A triboelectric energy generator (1) comprises a first generating element (8) and a second generating element (10). The first generating element comprises a first triboelectric material (9) and the second generating element comprises a second triboelectric material (13). Movement of the second generation element relative to the first generation element results in an output voltage, as a consequence of the triboelectric effect. A stopper (7) is configured to restrict rotation of the second generating element, so that the second generating element may only rotate through a desired angle.