The term “Tier 1” refers to the “bankability” of the solar panel manufacturer, not the quality of the solar panel itself.
The Tier 1 ranking scale was created by Bloomberg Energy Finance Corporation as a way to rank solar panel manufacturers in terms of their financial stability.
Bloomberg defines a Tier 1 solar manufacturer as “those which have provided products to five different projects which have been financed non-recourses by five different banks in the past two years”.
Tier 1 solar panels only come from the top 2% of solar manufacturers that are vertically integrated which means every stage of the manufacturing process is quality controlled. The manufacturer also uses advanced robotic processes and invests heavily in research & development. They must also have been manufacturing solar panels for over 5 years to qualify.