a rotor blade for use in a wind energy system is provided with the rotor blade having a rotor blade body comprising a rotor blade body tip ; a rotor blade body cavity ; and a lightning protection unit . the lightning protection unit includes a conductive part that is connected to a down conductor and positioned within the rotor blade body cavity close or at the rotor blade body tip , the conductive part having an extension protruding out of the rotor blade body for receiving a receptor . according to another aspect of the invention , a wind energy system is provided with at least one of such a rotor blade . further , a method for constructing a rotor blade for use in a wind energy system is provided with the steps of manufacturing a pressure side shell and a suction side shell of the rotor blade ; applying a conductive part to an inner side of the pressure side shell or the suction side shell with the conductive part including a body and an extension ; and forming the rotor blade by joining the pressure side shell and the suction side shell together in such a way that the body of the conductive part is in the rotor blade and the extension of the conductive part protrudes out of the rotor blade .