Rotor blade with a lightning protection unit, wind energy system having the same and a method for constructing a rotor blade

A rotor blade for use in a wind energy system is disclosed. The rotor blade includes a rotor blade body comprising a tip; a down conductor extending along the rotor blade body; a conductive part including a conductive part body attached to the rotor blade body and connected to the down conductor, and an extension extending outward from the conductive part body and protruding out of the tip; a lightning receptor having a cavity for slidably receiving the extension; and a fastener removably fastening the lightning receptor to the extension.