Monitoring Variability in Distributed PV

With increasing integration of distributed solar photovoltaic (PV) resources onto the distribution network, electric utilities are increasingly being challenged to better understand PV output variability and suitable management techniques for maintaining grid reliability. This in mind, EPRI is partnered with a number of U.S. utilities to monitor distributed PV systems and provide a detailed characterization of their output variability in a variety of local environmental conditions. Detailed, high resolution (one-second) solar input and electric output data is currently being collected at nearly 60 sites clustered predominately in the Southeast and West Coast regions. (Data collection is ultimately slated to occur at 200-400 single-module locations throughout additional regions of the U.S.) Among the issues under evaluation: the effects that fluctuating voltages caused by solar ramp rates from cloud movements, shading, and temperature on PV generation output have on the grid; and PV performance comparisons in high penetration PV scenarios.

This presentation (to be delivered jointly by EPRI and a partner utility) will describe this multi-year study’s methodological approach, in-house monitoring instrumentation package, and data collection parameters. It will next provide latest monitoring results and analysis—including a “magic carpet” video depicting geospatial time-elapsed performance of multiple distributed PV systems—detailing empirical findings as well as others derived from modeling various system scales and circuit penetration levels. A concluding discussion will address perceived capacity levels that are required to add varying levels of PV to the grid system.