IEC Corporation completed a structural review for the Algonquin SKIC20 Solar Project in Bakersfield, California -- a 20 MW solar farm on 167 acres. The Client, Algonquin Power Co., was concerned that the structural integrity might not be adequate for a 100-year extreme wind event (including the wind design requirements of the California Building Code) when the panels are at their most extreme angle under a power failure condition. In addition, Algonquin requested a recommendation on the need for backup power supply to return the panels to the horizontal position during a power outage.
IEC conducted an independent engineering study of the racking system to evaluate the existing design and its ability to withstand the extreme wind conditions. IEC's structural engineer determined the appropriate Design Criteria for the site and the solar racking system and verified that against the existing design package. IEC also determined critical load cases (four basic cases, with three variations each). IEC team checked the rack framing members for critical load cases and compared that to Allowable Stresses to verify that existing members were adequately sized. IEC also checked the stability of the racking system in both the "short" and "long" directions, reviewed anchorage requirements for each component within the racking system, and reviewed foundation requirements for each critical load case to verify that existing footings were adequate.