PV projects are a relatively new type of investment, whose technology has not been tested for a long time, mainly with regard to interconnected systems and PV parks. In addition, they operate outdoors, where they are subject to all environmental changes. A power drop in a PV project can come from many causes, so it requires monitoring as well as regular and thorough maintenance according to the standards, if possible, any cause of damage could be preventable in the bud and not take on dimensions. One of the most widespread international problems that generates power drop in PV systems and parks is the Potential Induced Degradation known as PID*.
The PID (Potential Induced degradation) effect reduces the voltage and therefore the power of PV projects to a large extent. PID is reversible for crystalline PV and is treated with the use of voltage rehabilitation devices, the so-called Offset Boxes. As soon as the PID is diagnosed and treated, the faster the power comes back. In cases that the power loss is high, much time is usually needed to restore the power of the park. It is estimated that the power reset time of a park is almost equal to half the time of degradation.
This phenomenon is greatly favored and accelerated by the high temperature, humidity and high operating voltage of the strings (voltage of strings) **. Especially if the PV Park is located in a marine environment, the PID effect occurs in a shorter time and the degradation of producing power is more intense.
Seners Company deals with PID since October 2010, when the power of its PV Park that was located in a marine environment downgraded by 12% within six months. With the installation of Offset boxes the performance of the park has been returned. Since then and until December 2014, Seners Company has installed more than 500 Offset boxes in PV projects of its own (as EPC) and in third-party projects and with PV panels of various construction houses.
Regarding the problem of PID, we have noticed based on our experience that the sooner the phenomenon is perceived (if possible at its start) the faster the park comes back to its previous condition with no remaining problems. In general, with appropriate monitoring and proper maintenance, many problems in PV projects can be avoided or at least treated in time. Each PV system, small or large, is an investment. No investment pays off without supervision and preparation of any repairs that may be required.
* The PID effect is purely a physico-chemical phenomenon of the PV element itself (cell), which affects its tendency and therefore its strength. It is about transferring unwanted ions to the contact of the PV module (P-n junction), resulting in the destruction of electrons and holes produced in the diode (junction), thereby reducing the tendency of the element (cell). The scientific understanding of this phenomenon requires a very good knowledge of semiconductor technology.
* * In Greece we have high temperatures, enough humidity, and many and large areas within marine environment. Also, the tendency of strings (strings) in interconnected systems and parks is quite high, usually over 600V. These conditions are in favor of the development of the PID effect and many projects in the Greek area over time will display this effect, regardless of the construction house.