The number of PV systems embedded within the GB electricity network has grown to over 800000 over the last 10 years with a combined generation capacity of over 12 GW. This growth is reducing the carbon intensity of GB electricity but poses additional problems for the system operator since embedded generation can only be monitored using statistical sampling of the generation and uncertainty in this monitoring can lead to greater levels of backup generation being needed. This project seeks to understand and quanitify errrors and uncertainty in approaches to monitor the embedded PV generation on the GB network. The project is part of wider GB PV monitoring research and collaborates with National grid and other energy stakeholders where appropriate.