An innovative open source web tool guiding the sizing of combined PV-storage systems, with a particular focus on industrial buildings. The tool allows to automatically size PV and storage systems taking into account roof size and orientation, typical meteorological conditions of the region and consumption profiles. The automatic sizing can be performed as a function of different optimization objectives, among them the maximization of the internal rate of return of the investment, the self-consumption, the autarky and the PV production. The tool also enables the users to insert consumption data to improve the estimation of self consumption and, in case data are not available, it provides means to estimate them. The tool also allows to model fleets of electric vehicles, designing usage patterns and allowing to select the number and type of vehicles with the related charging stations. Bidirectional usage of EV batteries is also possible. Since in a web tool the user experience is crucial, the optimization algorithms are designed with a strong focus on responsivity. To reach reasonable convergence times, a number of approximations are used. We provide here a validation of these techniques and assess their performance against more complex and detailed simulations. In a second step, the Optistore tool is used to automatically size PV systems on the roofs of an industrial district located in southern Switzerland. The impact at medium voltage level of the PV penetration and the effect of the storage introduction are investigated in simulation.
