Low feed-in tariffs for power generated by photovoltaics in Germany cause increasing efforts to raise the amount of self-consumed energy. Battery systems can be used to temporally decouple energy production from consumption in order to achieve a higher percentage of on-site consumption. To decide whether this investment is economically viable for a specific household, the interaction between PV plant, battery and consumer is simulated. Load profiles of the simulated household are important input data for these calculations and are obtained by smart metering. In the ideal case, profiles are recorded for a whole year in subsecond resolution, but for real-world applications, this is usually not feasible. This paper attempts to quantify the effect of both short recording eriods and low time resolution on simulated on-site consumption.