The word “mount” is commonly used to describe how a solar array is set up, and the two main types are roof-mounted and ground-mounted arrays. While the use of this word can create the impression that a solar-generating system is a static, non-moving thing, our AllEarth Solar Trackers defy that preconception, as they physically move, using GPS technology to follow the sun from sunrise to sunset throughout the day.
If you catch your tracker in a flat, horizontally oriented position, you may easily think something like, “my tracker’s not working!” Chances are very high, however, that it’s working exactly as it should. If it has been particularly windy or cold, your tracker is likely in “Wind Hold Mode” or “Cold Mode.” Our AllEarth dual-axis solar trackers are equipped with a control box and wind sensor (anemometer) which are used to keep track of the surrounding wind speeds and temperature, activating “Wind Hold Mode” or “Cold Mode” when needed.
Wind Hold Mode is triggered when the wind sensor recognizes wind speeds exceeding 25 mph for 5 seconds. At this point, the tracker goes into a horizontal “stow” position to protect itself from the high winds, in the same way we’d seek shelter when outside during a storm. Even during wind hold, the tracker will continue to produce energy.
Cold Mode, on the other hand, is activated to protect the solar tracker’s hydraulic power unit (HPU) which is responsible for moving the solar array. Arctic temperatures can potentially exert strain on hydraulic components and may temporarily reduce tracking accuracy. To reduce this risk, the tracker enters Cold Mode in extreme, sub-zero temperatures.
In late December of 2022 and early February of 2023, Vermont experienced brief but intense bouts of these arctic temperatures. Many of our trackers went into Cold Mode, assisting them in enduring the harsh weather conditions. In Cold Mode the tracker will go into the horizontal stow position. When temperatures warm up to around 0 degrees Fahrenheit, the tracker will rotate and tilt into position and resume normal operation.
Just as in Wind Hold Mode, the tracker continues to produce when in Cold Mode. Production will be reduced during this period, depending on weather conditions, but the time during a year that a tracker is commonly in code mode is very short, so the overall impact this has on total production during a year is minimal.
In fact, another positive of trackers being flat on days with clouds (low sun intensity) is that they can produce more energy from the diffuse sunlight. Pointing straight up captures a larger area of low energy sunlight. The tracker’s blend of sophistication and reliability is what allows a tracker to achieve significant gains in efficiency when compared with fixed roof or ground-mounted systems. It’s also what gives a tracker some of its personality and life. But along with this complexity comes the need to preserve and protect that producing capacity during extreme weather conditions. As humans, we do things like bundling up in warm clothes, sitting next to a fire, gathering indoors, etc., to insulate ourselves from the cold and wind. Our trackers are designed to protect themselves as well by using these two modes. Between these built-in functions and an active O&M (Operations & Maintenance) agreement from AllEarth, your tracker is well insured for the long term.