Historically, the land used for utility-scale solar farms has needed to be graded extensively to establish a smooth, level surface. This allows for proper alignment of solar panels and solar trackers to maximize the panels’ orientation toward the sun. However, such grading is labor-intensive, disrupts the natural landscape, and substantially increases both the carbon footprint and cost of a new installation.

Enter the terrain-following tracker, a solar tracking system specifically designed to function on uneven or sloped terrain. By conforming to the natural contours of the land, terrain-following trackers maximize the energy captured by solar panels, significantly reducing grading requirements by up to 90%.

Terrain-following tracker technology is not new; it was introduced in the 2010s by innovative manufacturers aiming to broaden the range and suitability of sites for solar projects. However, initial adoption was slow due to developers' preference for flatland installations and the higher initial costs associated with the technology. These days, such lackluster adoption is turning around.

The Tipping Point

More than half of the solar design projects in the 2024 portfolio at Burns & McDonnell now incorporate terrain-following trackers, marking a significant increase from their rare usage just a year earlier. This growing popularity, especially on larger-scale projects exceeding 200 megawatts (MW), can be attributed to several factors:

• Lower costs. On larger installations that require extensive grading, terrain-following trackers now can offer a more favorable value proposition compared to traditional solar farm construction methods on many projects. A cost analysis considering installation size, terrain complexity, labor costs and other project-specific factors can be leveraged to make this determination. For two solar projects now under construction by Burns & McDonnell in Illinois and Michigan, for example, the cost analysis showed that grading expenses would exceed the acquisition and installation costs of terrain-following tracking equipment. In both cases, using terrain-following trackers will reduce the amount of earth moved from more than 250,000 cubic yards to less than 50,000 cubic yards. Additionally, the use of these trackers decreases the installation time spent by crews in the field.
• Greater sustainability. Bulldozers and other heavy equipment used to level solar sites and seed groundcover consume significant amounts of diesel fuel and leave a sizable carbon footprint. And by minimizing the civil work required, terrain-following trackers can potentially reduce the amount of steel needed for support infrastructure, resulting in more sustainable solar installations.
• Fewer environmental risks. A site's topography reflects the weather events and geological processes that shaped it. By preserving the natural landscape, terrain-following trackers help maintain existing site drainage patterns — minimizing erosion and stabilization risks, as natural water flows follow their original paths.

Impact on Site Considerations

Commercial solar farms are typically built on farmland chosen for its smooth terrain and favorable landscape — both well-suited for farming. Many prime locations in Texas, the South and the Southwest have already been converted to solar farms, prompting developers to explore more opportunities in the Midwest, where demand for renewable energy is growing and land availability is often greater.

When considering options, developers should factor in the potential use of terrain-following trackers. It is crucial to understand the capabilities and operational limits of the terrain-following trackers currently on the market. For instance, a location should not exceed the slope tolerance of the terrain-following tracking technology. Today's technologies are better suited for rolling hills with gradual grade changes than steep mountainsides.

Survey accuracy is particularly crucial for solar projects using terrain-following trackers. In traditional installations, developers can collect new data after leveling is complete. However, in projects with minimal or no grading, there are no "second chance" surveys since the grading is largely eliminated. Conducting a comprehensive study of the existing topography, including water concentration and flow patterns, can significantly inform the design process.

The Bottom Line

Because single-axis terrain-following trackers have the flexibility to follow the natural grade of a site, they reduce the need for extensive grading and mitigate many of the risks associated with erosion, ground disturbances and construction.

The cost savings and reduced carbon footprint associated with terrain-following trackers are now tipping the scales in their favor among solar project developers and engineer-procure-construct (EPC) contractors. However, successful implementation hinges on understanding the topographic variables specific to each solar project. A terrain-following tracking solution should not only address these variables but also align with the developer’s financial objectives, risk tolerance and sustainability goals.