UTR-20 Assembly Instructions

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ABOUT TRACKERS
The UTR-Series Tracker is an ingenious and economical way to increase photovoltaic efficiency an average of
25%. Photovoltaic panels mounted on a tracker will be much more efficient than the same panels mounted on a
fixed rack when the tracker follows the sun for at least 6 hours a day. Because a tracker relies on a differential
of solar heat gain in the canisters, it will react quicker on a bright sunny day than it will on a partially cloudy
day.
CHOOSING A LOCATION
Choose a location where the tracker will receive the sun all day. Clear exposure throughout the day with an
unobstructed and clear view of the sun is required. Locate the Track Rack™ where it will receive the earliest
morning sun. The rack needs the early morning sun to “wake up”, or return to the eastern position, so it is
important to place your Track Rack™ where it won’t be shaded in the morning by structures, poles, trees,
bushes, etc. Remember that the sun rises and sets north of true east /west in the summer and south in the winter.
You will be able to adjust your Track Rack™ for the winter & summer solstice accordingly.
TRACKER OPERATION
The Track Rack™ is moved by the shifting weight of the liquid refrigerant from the east or west canisters
through the copper transfer tube located at the south side of the assembly. The aluminum “shadow plates”
shade the canister closest to the sun. The other canister grows warmer and shifts the weight to the cooler
canister, tilting the Track Rack™ until it points exactly at the sun and shades the canisters equally. The tracker
will not track without the shadow plates.
TOTAL TRAVEL
The rack is designed to travel through a 90° arc and is still very effective down to 60° of rotation. A Track
Rack™ is only stable if the axle is above the center of gravity. If the axle is below the center of gravity, the
Track Rack™ will be unstable. Even in calm, sunny weather it will be hunting for, but overshooting, the sun.
To make the tracker stable, lower the center of gravity by moving the counterweight down. A Track Rack™
with its center of gravity perfectly adjusted will reach its stop in the afternoon at about the same time all the
refrigerant has moved to the west canister. It should not strain hard against the bumper stops. If the center of
gravity is too low the tracker won’t turn all the way to the bumper stops. If the center of gravity is too high the
tracker will be unstable in the wind. There is broad latitude of adjustment that works for most Trackers.
SHOCKS AND THE BUMPER STOPS
The shock absorber is the first line of defense for the Track Rack™ against wind. It’s meant to prevent sudden
gusts from pushing the rack off course, as well as restricting any violent movement that may harm the rack and
modules. The shocks yield to a constant force by design, thus promoting tracking and, as a result, will be
affected in a constant wind-loading situation. The bumper stop is the second failsafe in the structure. It prevents
any catastrophic failure from occurring by limiting the overall travel of the Track Rack™.