This dataset contains current–voltage curve measurements of several photovoltaic modules used in the OptimalPV project funded by the Research Council of Finland (funding decision 348701). The measurements were performed at the Tampere University Photovoltaic Power Research Plant located in Tampere, Finland and at the University of Malaga, Spain. If you use the data provided, please cite the following items: Regarding the data: this Zenodo dataset (K. Lappalainen, H. Kalliojärvi, M. Talvi and M. Piliougine. (2026). Photovoltaic module current–voltage curve data from OptimalPV project. Zenodo. https://doi.org/10.5281/zenodo.20472706.) Regarding the measurement system of Tampere University: D. Torres Lobera, A. Mäki, J. Huusari, K. Lappalainen, T. Suntio and S. Valkealahti. Operation of TUT solar PV power station research plant under partial shading caused by snow and buildings. International Journal of Photoenergy 2013, 837310. https://doi.org/10.1155/2013/837310. Regarding the measurement system of the University of Malaga: M. Piliougine, J. Carretero, L. Mora-Lopez and M. Sidrach-de Cardona. Experimental system for current–voltage curve measurement of photovoltaic modules under outdoor conditions. Progress in Photovoltaics: Research and Applications 19 (2011) 591–602. https://doi.org/10.1002/pip.1073.