Building Integrated Photovoltaic Systems: specific non-idealities from solar cell to grid

After an initial phase of great diffusion of large Photovoltaic (PV) systems installed on the ground, the recent evolution of the feed-in tariffs makes the Building Integrated PV (BIPV) systems for residential, commercial and industrial users, the more befitting application of the PV technology. Unfortunately, the building integration implies some critical issues on the operation of principal components, such as the PV panels or the grid-connected inverter, typical of this kind of installation and not so important in the case of ground mounted PV plants. These non-idealities can be due to: presence of obstacles near the PV panels, like trees, poles, antennas, architectural elements (chimneys, barriers, buildings in the neighbourhood); non-optimal orientation of the PV field (not Southward) or with different orientations among the sub-fields, with consequent production asymmetry between morning and evening or mismatch; sub-optimal tilt angle of the PV modules, as it is fixed by the building roof; not-efficient cooling of the PV panels, which can cause temperature gradients both horizontally, between PV modules in the central area of the field and the peripheral ones, and vertically, between panels installed in the bottom and in the top of a structure, due to the direction of the cooler flow. The consequences of these non-idealities is the subject of this PhD dissertation, from both theoretical, through convenient simulation tools, and experimental viewpoints. The most evident of these effects is the mismatch of the currentvoltage characteristics of the PV field panels. With the aim of illustrating the analysis methodologies used to study the mismatch effect on all the PV system components, a specific case study is considered, constituted by a large BIPV system (almost 1MWp) installed on the roof of a wholesale warehouse.