Micro-cracks, also called micro-fractures, are microscopic cracks that have developed in photovoltaic cells, hence the shortened term micro-crack. Although poor shipping, packaging, and installation can result in microcracks, micro-cracks are most commonly caused by thermocycling.
Thermocycling is a process in which the silicon in solar cells expands during the day due to warm weather, and contracts during the night when it is cooler. This frequent movement wears the silicon and can cause it to crack.
As time goes on, micro-cracks grow larger, eventually degrading the panel’s cells. Note that not all micro-cracks are detrimental to a panel’s lifespan or energy production, but nonetheless it’s still a good idea to be aware of their causes and effects if complications occur. Larger micro-cracks may often result in high PV cell resistance, leading to a reduction in solar panel efficiency and lower power output.
To lower your risk of acquiring panels with micro-cracks, be sure to buy from a reputable manufacturer. In most cases, electroluminescence (EL) or electroluminescence crack detection (ELCD) testing is a standard practice used by manufacturers both before and after panel lamination to ensure the quality of the product.
However, some manufacturers may skip this step due to budget cuts, low resource availability, and other factors. For this, as well as other aspects of product quality, tier 1 solar panels are highly recommended in the solar industry.
When ordering panels, it’s highly recommended to buy in bulk, even if it’s just a set of five or ten modules. Singular panels often get damaged more easily during the shipping process, while larger sets of panels tend to be more secure in shipping containers.
As mentioned earlier, the installation process can also be a factor that leads to the development of micro-cracks, especially if a homeowner installs their panels themselves. To reduce mechanical stress, avoid stepping and leaning on panels, resting equipment on panels, bumping panels on the roof, and hitting solar panels together throughout the installation process.
Most importantly, buy a panel that can thrive in the environment in which you are located. Research the designated area in which the solar panels will be assembled while checking which type of solar panel satisfies those environmental needs. Create an environmental factor checklist for your area or use the one below.
Environmental Factor Checklist:
Maximum snow pressure
Maximum wind pressure
Average hail speed and size
To identify micro-cracks, homeowners may also utilize electroluminescence (EL) testing. However, this process often requires a professional, an abundance of time, and a significant amount of money, depending on the number of solar panels that need to be tested.
EL testing requires a special camera to take images almost in the infrared part of the light spectrum. This allows for a better examination of the crystalline silicon used in solar cells, making cracks visible under this particular lighting.
As a result, EL testing allows for owners to spot the exact location of micro-cracks on their panels. This information can give owners some insight into how the panel was damaged, and help owners to prevent this damage in the future.
Although EL testing is highly effective at revealing the location of micro-cracks, this form of testing does not provide much information on the effectiveness of the panel. For this reason, some homeowners will choose a different method to examine defective modules.
The most common alternative is an IV curve tracer, such as the HT I-V 400W and HT I-V 500W, which can be purchased to verify the panel’s abnormal output. Note that the included SolisCloud I-V curve tracer is available to those who have purchased a Solis inverter for their PV system.
Some tracers are even able to calculate the Voc, Pmax, and Isc of the panels. Proper analysis of these specs can help homeowners root out the malfunctioning panels that are causing the system output to decrease.
Once an issue with a particular panel has been verified, find the module’s linear output warranty. It most likely will be listed on the manufacturer's warranty document or on the bottom portion of the module’s spec sheet.
If the panel’s output is below the insured output covered by the linear performance warranty, call or email the manufacturer for a refund or replacement. Remember to include the results of the EL or I-V curve tracing tests as proof of which modules are damaged and how they are damaged.