Category: Finance and Asset Management
Snail trails are discolorations that appear on some solar photovoltaic (PV) modules, sometimes in association with micro-cracking and/or penetration of moisture into the cell surface through a damaged back sheet. Their prevalence and impact on system performance and reliability over time are not well understood, representing an important area of research that is relevant for the advancement of PV technology as well as those who are a part of the solar value chain, including solar project developers, investors, manufacturers and operations and maintenance (“O&M”) teams.
Typically, crystalline silicon module manufacturers warrant an annual module power degradation rate of 0.7%, starting year two (2) after being deployed in field. Any annual power degradation exceeding what is warranted by the module manufacturer can have a significant financial impact for the customer and diminish confidence in the type of technology and manufacturer for future acceptance and deployment. This poster discusses snail-trail-like formations on modules typically within their first two years of operation. This poster investigates the suspected root causes, potential corrective actions and test protocol to quantify and mitigate module defects leading to unwarranted degradation related to snail trails observed at utility scale solar PV projects primarily in the Southwest United States. For the test protocol, we discuss appropriate sample sizes, types of accelerated testing and look into durations for each of the tests for evaluation. We also contemplate various in-field testing on installed modules under load such as front and back visual inspections, thermal imaging, and I-V curve measurements to determine any initial power degradation due to snail-trail-like formations. We expect that the information presented in this poster will help the key stakeholders in the solar value chain understand degradation impacts from snail-trail-like formations further and better prepare by making considerations in their project specific O&M plans and contracts.
Saurabh Chatterjee– Senior Solar Consultant, Leidos Engineering