The panels are new from the manufacturer. Grade B panel has the same output as grade A panel. It has some cosmetic defects. There may be cells not aligned, tapping wire across the cell, dirt on the glass,.... Some of them look perfect. All the solar panels were tested and working well. There is no spec sticker at the back of the panel and no warranty for grade B solar panel.
It is good for off grid installation, not suitable for grid tied installation. We sold thousands in the last few years and have no issues with it.