The grading system goes A for the best, B for visually defective panels but meet performance benchmarks, C for visually and performatively defective solar panels, and D for broken solar panels. Solar panels are graded into categories A, B, C, and D based on their quality, and the cost differences between these grades can be significant. Grade A panels, for instance, are the highest quality, while Grade D panels are typically considered low-grade materials with limited usability. Let's break them down: These are. Solar Panels Grades A, B, and C (Explained) - Solar Panel Installation, Mounting, Settings, and Repair. The expensive monocrystalline panels vs. So what kind of solar panel is called A grade, and what kind of solar panel is called D grade? Here is a brief. A key component of this progress is solar panels, which come in various grades and qualities: A-Grade, B-Grade, and C-Grade. At Sova Solar, we're often asked: “Why not just go with a cheaper panel if it's still 300W?” The answer lies in what you're really paying for — and how Grade.