Effect of Module Orientation and Batteries on Performance of Building Integrated Photovoltaic Systems

This paper explains the working principle of the free and open source software “POW” (Photovoltaic Optimization Ware), the tool works on the increase of self consumption of the load and on the balance of capacities between the components. The main innovation is providing the capacity of the BIPV system as an output instead of an input, this feature can better integrate the BIPV system in the building design process. The output of the tool is in fact the suggested capacity for each surface of the building (roof + facades) that should be installed to maximize the NPV (Net Present Value) of the system. Some results produced using the tool show that the annual cumulative irradiation cannot be the only parameter considered when installing a PV system in a building. It is shown that it can make sense to install part of the capacity in the least irradiated slope of a roof, thus to better fit the production curve to the demand curve and so increase self-consumption. Another example shows how part of a system can be placed on the façade instead of the roof in the presence of electric heat pump as an heating system. This phenomenon persists also when combined with a prominent electric storage system. In general the orientation of the modules in terms of Azimuth loses importance when batteries are installed, but the orientation of the PV module in terms of tilt keeps holding primary importance, because it influences the seasonal production profile of the system.