Very advanced standard silicon module: German module manufacturer SolarWorld offers glass-glass panels with bifacial cells and 5 busbars, based on monocrystalline PERC technology. The photo shows the module from the front and back.
Monocrystalline solar cells are made out of silicon ingots, which are cylindrical in shape. To optimize performance and lower costs of a single monocrystalline solar cell, four sides are cut out of the cylindrical ingots to make silicon wafers, which is what gives monocrystalline solar panels their characteristic look.
A good way to separate mono- and polycrystalline solar panels is that polycrystalline solar cells look perfectly rectangular with no rounded edges.