Since reaching 20% efficiency, research in perovskite photovoltaics has shifted from a race for efficiency to a race for stability. For efficiency, the standard test conditions set the rules for the race. However, the term 'stability' is used very broadly and assessed in various ways, meaning different groups are running different races. For the application, only energy yields that can be achieved under real-world, long-term operation matter. Here, we characterize and analyse the performance of an efficient perovskite solar cell (PSC) under simulated ambient conditions based on real temperature and irradiance data from selected days over one year at a location in central Europe. We find that the PSC shows only a low decrease of efficiency with elevated temperature and low light intensity, maintaining almost optimum values for ambient conditions, under which most of the solar energy is incident on the solar cell. The overall energy yield differs from what is expected from standard test condition measurements and is influenced by reversible degradation (delivering the highest performance in the morning) and by a slight permanent degradation that is observable during the year. With reference to tandem cells, we compare the PSC with a silicon device.