Abstract: Methods for measuring insulation resistance in a photovoltaic (PV) array may include partitioning the PV array into groups of PV panels, isolating a group of PV panels selected for an insulation resistance measurement from other groups of panels by setting bypass selectors on each PV panel in the PV array, and making an insulation resistance measurement for the selected group. If a measured value of insulation resistance for a selected group corresponds to an insulation problem in a PV array component, a separate measurement of insulation resistance may be made for each PV panel in the selected group. Insulation resistance measurements may be made accurately and rapidly for large PV arrays without disconnecting and reconnecting cables between panels. Measurements may be made at frequent, regular intervals to permit changes in insulation resistance to be detected before damage from dielectric breakdown occurs.

Abstract: Embodiments of a network topology for monitoring and controlling an array of solar panels include an intelligent node adapted to send and receive data and commands by at least two redundant means of communication. An intelligent node includes a solar panel, a node controller, a photovoltaic module, a bypass relay, a bypass bus, PLC and wireless communication interfaces for redundant means of communication, and sensor and actuator interfaces for monitoring and controlling the intelligent node. A PV module in the intelligent node may selectively be bypassed without interrupting network communications. Some embodiments include a plurality of intelligent nodes electrically connected serially into a chain of nodes and further connected to a gateway. Other embodiments include a plurality of chains of nodes connected to an inverter and a transformer, thereby defining an area. Additional embodiments further include a central server in communication with a plurality of areas.