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 pa. Like elementary school, solar panels are graded on several factors, mainly visual and performance f. 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 t. 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.