Solar Racks, Tracking

Solar Tracking Racks are mounting structures that physically move to follow the sun as it passes through the sky. In many cases this results in more "peak sun" hours and a larger energy harvest on a given day, in comparison to a stationary array.

Depending on the design, the movement of the array can be passive or active(using motors and electronics). All tracking systems move on the East-West axis to follow the sun from dawn to dusk (single-axis). A single-axis tracker requires manual azimuth adjustment on a seasonal basis to closely match the elevation of the sun at various times of the year. Dual-axis trackers automatically adjust the array's azimuth to match the sun's elevation.

Solar arrays can be heavy, and so the tracking rack often has to manage the difficult job of reliably moving the array under harsh environmental conditions. Wind, rain, snow and temperature extremes all take a toll on any mechanical device that is constantly exposed to the elements, so keep that factor in mind before buying a tracking array, especially an active tracker. Weigh the additional electrical harvest against the increased maintenance and cost to arrive at a good decision that meets your needs.

Tracking arrays can be especially beneficial for remote water pumping installations, where the total energy harvest is less important than the total number of "peak sun" hours per day. A water pumping installation with a tracker will produce a lot more water on the average when using a solar tracking array.

For residential off-grid installations in northern latitudes, a tracking array may be of less overall benefit. That is because in the winter (when solar harvest is in short supply), the sun takes a very short arc across the sky from dawn to dusk and a tracking array offers no substantial benefit. It is usually wiser to invest your money into a larger solar array instead of a tracking rack because the larger array will harvest more energy in winter when days are shorter and energy usage is generally higher, while the tracker will only benefit the longer days of the year.

The situation can be quite different in lower latitudes and hot climates, where energy usage may be higher in summer (for air conditioning), and in wintertime the sun's arc across the sky is longer. For example, folks in the Southwest US can benefit substantially from solar tracking arrays, especially when the horizon is low and the sun is visible for more hours of the day. Do keep in mind however that trackers are generally more susceptible to wind damage simply because they have moving parts.