An Embedded System for the integration of a Combined Photovoltaic Solar (CPS) system into a ZigBee Home Area Network

In this paper is reported the design and implementation of an electronic system capable of communicating over a standard ZigBee network in order to let a residential gateway collector, named agent, gain access to the parameters of a Combined Photovoltaic and Solar thermal (CPS) plant, thus realizing a networked energy production appliance . The system is made of three parts: a PV metering device, a boiler metering device also capable of controlling a heating resistor embedded within the boiler tank, and a data collector acting as a ZigBee node. The data collector device periodically retrieves the following parameters from the metering devices: instantaneous photovoltaic power production, accumulated photovoltaic energy, instantaneous boiler heater power consumption, accumulated energy consumed by the boiler resistor, water temperatures in three distinct points of the boiler. Since solar thermal and photovoltaic panels are located out of the ZigBee communication range, an RS485 wired link between the three devices has been implemented, while the collector, usually located not far from the agent, has wireless visibility. Some of the parameters listed above are already monitored by proprietary CPS digital systems. However the implemented ZigBee nodes make these parameters accessible through an open and interoperable standard. Various IC manufacturers including Texas Instruments and Freescale provide ZigBee enabled solution. The development of the system is based on the Texas Instruments solution is described and their advantage and limitations have been experimentally studied in order to explore the possible application area.