Arizona G&T Cooperatives What We Do Renewables

Renewables

Apache Solar

From left, AzGT’s Barry Brown and Mike Nelson tour Apache Solar with Chet and Jessica Wold, who like the fact that they’re getting renewable solar power from the project. The Wolds are members of Sulphur Springs Valley Electric Cooperative.

Apache Solar Project, located adjacent to Apache Generating Station, provides 20 megawatts of renewable power to our six Member cooperatives and to Electrical District No. 2,  a public power operation in Casa Grande, Arizona, and an AzGT customer.

Apache Solar Fast Facts:

  • 20 MW AC power generated
  • 77,053 panels
  • 320 watts produced by each panel
  • 134 acres of AEPCO property house the solar array
  • 9 2.5-MW inverters convert the DC power to AC
Apache Solar
In addition to the Apache Solar Project, we’re exploring transmitting wind energy from eastern New Mexico to Apache Station, and we’re analyzing battery technology to make solar and wind generation more cost-effective and reliable.

Shining a Light on the SunAnza Project

We worked with our Member in Anza, California, Anza Electric Cooperative, to complete SunAnza, a new 3.4-MW solar and battery energy storage project that helps Anza EC meet California’s renewable energy standards.

Barry Brown
Barry Brown, AzGT executive director of engineering and transmission, discusses storage capabilities of the Anza EC battery storage project, built with AzGT engineering and design support in conjunction with Anza’s second phase solar array, SunAnza Phase II.

Anza, California, is a small, remote community in the mountains above Palm Springs. Its growth is limited by the capacity of a single Southern California Edison transmission line that delivers power. The line has inadequate capacity to provide for load growth in the area and, unfortunately, is among the least reliable in California.

In 2017, Sierra Southwest Cooperative Services (Sierra), AEPCO’s sister renewable G&T cooperative, completed and placed in service the 2-MW SunAnza project on behalf of Anza Electric Cooperative. AEPCO worked with Anza EC, the National Rural Electric Cooperative Association and the U.S. Department of Energy to study the benefits and costs of various designs. In late 2019 the team settled on a design to add 1.35 MW to the SunAnza facility, along with 4 MWh of Tier 1 battery storage and microgrid control technology. Construction was completed in December 2020.

An additional 5.2 MWh of battery storage expansion is underway. When complete, Anza EC will be better positioned to respond to power or transmission outages.

When reliability is not a primary concern, the new battery storage system will allow energy generated during solar hours to be shifted to late afternoon or night—when electric loads typically peak—to reduce more costly power supply costs during these hours.

Sierra Southwest Cooperative Services, Inc., a part of AzGT, serves the renewable-energy needs of AzGT Members and customers by providing a mechanism for maximizing solar and other renewable tax credits through cooperative lenders.

AEPCO’s financial team worked with cooperative lender CoBank to finance this project through a lease-back arrangement between Sierra and CoBank’s Farm Credit Leasing subsidiary. This lease structure provides a repeatable formula that allows our cooperatives to monetize federal solar and storage tax credits and provide the lowest cost resource to AEPCO’s Members.

Optimizing Hydropower Allocations

AzGT optimizes our Members’ hydropower allocations from the Hoover Dam. We bring in this low-cost power from the federal Western Area Power Administration on an aggregate basis, dispatching it to Members on an on-demand basis, and billing them according to use. We work with our scheduling and trading partner, ACES, to dispatch Hoover power hourly.

We also coordinate Hoover power with power from our Apache Solar Project. We have the flexibility to quickly cover loads when solar unit output changes rapidly due to cloud cover or other conditions.

Balancing Renewable Sources Leads to Efficiencies

  • 00:00 (Midnight): Natural gas and coal generation at Apache Station are dispatched around the clock.
  • 06:00 (6AM): The Apache Solar Project at Apache Station can generate up to 20 megawatts of energy, but only when the sun shines. Arizona is rated as the number two state for the amount of sunshine available— second only to Nevada—but solar generation is unpredictable.
  • 18:00 (6PM): Low-cost hydropower from Hoover Dam is generally available 24/7, but the allocation is limited. We work with ACES to use the resource when it has the most value—often when it complements solar generation or as a peaking resource to reduce costly power purchases.