Lisa Bell, !%FLIR Commercial Systems Inc.%!
Solar service and installation companies have known for some time that high-performance
thermal cameras, capable of detecting very small temperature differences and of
creating crystal clear images or video of problem areas, had enormous potential
to diagnose problems on solar installation sites.
Their drawback had been that they were prohibitively expensive
for smaller businesses. The past few years, however, have seen the cost of high-quality
thermal cameras drop dramatically, with models now available for less than $3000,
greatly expanding their use in building and maintenance applications, including
solar energy.
Innovative solar contractors are rapidly adding this tool to their
diagnostic and preventive maintenance programs. Pro-active thermal imaging surveys
of solar modules can identify problem areas quickly and efficiently, preventing
offline incidents and reducing operation costs.
In addition, solar contractors report that adding thermal images
and temperature data to inspection reports significantly increases the value of
these reports and generates more work opportunities.
Halcyon Solar Construction of Cottonwood, Calif., installs, maintains
and troubleshoots megawatt photovoltaic (PV) systems, both residential and
commercial. Co-owner Andrew Begley has been using a thermal imager to identify problem
areas in solar modules for more than a year – initially at the request of
a client familiar with the technology.
After renting a handheld thermal camera for close to a year and
becoming familiar with infrared technology and its possibilities, Begley was so
pleased with the results that his company purchased a camera at the start of this
year.
Thermal imaging is now a key component in Halcyon’s preventive
maintenance program. The camera, a Flir T300, offers extremely high quality images
and advanced features in an affordable, lightweight, tough and versatile handheld
package. Over the past three months, Halcyon has regularly used it to identify bad
modules and to mitigate system risk.
Halcyon Solar Contractors in California
uses a Flir T300 thermal imager to detect problems in solar cells. Top center, a
hot solar cell is revealed by thermal imaging. Top right, a hot splice box is found
at the back of a module where wires connect. Right, a solar module with broken glass
and damaged cells is imaged. Images courtesy of Flir Commercial Systems Inc.
Begley uses the camera to create a composite electrical reading
across the output curve of the entire solar module, to evaluate the quality of power
output, to identify bad connections and to understand overall thermal patterns,
including shading.
Thermal imagery can identify soiled or shaded individual cells
within the systems as hotter areas of resistance. In a photovoltaic installation,
efficiency is a function, in part, of temperature; cooler panels run more efficiently.
As individual cells fail, they can begin to heat up, rather than collect energy,
and this heat increase is easy to see with a thermal imaging device.
If a cell shows up hot in the thermal image but is not shaded
or soiled, Begley can zoom in for a closer look to pinpoint the problem. Common
defects in PV cells such as shunt or series resistance, or crystalline nonuniformities
can reduce efficiency – even shut down an installation.
Begley uses other industry-standard measures to confirm the potential
problems identified by the thermal imager, including current testing, voltage readings
and IV curve tracing. If the cell is found to be defective, Halcyon can replace
the solar module before it actually fails.
Halcyon’s camera includes both a thermal imager and a daylight
camera, with the onboard camera ability to fuse both types of images into a single
composite image that clearly shows customers where and what the problem is.
Advanced in-camera algorithms and preset temperature triggers
can quickly detect low and high temperatures as well as offer differential, or Delta-T,
readings. All temperature data, object parameters, voice and text comments are stored
with the infrared image, enabling advanced postprocessing and report writing.
Begley is particularly pleased with the data collection and reporting
functionality software analysis tools that complement and extend the use of his
thermal camera, including easy image organization tools and report templates. “I
can quickly and easily generate a complete report with images to show a client that
clearly identifies potential issues.”
Solar is a clean source of renewable energy, with essentially
free energy input and, as such, has tremendous environmental and political benefits.
However, to become a truly viable alternative, solar installations must achieve
the absolute maximum in production and performance. And as larger, more complex
and more numerous installations become more common, thermal imaging can help the
technology to reach its full potential.
Meet the author
Lisa Bell is a writer at Flir Commercial Systems Inc. in Wilsonville,
Ore.; e-mail: [email protected].