The rapid rise of power conversion efficiency of metal-halide perovskite solar cells beyond 20 % has drawn huge attention. Recent certified efficiencies, however, have been marked as “unstabilized” as perovskite solar cells tend to show a hysteretic behaviour during current density-voltage (J-V) measurements. This leads to deviating results for varying scan parameters and conditions, which challenges reliable and comparable results. In particular, the extent of this behaviour is highly dependent on device preparation method, architecture, device history, and more importantly on measurement preconditions and scan rate. Thus, the demand for reliable stabilized values arises which are reproducible and comparable among different laboratories. Here we introduce an adaptive tracking of the maximum power point and the open circuit voltage. We compare these values with device characteristics derived from standard J-V measurements. Furthermore, we discuss the challenges of a correct efficiency determination and provide the algorithms for easy implementation in existing measurement systems.