Influence of the shadows in photovoltaic systems with different configurations of bypass diodes

摘要

The IU characteristic curve of a photovoltaic module is affected by shadows, depending on the shaded area of the PV module, and the radiation received by the shaded areas. Another factor in the shape of the I-V curve of a PV module, is the configuration of the electrical connection between its cells and bypass diodes. Bypass diodes are installed in the modules to prevent power consumption when they are shaded or damaged; they also prevent cells from working near the avalanche zone. This paper examines the performance of a photovoltaic array. A PV array consists of modules connected between them. Particularly, the configuration with bypass diodes overlapped is analysed, showing that totally or partially shaded modules can consume some of the power generated by other modules of the PV array. This effect is also present in low power PV arrays. In these cases, the power dissipated by a diode is small; but if there are many diodes, the power dissipated by all the diodes can be comparable with the power produced by various PV modules. Additionally, this article deals with the influence of the inverter in the MPP tracking.