Sayın, SelçukYetgin, Fatma2025-08-102025-08-1020252667-8055https://doi.org/10.36306/konjes.1581774https://search.trdizin.gov.tr/en/yayin/detay/1318424/a-comparison-of-actual-and-simulated-data-to-determine-the-effect-of-loss-parameters-on-the-performance-of-building-integrated-photovoltaic-systemsThe efficiency of photovoltaic systems is not very high, but the initial investment costs are high. Simulation programmes are used to determine the efficiency of the photovoltaic system to be installed and to calculate the energy production values. However, there are differences between the simulation data of the photovoltaic system and the actual production data. The aim of this study is to compare the actual production data and simulation data of a photovoltaic system in use. For this comparison, a factory building in Beyşehir, Konya, which has a photovoltaic system integrated on its roof, is analysed. PVsyst 7.2.14 tool was used for the simulation of the photovoltaic system. The simulation data obtained from the PVsyst tool of the photovoltaic system were compared with the actual production data of 2021. While the actual production data of the system in 2021 is 1372,2 Mwh, the production data obtained from the simulation is 1345,1 Mwh. In order to determine the reason for this difference, the effect of dusting loss, temperature loss, module mismatch loss and aging loss parameters on energy production was analysed through different variations.eninfo:eu-repo/semantics/openAccessSolar EnergySimulationBuilding Integrated Photovoltaic SystemsLoss ParametersArticle10.36306/konjes.1581774