Thomas Schwartz
Project Systems Engineer
Caterpillar Electric Power

Closeup of Cactus at Tucson Proving Ground
Closeup of Cactus at Tucson Proving Ground

Featured products

  • Nominal Power
    24 kW (30 kVA)
    24 kW (30 kVA)
    Energy Storage
    56.8 kWh
    56.8 kWh
    Enclosure Rating
    IP55
    IP55

    XES60 (60 Hz)

    Cat® Compact ESS, is a mobile battery energy storage system that supplements traditional mobile power solutions to reduce noise, enable deployment of renewable energy sources, and, under certain conditions, allow customers to operate their generator more efficiently. Designed for rapid plug-and-play installation and integration, the Cat Compact ESS module can be used with any combination of diesel, natural gas or renewable energy sources such as solar or wind.

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  • Battery Energy Storage Systems

    Cat® battery energy storage systems (BESS) use chemical energy to store electricity from renewable and low-cost sources for dispatch as needed. This time shift of energy saves money and supports electric resiliency on-site.

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Overhead shot of a large mine site

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