Solar PV modules are the key components of the solar power systems that are the ideal renewable solutions for electricity. The PV modules consist of cells through which the sun rays are converted into current. When current passes through these cells, light is emitted from them. This phenomenon is referred to as electroluminescence. Testing the modules by observing their electroluminescence (EL) is a great way to detect any defects in the distribution of current or the structure of the modules.
EL testing is, therefore, used at various stages of the solar O&M to identify a number of structural issues.
The most common issues that can be identified through EL testing include the following.
Minute cracks may appear in the silicon wafers that form the solar PV cells. This can be a result of damage that occurred during the manufacturing, delivery, installation, or operation of the modules. Microcracks can cause the cell part to become inactive, having varying effects to none at all.
These cracks are more severe since they stop of flow of current passing through the area. Hot spots and thermal dissipation also occur which damages the panel due to heat. It’s imperative to identify these cracks before more damage occurs to the panel.
When the modules are being soldered, at times, the temperature may not be high enough. This leads to cold soldering which eventually causes interference in the connection between the cell ribbon and cell tab. Apart from the loss of power, the cold soldering can also turn into hot spots which become a fire risk.
Bypass diode failure means that one of three cell strings in the module gets switched off. This leads to a decrease in the output by one-third. In these cases, the biode should be replaced instantly to prevent this loss and avoid any junction box burn.
A long series of interconnected solar panels make up the solar power plant with the ability to create high voltage. Low-quality cells may not be able to keep up with the large voltage which leads to failure. This Potential Induced Degradation (PID) defects can be easily identified through EL testing.
Dead cells are no longer able to conduct current, often caused by mechanical stress as a result of a cell crack.
EL testing of solar PV cells does not have to be conducted at a defined time frame in the course of the projects. It is beneficial for different reasons at different stages of the project.
It is useful to identify any defects at the beginning, as the cells and modules are being manufactured. It reduces the rejection of batches and future warranty claims.
An inspection conducted by a third part also offers the buyer confidence in regards to the quality and the efficiency of the modules. Any required replacement is then done before it reaches the destination.
This is essential to identify any damages that occurred in the process of transportation. Bad handling of the modules will lead to cracks or micro-cracks, for which, the buyer can claim replacement and transport insurance.
Bad handling during the installation process is also likely to cause damage in the form of cracks and breakage. EL testing can identify these accidental damages and prevent future loss.
EL testing is also useful to assess the after-effects of floods, cyclones, hailstorms, and other unavoidable calamities. The results can be used to get protection against future losses caused by the calamity. This is especially important since insurance policies tend to have a certain time frame within which the damage must be reported.
Overall, EL testing can help to identify and therefore rectify a number of different types of damage at any stage of the solar PV module project.
Originally published at http://realestateandepc.wordpress.com on June 14, 2022.
