Fixed-tilt racking still has a place in utility-scale solar

Single-axis solar trackers have become the dominant structural choice for large-scale solar construction in the United States, but there are scenarios where using fixed-tilt racking still makes the most sense.  

Solar trackers have the advantage of generating more energy by pointing modules toward the sun. Mobile racking was installed in more than half of U.S. utility-scale solar projects starting in 2017, according to the U.S. Energy Information Administration. 

American tracker manufacturers have stepped up to fulfill the domestic demand. U.S. manufacturers produced 37 GWDC of solar trackers in 2023, a year where 32.4 GWDC of new solar was built in the country. 

Fixed-tilt remains popular among ground-mounted projects in the distributed generation market and is still a viable racking choice for utility-scale arrays. It’s ideal for environments where trackers might falter — in high winds, heavy snow loads and steep topographies.

The lack of moving parts makes fixed-tilt more suited to regions with extreme wind conditions, like the hurricane-prone Southeast. Trackers are programmed to stow module rows flat to reduce resistance in high winds, which could negate the benefits of these more expensive mounting options if it’s happening too much.  

“A lot of times, in order to accommodate those conditions, you’re not really tracking anymore, so you’re not getting the benefit of the tracker,” said Dave Wilson, director of engineering at OMCO Solar, a fixed-tilt and solar tracker manufacturer. “You’re essentially a fixed-tilt system during those conditions.”

While trackers are making strides in adapting to uneven landscapes, fixed-tilt racking has a longer history of working on these sites. Each fixed-tilt unit is relatively small and can angle panel bays at shorter intervals than a tracker. Having higher slope tolerances reduces the grading necessary to prepare a solar project site, as well — a costly prospect in solar construction. 

Additionally, standard fixed-tilt models are more lightweight than trackers, meaning fixed-tilt can be deployed in tougher soil conditions, like rock and sand, while requiring less engineering for foundations. Trackers have adopted specialized foundations like ground screws and helical piles to ensure they still work in those conditions. But in the solar market, they originated in fixed-tilt construction. 

“There is a lot of different loads that go into a tracker,” said Josh Von Deylen, CEO of APA Solar Racking. “It is a moving piece, so when you get into some poor soil conditions, like very soft soils, maybe a helical foundation with a fixed-tilt solution is a much better option.”

Fixed-tilt can also be installed at higher system density than trackers. Tracker arrays must account for inter-row shading, when one solar module row casts shade on another. By reducing panel angles and tightening rows, fixed-tilt projects can significantly increase their generation without the worry of shade, all while using less land.

Fixed-tilt costs 

Fixed-tilt racking costs less to manufacture than trackers thanks to fewer components involved. The simpler design results in fewer truckloads of racking components to sites and less specialized labor requirements on install days. 

“If the labor rate is low, you might not care as much. If the labor rate is high, and if there’s prevailing wages driving the labor rates up, or you’re in some part of the U.S. that has high labor rates, that goes into the mix as well, and that pushes it toward fixed,” said Matt Kesler, director of solar technology at OMCO Solar. 

Using fixed-tilt racking reduces the level of operations and maintenance required on a project post-construction too. With no parts to keep moving, O&M duties shift to upkeep of the site itself and electrical components.

Trackers will likely stay the popular choice for utility-scale solar projects. However, when the wind is too strong, the land is too uneven or the cost is too much, fixed-tilt racking could be the right fit.