By Daniel Sherwood, P.E., president and co-founder, PVComplete
As the number of single-axis tracker manufacturers has continued to grow and diversify, so too has choosing the optimal tracker technology for a given utility-scale solar project become ever-more complex.
One manufacturer may claim short rows are superior because they make it possible to fill every nook and cranny of a project site and better accommodate changing terrain. Another manufacturer might tout the advantages of longer rows and more robust designs as an advantage when it comes to fewer drive motors and less long-term maintenance. Separating fact from fiction and hype from real advantages has been a significant challenge.
Until now.
Advances in solar design software provide a data-driven analytical comparison of tracker technology on a site-by-site basis that cuts through the marketing hype to enable bankable decisions that mitigate risk and improve long-term project performance.
By leveraging modern cloud computing and data analytics, leading solar software platforms are able to generate project layouts for tracker projects of any size in minutes. This new speed and accuracy makes it possible to produce side-by-side layout comparisons of project designs featuring different tracker systems that reveal key decision metrics such as:
- The amount of steel required by each system
- Which manufacturers are best suited to the complexities of a given site and able to maximize rackable area by filling in corners, going around bends, hugging farmers’ fields, following the contours of hills, conforming to the boundaries of cloverleaf highways or circumventing wetlands, waterways and other obstructions
- The number of motors required for each system, providing a better forecast of maintenance requirements and possible points of failure
- Precise computations of ground coverage ratio (GCR), kW output capacity and production values
- Anticipated foundation installation requirements
Personal biases in favor of industry incumbents vs. newcomers, centralized vs. distributed architecture, long vs. short row lengths and more can be replaced by data-supported evidence of product suitability. With side-by-side design comparisons, the pressure to identify a universally accepted tracker can be replaced by an opportunity to assess the best tracker for every unique project, improving project outcomes.
For example in Figure 1, we see a 13.6-MW tracker layout with 90 module rows in square, standard blocks. In this example, using a driveline to drive multiple rows with a single motor can greatly reduce the motor count and therefore the complexity of the EBOS. It also presents far fewer points of failure for plant operations and maintenance.
Figure 1: 13.6 MW using 90 module rows, drivelines shown in red.
Figure 2 shows the same 13.6 MW system with a broken up layout. Using linked rows of 90 and 60 modules will still reduce the motor count, but not nearly as much as in the first example. Also, using shorter tracker rows of 30 modules per row will allow more than 17 MW to fit on the same site, as shown in Figure 3.
Figure 2: The same 13.6 MW in a broken up configuration doubles the number of drivelines.
Figure 3: Using a tracker with only 30 modules per row allows 17 MW on the same site.
Another thing to consider when choosing the best tracker is topography. Longer tracker rows are typically not well suited to slopes and varied terrain. For example, Figure 4 shows a group of 90 module row trackers modeled on top of topography. The piers in the middle section would need to be more than 10 feet tall in order to keep the tracker row in the same plane. This is impractical and would cause the foundation to fail structurally due to the torsion force. Also, because the center of the trackers is misaligned, a single driveline cannot be used. By comparison, using 30 module rows, as shown in Figure 5, allows the piers to remain well within spec.
Figure 4: 90-module rows, modeled on terrain. The middle piles are too tall and will fail structurally.
Figure 5: Using shorter 30-module rows will allow the tracker to be installed over the topography without issue.
Examples like these reveal just a few of the side-by-side tracker comparisons that advanced software now enables. With analytical evidence easily accessible, project engineers are able to identify the best solution for each unique project site, improving bankability and ensuring greater overall utility-scale project outcomes.
Daniel Sherwood, P.E., is president and co-founder of solar design software company, PVComplete. PVComplete’s PVCAD Mega software delivers utility-scale tracker and fixed tilt layouts in minutes, with CAD precision. Over the course of the last two decades, Daniel has designed hundreds of solar projects and renewable energy products.
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