Development of a module integrated photovoltaic monitoring system

The module integrated photovoltaic (PV) monitoring system is designed for measuring the V/I characteristic of each module in a conventional string over its life-time. The main aim of this paper is to propose a concept of a module monitoring system, which provides measurement data of module characteristics and is also cost efficient. Compared to currently available monitoring systems, which are able to acquire the V/I characteristic no additional wiring is needed. The system is able to connect or disconnect each module, to change the string configuration arbitrarily. The system is based on one master unit (string box) and slave units (module box), which are needed for each PV module. In order to enable data exchange between string box and module box (e.g. select module under test) a power line communication (PLC) is integrated in both units. A first prototype of the string box and the module box was developed and also tested. A user interface has been implemented in LabView to control the system and visualize the data from the string box. The results show that the developed monitoring system fulfills the required measuring accuracy and is able to measure individual module characteristics. This will also help PV cell developers to easily access information on their modules in the string and clarify the very important question of the pace of module aging.