Solution
After a change in tracker racking vendors, Burns & McDonnell provided guidance as owner’s engineer on design options to mitigate the very real possibility of early failure of the solar module support system. Additional studies included a review of cathodic protection systems as well as various configurations for the rack system.
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Solution
After a change in tracker racking vendors, Burns & McDonnell provided guidance as owner’s engineer on design options to mitigate the very real possibility of early failure of the solar module support system. Additional studies included a review of cathodic protection systems as well as various configurations for the rack system.
As owner’s engineer, design solutions were reviewed to assess effectiveness in mitigating early failure of the module tracker system. After reviewing options for cathodic protection — a technique in which corrosion of the metal surface is controlled by making it the cathode of an electrochemical cell — that approach was rejected due to high cost. The preferred solution was to fabricate the pile foundations with an additional sacrificial metal surface that could degrade over time while protecting the structural integrity of the inner metal posts.
In addition, options were explored to provide heating elements to keep the trackers operating during ultracold temperatures, but ultimately were rejected as being too energy intensive. The trackers were instead designed with control logic that stowed the system so that the panel trackers would remain stationary during periods of extreme cold or when drifting snow covers the module surfaces.
As owner’s engineer, the project scope included:
- Review at 30% design
- Review at 75% design
- Engineering studies review
- Issued-for-construction (IFC) document and design review
- Compliance monitoring of the testing and execution plan
- Response coordination for requests for information (RFIs)
- Factory acceptance test observance
- Utility coordination support
- Site visits for:
- First-in-place reviews
- Installation quality checks
- Mechanical completion walk downs
- Commissioning oversight
The solar plant is interconnected to the regional grid via a 25-kV distribution circuit running from the local utility’s substation.
Results
The Suffield solar installation was successfully completed and commissioned in the fall of 2020 and was fully operational in time for the following winter season. The battery system providing power needed to move the module tracking mechanisms performed as designed during more moderate temperatures and stowed the modules to stationary positions when necessitated by high snow events and extremely low temperatures.
