Arc fault detectors in photovoltaic inverters have been known for a long time, but they have only become common in the European market since the early 2020s. In a measurement project, the arc fault detectors of three inverters were compared. The testing was conducted not only in accordance with IEC 63027:2023 but it was also examined how well the arc fault detectors perform with long string lines. The results show that all tested devices deliver good performance, even with long cables.