Grade B solar panels have some visual defects that do not affect performance. Grade B naturally falls below grade A in this grading system. So how does Grade B stack up against the other grades? Grade A solar panels are entirely free of defects. Grade B has some visual flaws but still meets. Like elementary school, solar panels are graded on several factors, mainly visual and performance flaws. While this grading system follows similar logic, different manufacturers and distributors can have other criteria for their grading systems. Before buying any. So, which type of solar panel suits your needs best? The performance and pleasant appearance of grade A solar panels? The ugly appearance, yet the excellent performance of the grade B solar panels? Or can you get a group of grade C solar panels entirely. At the heart of the grading system are defects. These defects in solar panels are the basis for how they are graded, and knowing them can help you determine your grading stem for.