Hail durability on large-format modules emerges as key risk factor in site performance ratios

Cherif: “As many have taken notice, we have seen a push towards the larger format modules with full adoption of bifaciality. Bifacial technology is no longer considered a novel technology by developers and the rest of the downstream community. The larger modules with higher power outputs have become the trend in 2020, and we don’t see it slowing down. 

We have had numerous discussions with module manufacturers as well as raw material suppliers, and it seems the entire value chain is shifting their capacity towards large format modules. 
There are clear cost benefits for the manufacturers as well as a positive impact on total project cost; as module power increases, fewer modules need to be installed for a fixed target capacity.”

Cherif: “We have seen more failures in recent reliability tests where previous generations of modules had consistently performed better. Larger and more powerful modules are great for our industry; however, as modules get larger, they get heavier and more difficult to handle and install, thus potentially increasing the installation labour cost. This has led most manufacturers to reduce glass and frame thickness, both to reduce cost, and to make the modules easier to handle. This has created a challenge for these modules in their ability to withstand stringent mechanical tests. Moreover, when the front glass thickness is reduced, they are less able to withstand hail impact. This is not a great development considering the number of installations in hail prone areas as well as the documented increase in frequency and severity of hail events.”

Cherif: “High power modules in conjunction with a structurally robust module are ideal for today’s market needs. We have seen manufacturers utilize varying designs to make modules more robust. Some examples include internal support designs, thick frames and glass, etc. However, we have seen the most innovation to real life situations from tracker and racking companies who have had to adapt to this changing landscape of module sizes. New features such as hail and wind stow are very relevant to today’s PV projects and where they are being installed.”

Cherif: “Back in 2009 and 2010, we worked with the industry to introduce the first consolidated durability test protocols as a result of the countless failures we were seeing as we worked with manufacturers racing to certify modules they wanted to introduce into the market. In recent years, after we launched the bifacial characterization program in 2018 in collaboration with Black and Veatch and the hard work of Dr. Ralph Romero, we started noticing mechanical failures at a higher frequency than monofacial modules. As the modules lost some of their structural integrity, racking and tracker manufacturers compensated with different clamps and rails to maintain compliance and prevent modules from failing. However, when it came to hail, there was no other way to compensate. Glass cannot be covered or protected. 

As a result of the types of failures we were seeing, we developed a program, the Hail Durability Test, which can be used to assess the hail tolerance of modules. The results can be by developers, independent engineers, financial institutions as well as module manufacturers to assess the risk associated with installing certain modules in specific hail prone regions based on historical and projected hail severity.”