Infrared Imaging (or shortly: IR Imaging) refers in the solar PV industry to the termographic analysis of solar cells.
How does infrared imaging for solar panels work?
During IR-measurement the emitted heat radiation of the solar cells is detected. A termographic camera detects radiation in the infrared range of the electromagnetic spectrum and produces two-dimensional (2D) images of that radiation.
Any object, including solar panels, emits infrared radiation based on its temperature. This equipment makes it possible to "see" an object or living person, without any visible illumination.
When is the IR imaging test used during PV production?
Many PV manufacturers find the infrared imaging test useful as it detects a variety of problems. The most logical moment to perform this test is before the solar panel lamination.
In case of any defects found, the solar panel can still be repaired and tested for a second time, before it will be laminated.
Most PV manufacturers, and especially third party quality testing bodies, also perform the infrared imaging test after lamination. From our experience we know that panels often get damaged during the lamination process.
The cause is often inaccurate connections between the cells (ribbon connections), that will crack the cells once pressure is performed through laminating.
Of course once the solar panel is laminated, the manufacturer has no chance to repair the panel. The best it can do is sell it as B-grade.
Which defects can be found with infrared imaging on solar panels?
There's a variety of defects that can be spotted with this test. The main defect that inspection companies find are badly soldered connections. This is the cause of the majority of problems.
For instance: a cell that is connected with two tab ribbons. In case one ribbon is not soldered properly, the other ribbon will take over its function, but will generate a higher current which leads to increased temperatures.
Then, it is possible to find inactive cells or short-circuits in cells. If this isn't caused by badly soldered connection, then these defects could probably have been removed during the cell test, at the beginning of the manufacturing process.
Are there any other applications for infrared imaging in the solar industry?
Infrared imaging is useful for a many different applications. One common issue when installing solar panels on a roof, is the state or quality of the roof itself.
Basically a roof needs to be in such good state that it will last for the lifetime of the solar panel installation. If not, the solar panels will have to be removed from the roof, which will bring extra costs.
Professional installation companies use the infrared technology to determine if a roof has no leakage. This so called infrared roof moisture survey has become common practice when evaluating the roof before installation.