An important leverage in reducing the cost of photovoltaic energy generation is increasing the power output of the individual solar modules in an installation. Optimizing the efficiency of the individual cells assembled into the modules is often the main focus. However, additional large optimization potential is present at the module level. In this study, we investigate the influence of different design parameters such as cell spacing and solder ribbon type on the encapsulation losses of a solar module using single-cell modules, as well as large 60-cell modules. Combined with a model for series resistance losses encountered during encapsulation, this allows for the prediction of the power output of different module designs and, thus, for simultaneous optimization of different design parameters. The findings were directly introduced in the design of the latest generation of Q-Cells solar modules. These optimized modules were installed on Q-Cells' test field in order to generate yield data. The data show that the optimized design increases not only the modules' performance under standard test conditions but translates into an equivalent gain in energy yield in the field as well.