The Structural Engineering Institute (SEI) of the American Society of Civil Engineers (ASCE) recently approved the establishment of a new committee whose purpose is to provide guidance to the solar industry in the design, development, and construction of solar photovoltaic (PV) structures. .
This committee is called the Solar Photovoltaic Structure Committee and is composed of engineers, manufacturers, contractors, licensing officials and owners. The task of the committee is to focus on the structural and geotechnical design of the unique structures that support photovoltaic modules on building roofs, garages and ground-mounted facilities so that these structures are always reliable and economical across the country.
For the inexperienced, the design of photovoltaic structures is simple and can be well understood by the engineers and manufacturers who design and build them. However, the reality is that the rack supporting photovoltaic modules is a unique structure. Current structural design standards and building codes usually take into account traditional bridges and buildings, which are not enough to make the solar industry reliable and economical. .
The fixed inclined shelf was damaged due to a wind incident.
The continued push for savings in photovoltaic installations drives the demand for detailed design guidance in the photovoltaic industry, as the benefits of “pencil sharpening” can be huge. In large utility projects, structural elements are repeated thousands of times, and optimizing these elements can save a lot of cost.
For example, in a 200 MW project, it is easy to have 100,000 piles. Reducing the length of the pile from 15 feet to 13 feet can save millions of dollars. However, to properly test the rationality of this optimized pile length requires a thorough understanding of the behavior of the PV frame structure system under all load conditions, and all stakeholders agree on the acceptable risk of failure and the cost required to reduce the level of risk.
Without a reliable and consistent method to design these types of structures, the solar industry will continue to struggle with flaws, misunderstandings, inconsistent designs, and potential lawsuits.
Antifreeze roof (ascending) on photovoltaic structure. The
Committee strives to become a stage for cooperation and the exchange of experiences and lessons in the photovoltaic industry, so that everyone can benefit. This can be challenging, but better understanding the behavior of photovoltaic structural elements requires collaboration. Buildings and bridges have decades of experience and research that can be used in their design, whereas photovoltaic structures cannot.
For ground-mounted photovoltaic structures, no formal industry guidelines are provided to engineers on how to reliably and consistently design them. In the absence of a design guide, engineers will do their best within the limits of the project schedule and budget. This often leads to inconsistent and / or unreliable designs. This new committee hopes to fill this knowledge gap and provide the guidance the industry is looking for.
The committee is currently cooperating on important issues such as wind load, snow load, corrosion, frozen pile top (lift), pile testing and PV specific reliability indicators.
is currently formulating the ASCE Professional Practice Manual, and then detailed industry design standards will be developed. The committee plans to publish updates and best practice articles so that solar PV structural and geotechnical engineers can begin to implement consistent and reliable designs. Please continue to pay attention to future articles on the progress of structural and geotechnical design of solar photovoltaic structures.
Jon Manning is a structural engineer at Kimley Horn. Steve Gartner is the chair of the new ASCE Solar Photovoltaic Structures Committee and a senior structural engineer for HDR. They are both located in Minnesota.