Scrap solar wafers are primarily categorized by their material type and physical condition. You must distinguish between Monocrystalline (Mono) and Polycrystalline (Poly) scraps, as Mono typically commands a higher price due to its higher purity and efficiency in recycling. Quality is further graded into 'Broken Cells' (with busbars), 'Blue Wafers' (nitride coated), and 'Bare Wafers' (virgin silicon scraps). Ensure the resistivity levels and P/N type (typically P-type) meet your recycling or manufacturing requirements, as these factors significantly impact the valuation.