Client Blattner Energy, M.A. Mortenson
Location San Antonio, Texas
Scope 150 MW, Phases 2-5 of 450 MW solar project

Alamo Solar Projects 2-5

Project Details

Westwood’s Role

  • Electrical Engineering
  • Civil Engineering
  • Surveying
  • Aerial Photography
  • Environmental

Overview

Alamo Solar is a portfolio of solar PV projects that, when complete, will provide 400 MW of power to CPS Energy the municipal utility of San Antonio, Texas. Westwood has provided services on phases 2 through 5, to date.

  • Phase 2:  30 acres 4.4 megawatts
  • Phase 3: 30 acres, 5.5 megawatts
  • Phase 4: 500 acres 40 megawatts
  • Phase 5: 800 acres 100 megawatts

Westwood was initially hired by construction contractor Blattner Energy to provide the civil and electrical engineering design for Phase 2 of Alamo Solar. Westwood’s experience on this phase led to involvement with phases 3 through 5, which were built by Mortenson Construction.

Different Equipment on Phases Requires Careful Design

Each phase of Alamo Solar has presented unique engineering challenges. The civil grading design process was complex due to the tight tolerances driven by the solar tracking equipment requirements. The electrical engineering process required balancing multiple variables as a result of using different solar technologies and equipment on each phase of the project. The unique properties and requirements of the various equipment types required careful design and change management.

The variation in solar tracking equipment on respective phases of the project posed a preeminent challenge. Ercam dual axis trackers were used on phases 2 and 4 of the project. This tracker is unique because it utilizes hydraulic pumps to tilt the rows and modules, with one pump for every four rows. Furthermore, panels are mounted on a linear beam tracker, which tilts the modules east-west and north-south. This is unlike a standard dual axis tracker, in which a panel of modules is mounted on a single post with motor-activated tracking. Ercam trackers have specific construction tolerances that must be met to ensure proper operation. Proper civil grading design, as well as layout of the arrays, was critical to meet the necessary construction tolerances and to prevent any shading between solar modules and tracker rows. Westwood worked closely with the contractor to produce the best design possible given the equipment properties, site constraints, and intended construction methods.

A Paru/SunAction tracker was used on phases 3 and 5 of the project. These trackers, originally manufactured for the foreign markets, were not designed to American UL standards. This equipment characteristic created an atypical electrical engineering design parameter for the project. The solution was to tie partial strings together across three trackers to create a single string. Arriving at this solution required engineering flexibility and openness to exploring creative solutions.

The Alamo Solar project, in its entirety, represents a significant achievement for the U.S. PV solar industry and the developers, contractors, and engineers that support it. Westwood is honored to contribute to the operational and ongoing phases of the project through thoughtful, inventive, and effective engineering design.