POWER June 2022 - 30

SOLAR POWER
Solar Power Plant Maintenance
with Thermal UAV Inspection
Technology
Thermal imaging is a vital tool for detecting defects and anomalies at solar power plants.
However, capturing thermal images with handheld equipment is time-consuming and
susceptible to human error. Unmanned aerial vehicles with dual-camera attachments
flying on preprogrammed routes provide a precise and repeatable way to complete
inspections efficiently.
Cheng Hong Tsai and
Jie-Ming Yang
A
s a cleaner form of energy, solar
power generation relies on several
major components including
photovoltaic (PV) modules, highvoltage
power equipment, inverters,
power cables, and direct current-alternating
current (DC-AC) string boxes.
To ensure smooth power generation,
the equipment requires proper maintenance
so that everything works well.
Equipment inspection is an important
part of the process.
There are three types of common
anomalies in solar power generation:
PV module string anomalies; single
PV module anomalies and diode circuit
anomalies; and anomalies contributed
by environmental factors (such as
shadowing, biological contamination,
etc.). Some anomalies, such as PV
string anomalies and anomalies contributed
by environmental factors, can
either be detected by observing an increased
or decreased amount of power
generated, as shown on the monitoring
system, or they can be detected visually.
Some anomalies such as single
PV module anomalies or diode circuit
anomalies, on the other hand, cannot
be detected through such means. In either
case, thermal imaging is an ideal
tool for inspection, as anomalies can
be precisely located through this method
and repaired.
Thermal Imaging
Thermal imaging works by turning the
infrared radiation detected from an object
into electronic signals, which are
then processed into an image. It can
help locate anomalies in a solar power
plant because anomalies on a PV module
show a difference in temperature.
30
Handheld thermal imaging tools
are commonly used for solar power
plant inspections. However, handheld
equipment suffers from a couple of
drawbacks.
Firstly,
it
is time-consuming to inspect
a large power plant area with a
handheld tool. Some areas might also
be missed during inspections. Handheld
thermal imaging tools are better suited
for inspections of smaller areas.
Secondly, there are safety concerns.
Many solar power plants are
not installed on the ground but rather
on rooftops or on water surfaces.
To capture clear pictures when using
thermal imaging tools, it is necessary
to keep the camera a certain distance
away from the equipment during the
inspection and while taking pictures.
Due to limited operative space on rooftops
and on water surfaces, inspecting
with handheld tools increases the
safety risks of the inspector.
Given such drawbacks, combining
unmanned aerial vehicles (UAVs)
with thermal imaging provides a
more efficient and safer alternative
for
inspections.
Maintenance
staff
can inspect more PV modules
within the same amount of time and
precisely locate anomalies without
increasing safety hazards. The following
sections will briefly introduce
the characteristics of thermal
imaging UAVs adopted by ECOVE, a
company experienced in solar power
plant maintenance, as well as some
real cases with images showing the
anomalies found during inspections
conducted across solar power plants
in Taiwan. To see many more images
from real-world inspections, read the
online version of this article at www.
powermag.com.
www.powermag.com
1. This thermal image shows an anomaly
from a single PV module string. Courtesy:
ECOVE
2. This thermal image shows an anomaly
from multiple PV module strings. Courtesy:
ECOVE
Thermal Imaging UAVs
The multi-axis UAV discussed here is
a customized dual-camera design that
can take thermal imagery and visible
light imagery. It can fly under 15 meter/
second wind conditions, with an 8 kilometer
maximum operation distance and
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POWER June 2022

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