Data-Driven Design for Mounting and Racking Systems

Utility-scale solar mounting and racking system design is a delicate balancing act of building for site conditions while ensuring cost effectiveness for the client, maximum energy output for the end user, and healthy returns for investors.

Given North America’s varying landscapes and climate zones, each solar project presents its own unique design challenges. No design is the same, but a holistic approach should always be the main guiding principle.

Focusing on the big picture accounts for complexities, informs a successful design to produce maximum energy output for the communities we serve, and a financial return for investors. Examining data, weather patterns, and geographic challenges, and gathering information from landowners, are all crucial aspects of the design process.

Design decisions impact the entirety of a solar facility’s performance and its longevity. When you consider the entire system cost, capital investment, downtime, repair cost, and Integrated Subsystem-System Performance Analysis (ISSPA), a megawatt hour is cheaper in the long run.

Leveraging the power of data

When it comes to utility-scale solar mounting and racking system design, data is the single source of truth. With the right data, we can understand how various systems perform and drive decision making to execute our projects with precision. Data can make our products better, helping us to provide sound advice to our clients that’s backed by scientific evidence.

Each project requires special consideration. Data offers irrefutable facts that guide billions of calculations, and provides the precision required to ensure the stability, efficiency, and longevity of a solar power installation.

Examining weather trends to shape solar designs

While they’re driven by math and science, engineers are also historians; they predict the future by examining the past. This includes a comprehensive examination of local weather patterns over the past 25 years (including sun exposure) to maximize the potential of the solar panels. It also includes considerations for:

• Wind

The biggest risk for mounting and racking system design is wind. Fixed tracking systems face the wind regardless of speed. Most single- or dual-axis tracking systems have wind gust sensors, allowing them go into a stowed position to become more aerodynamic.

Fixed racking systems are supposed to deliver about 20 percent less energy than a single- or dual-axis tracker system. If designed right, however, they can produce a lower cost of electricity in some situations, when evaluated in an ISSPA that includes all factors.

• Temperature

Cold weather and frost-susceptible soil affect the design’s pile foundation. Ensuring trackers don’t heave requires either helical piles with plates buried below the frost line, or alternative frost-resistant pile designs. In some cases, with trackers spanning the length of a city block, the steel experiences maximum expansion and contraction due to temperature extremes. Attention must be paid to torque tube movement to ensure there’s no mechanical interference that could lead to an overworked drive motor, mechanical binding, and eventual failure.

Closely examining historical trends and layering them on top of other drawings ensures that proper care and attention is given to the history and patterns of the land; these are best understood by long-term landowners. Understanding the probability of weather events mitigates risk and optimizes site performance.

Leveraging historical insights and community knowledge

If lessons learned from the past aren’t applied to future designs, history is bound to repeat itself — one piece of data often overlooked during the design process is the perspective of the local community and landowners.

Local conditions at solar sites aren’t always what people from urban centers think they are. Collecting historical narratives about the site from those who live there and have firsthand experience reduces potential blind spots in the raw data. The oral history helps inform robust data for the design, and is something that can be used in discussions with the client to help them fully understand the benefits of proposed design characteristics.

Renewable expansion: balancing solar power and urban growth

As urban centers expand to accommodate growing populations, the demand for power and the diversification of energy supplies increases. It's crucial to position power sources nearby, but not so close that they impede city development.  

Flat desert sites are ideal for a utility-scale solar solution, but many are either already in use or too far away from the grid. On the other hand, hilly sites with fluctuating terrain are challenging to build on but, in many cases, exist in an ideal zone. 

As we become increasingly dependent on renewable energy, engineering and design play an invaluable role in overcoming geographical challenges and delivering the right solutions to meet the needs of the communities we serve.

Walter Schachtschneider has more than 40 years of experience in the construction industry. He leads a team of high-performing engineers in PCL Construction’s Solar division. Walter and his team specialize in optimizing solar facilities to determine the lowest levelized cost of energy and design management. His team solves complex technical issues, and conducts remote commissioning, and performance monitoring and reporting.

PCL Construction | www.pcl.com