An Optimized Target Reliability Index for Solar PV Structures Considering Excess Mortality due to Structural Failure-Related Power Outage

An economical and tactical transition to renewable energy sources is critical for social welfare and national security. Construction of utility-scale solar photovoltaic (PV) plants is accelerating this transition. Solar PV structural behavior differs from typical building behavior in many ways. However, these structures are designed under the prescriptive provisions of existing building codes that do not recognize, or account for, the unique characteristics and risks associated with solar PV structures. The motivation for this study is to calculate an optimal solar-specific reliability index and compare it to the existing building code reliability targets to either validate or to suggest improvements to current structural design practice. The methodology involves application of a recently published target reliability index procedure where cost optimization and human safety are considered separately. This approach also permits the unique life safety implications of utility-scale solar PV plants to be explicitly captured by the reliability index and, therefore, the structural design. There are no occupant-related life safety risks associated with utility-scale solar PV plants. However, there is a power generation function life safety risk. That risk is captured herein as excess mortality due to solar PV structural failure-related power outage. The resulting solar-specific reliability index is then compared with the current prescriptive building code reliability targets. The results demonstrate that for the current inventory of utility-scale solar PV plants, the prescriptive building code reliability targets are excessively conservative. The provisions require a structural safety expenditure that does not result in measurable increases to social welfare. The associated cost penalties decelerate the transition to renewable energy by limiting the scope and scale of new solar infrastructure investment. The advantages commensurate with the solar-specific reliability indices presented in this paper can be captured by applying the performance-based procedures in the existing building codes to solar PV structures. This approach includes flexibility to adjust the solar-specific reliability indices proportional to the national inventory size and individual project scale as the transition progresses, thus, promoting the fastest transition to renewable energy with explicit management of life safety risk, while ensuring economy, social welfare, and national security.