156 Multi Solar Celll A-Grade 156 multi solar cell : efficiency 14.60% ~ 16.79% ( 3.55 ~ 4.08Watt ) B-Grade 156 multi solar cell : efficiency 14.60% ~ 16.79% (3.55 ~ 4.08 Watt ) , Surface Defect C-Grade 156 multi solar cell : efficiency 14.00% ~ 14.59% (3.41 ~ 3.54 Watt ) D-Grade 156 multi solar cell : IREV2 or Big Surface Defect