NOVELTY - The system has monitoring modules (300) associated with power sources and collecting performance data of the source. A set of transmitters is associated with one of the monitoring modules and transmits the performance data. A set of microcontrollers (102) is associated with one of the transmitters, and controls transmission events according to elapsed time from timer initialization. The source is connected to a power line. The transmitter transmits the performance data over the power line. The monitoring module comprises a current measurement module (301) for collecting current data.    USE - Central monitoring system for installing a distributed direct-current (DC) power source e.g. solar panel (claimed), photovoltaic solar cell array, fuel cell and battery for hybrid cars, in a residential application and a large solar panel field power plant.    ADVANTAGE - The microcontroller can perform monitoring, logging and communication functions to allow for quick and easy troubleshooting during installation, thus significantly reducing installation time. The microcontroller performs functions to provide quick detection of problems during maintenance work. The system performs preventive maintenance in a timely manner to avoid downtime of the system by monitoring operation of a part of the system. The system calculates power production from a string to avoid power drops and malfunctions at the string, thus providing improved identification of failing or malfunctioning panels without expense of installing monitor at the panel. The system allows analysis of sensor information to detect power losses caused by environmental conditions, thus preventing costly and difficult solar array testing. The system allows transmission to be done as power line communication in a one-way implementation, so that collisions can be avoided or minimized by using a unique transmission timing mechanism.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for monitoring distributed power harvesting systems.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of a monitoring module.    Microcontroller (102)    Monitoring modules (300)    Current measurement module (301)    Communication module (303)    RAM (305)