Inclinometers for Solar Tracking Systems0 pages

Absolute inclinometers prove 
advantageous in solar 
tracking systems   
Misconception #1: Our systems use calculations based on the sun’s location and this
formula is built into our tracker module so there is no need for an inclinometer.
Response: The algorithm (software program) is actually needed as a part of a closed
loop measuring system. But without an absolute measuring device such as an
inclinometer (gravity based tilt sensing device) you really don’t know if the actual solar
collector (be it module or panel) is really pointing in the right direction. The algorithm tells
one where to point… the inclinometer says that yes indeed, you are actually pointing
there. One can think of the algorithm as a map and the inclinometer as feet on the
ground giving feedback.
There are conditions that can affect whether or not the solar collector is pointing properly
and an open loop system is not able to detect this condition. The items that affect an
open loop system can be corrected in a closed loop system as follows:
Seismic movement of the solar collector/foundation: A good utility scale solar
generator should be designed for at least a twenty year life, however over this life, things
can happen. If the system simply drives the collector X amount of steps or counts, the
position is simply inferred and not known. On the other hand, an inclinometer positioned
on the collector gives the system an absolute position.
Wind buffeting: Utility scale solar collectors are large devices in which prevailing
winds can induce mechanical and angular offsets and if there is not an absolute sensor
(aka gravity based inclinometer) indicating the true angle, then these offsets can affect
the angular position. Again, an open loop system with no feedback cannot compensate
for the prevailing wind condition.
Lost transmission data: Sometimes data transmission can get corrupted or lost.
Having an inclinometer onboard serves (as mentioned above), as a checking standard
for knowing if you are pointing where you want to be pointing.
Lost power: This condition is very similar to lost transmission data. If there is no
checking standard, such as an inclinometer to give feedback, then under a lost power
scenario the system must be recalibrated, thus causing lost operational time. This might
be done by going back to stow position and setting off reset switches, etc. The use of an
inclinometer gives the absolute angular position as soon as power is returned. No need
to reset the systems, therefore eliminating the need for expensive recalibration.