The proper methodology for grounding solar arrays and solar systems is dictated by the National Electric Code (NEC). As a extension of the NEC every equipment manufacturer, specially PV module makers, have their own suggestions for grounding their PV modules. Manufacturer’s suggested grounding practices must always comply with the NEC and UL article 1703.
Even though all electrical equipment in a solar photovoltaic system must be properly grounded, including inverters, racking and electrical boxes, PV modules are the main grounding safety concern for inspectors. Grounding lay-in lugs have been extensively used for grounding PV modules; now the use of grounding lay-in lugs is being substituted by grounding clips which eliminates screwing the set screw by just clipping the cable. There is also stainless steel grounding bolts for solar systems installed in corrosive environments. Another grounding practice which has gained a lot of momentum is grounding washers, commonly called WEEBs, which eliminates screwing lugs or clips to individual modules all together. By piercing the solar modules to the mounting rails the WEEBs can properly ground an entire row of solar modules with only one lug, reducing labor and copper cable consumption considerably.