All solar trackers are not created equally
Solar tracker architectures are very different in multiple ways. One important difference is how they are designed to handle structural wind and snow loads: for utilities looking for the lowest cost of ownership, selecting trackers that are robust and reliable enough to withstand inclement weather without failing over their 30-year lifespan is imperative. It’s for that reason that Array Technologies Inc. (ATI) – leveraging what it has learned from 27 years of solar tracker operation – applies engineered simplicity to the design of its trackers. ATI’s philosophy is to create a system where owners “set it and forget it” by minimizing system structural damage risk and long term maintenance costs. The company continues to focus on the evolution of its tracker technology to deliver utilities the lowest levelized cost of energy possible. “We have a very unique approach to mitigating wind,” said Ron Corio, founder and CEO of ATI. “It’s passive, and it doesn’t require battery backup.”
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ATI’s differentiator is that the module rows on its utility-scale solar trackers don’t stow in windy conditions for structural survivability. Instead, the trackers are carefully designed to withstand the wind in any position. “We have been providing products for risk-averse customers since day one, and we have never relied on a stow strategy for structural survivability,” says Thomas Conroy, president of ATI. “We build our systems to be structurally strong enough to withstand wind and all other specified structural loads. We don’t see any benefit to customers to take on all the risks involved in stow systems.” Why? Because, to ATI’s way of thinking, the increased risk involved isn’t worth the minor potential cost savings– and the fact that utilities deploy solar tracker systems to work for 30 years means that risk is something that should be avoided at all costs
Other tracker architectures rely on a stow system that theoretically lessens the impact of the wind. There are many sensing, control, and backup components that go into a solar tracker to be able to implement a stow strategy. If any one of these components fails, however, the tracker will not make it to stow position and is suddenly at high risk of structural damage should a wind event occur. First, there’s an anemometer that must sense the high wind event and trigger the system to go to stow. Second is the wireless signal that must be generated and sent. Third is the receiver that must receive that wireless signal. Fourth is the battery backup that must have a charge and be working correctly. Finally, the motor and inclinometer must both be functioning properly.
All of the described components have to work in series in order for the independently powered rows of a solar tracker to reach a flat stow position. If they don’t – if any of those components fail and the process doesn’t work – the result can be catastrophic. “They’re all links in a chain,” Corio said. “If you break one link, the system doesn’t do what it’s supposed to do in a mission-critical situation.” “We know from our experience that the owners of these projects are not interested in taking unnecessary risks,” Conroy said. “Thirty years is a long time, and one of the things I’ve learned in this industry is that anything that can happen in the field will happen in the field. That’s why we design our trackers the way we do.”
Another point of differentiation that informs ATI’s design philosophy involves the number of electronic and electromechanical parts and components, like motors and controllers, which make up its solar tracker systems. These components are critical because they are the most failure-prone parts of any tracking system, regardless of architecture. Here again, ATI employs the “less-is-more” approach that’s all about integration of function to minimize complexity and maximize reliability. “We recognized early on that a distributed motor design led to an extreme proliferation of the number of electronic and electromechanical components, which as any engineer can tell you negatively impacts system reliability, so we moved away from that architecture,” Conroy said.
The push-pull tracker architecture interestingly does not employ massive component counts, which makes them similarly easy to design and maintain, Conroy said. But those systems are structurally inefficient and complex to install. ATI’s systems, which use a linked rotating drive-line architecture, has dramatically fewer failure-sensitive components and requires less time to install, in part due to liberal tolerances designed into the system. “I’m an old power-gen guy, and when I hear people say ‘trackers are all the same,’ it reminds me of 35 years ago when we were starting up lots of coal plants,” Conroy said. “There were grate, then pulverized, then fluidized bed designs, all of which were significantly different design approaches with improved characteristics. The story of trackers and the differentiation of architectures has a similar sense of evolution to it. Some trackers, like ATI’s, are simply more reliable and deliver a better value.” “Our DNA is innovation, and that’s something that never stops,” Corio said. “The day we put out our version three tracker, we started working on engineering enhancements and changes we plan to incorporate. Our products always evolve.”
