Investigation of bypass diodes for solar panels

In this paper, the properties of flat integrable bypass diodes for solar photovoltaic modules are investigated. Bypass diodes prevent a power loss of photovoltaic modules once one or more serially interconnected cells are covered with shadow. In addition, these diodes also prevent occurring problems of overheating and destructive “hot-spots” in case of high voltage solar cell strings covered with shadows. Flat bypass diodes could potentially be laminated nearby protected solar cells thus enabling more flexibility once selecting the module circuit layout or even elimination of a junction boxes on modules. The aim of this paper was to investigate temperature and voltage changes of newly designed integrable bypass diodes under the influence of direct current. During the experiment, five bypass pn junction silicon diodes integrable directly in the solar module were investigated and peculiarities of their voltage and temperature changes were revealed. Dependences of voltage on temperature matched theoretical predictions, thus confirming the quality of diodes. One of these diodes was laminated between two glass panes, thus reproducing the conditions of a real solar photovoltaic module. Measurements with this device revealed the influence of contact wire resistance changes, which has to be better taken into account in future measurements