Experimental Investigation of Hotspot Detection and Isolation in Shaded Photovoltaic Cells

In recent days utility of renewable energy sources is increased for various purposes and at varied locations under various conditions. While using solar panels for generation of power, many challenges are there. One of important challenge is partial shading of the panel and subsequent failure of PV cells due to hotspots. In the shading on the PV cell, the shaded part of the module operates at current levels higher than those of the non shaded PV cells, and affected cells are forced to reverse bias and start to dissipate power, consequently temperature increases due to overheating (hotspot) of the PV cells. Hotspot may also occur due to some manufacturing defects, impurities of the PV cell material etc. Based on these considerations an automatic detection scheme (KIT) is developed to identify the hotspot condition, and to isolate the PV panel which is under hotspot hence avoid the permanent damage of the cell and remove the power losses. If an error is detected (the current is reversed), the micro controller gives the signal to alarm circuit and relay circuit. Then the Alarm circuit gives an alarm sound and the affected panel is isolated by using relay circuit and restarts automatically if the error is removed. The removing of error is done by manual removing or panel tracking or automatic cleaning systems (depending on requirement).