Inspecting roof-mounted solar panels with thermal imaging

Paul Boughton

Over time solar panels can develop defects which can cause a severe drop in energy production and in some cases start a fire if left unchecked.

Defects can be easily remedied if detected on time, and that is why more and more solar panel installers are carrying out regular inspections using thermal imaging cameras to ensure the safety and effective deployment of solar systems.

Thermal imaging cameras can be used to detect hot spots in the panels from a distance, which makes it a lot easier to find defects before they become breakdowns.

Italian solar panel installation company ELEM srl is working with SAS di Ermoni Alberto e C - a thermography inspection agency with decades of experience with thermography.

One of its inspectors Alberto Ermoni, a Level II certified thermographer, says: “Thermal imaging cameras from FLIR Systems are the ideal tool for the inspection of solar panels. This inspection method is non-destructive and non-invasive.You can use thermal imaging to inspect the solar panels under load, so no shutdown is required. Thermal imaging cameras show accurate temperature differences between cells or within a single cell to identify faults in an early stage.”

Inspections are not limited to the solar panels: “We use thermal imaging to inspect the entire system, from the solar panels to connections, inverters, fuses and all other electrical components in the system,” explains Ermoni. “If any part of the systems starts to wear down or develops a higher resistance, the corresponding increase in temperature can be detected very easily with a thermal imaging camera, so you can fix the problem before the system fails.”

The thermal imaging camera used for these inspections is the FLIR T640bx.

“This camera combines top notch image quality with advanced features like wireless WiFi connectivity with a Tablet PC and a wireless Bluetooth connection to selected Extech test and measurement tools with the MeterLink feature, such as the Extech EX845 clamp meter. Another feature that I use often is the Picture-in-Picture feature. This overlay of a thermal image over the visual image allows me to better localize hot spots.”

The FLIR T640bx thermal imaging camera contains a microbolometer detector that produces thermal images with a resolution of 640x480 pixels and at a thermal sensitivity of 35mK (0.035°C). With its bright LCD screen and viewfinder it operates well, even in sunny conditions. The wireless WiFi connection from camera to a Tablet, PC or smartphone running the FLIR Viewer App makes it easy to show inspection results to clients on site and allows us to produce reports on location.

The MeterLink connection over Bluetooth allows the FLIR thermal imaging camera to automatically embed measurements from selected Extech measurement devices with the MeterLink feature, making hard copy measurements redundant. This not only speeds up inspections, it also reduces the risk of human errors.

One other very important factor in Ermoni’s choice of the FLIR T640bx thermal imaging camera is the fact that it has interchangeable lenses. “In some cases you are standing on a raised platform inspecting solar panels from a distance of 10 metres, but in another situation you might be inspecting the back end of panels from less than one meter distance. In these different situations you need different optics, a telephoto lens for the inspection from a distance and a wide angle lens for the short distance inspections. Many other thermal imaging camera models do not feature this flexibility in optics.”

For more information, visit