The Impact of Residential Batteries on PV Self-Consumption and PV Exports: early results from the Nextgen Trial in the ACT, Australia

Due to a growing number of residential photovoltaic (PV) installations, an increasing amount of energy is being exported to the grid during times of maximum solar irradiance, potentially causing technical issues such as voltage variation and reverse power flow. Energy storage is one solution to reduce PV exports. Here, we assess the degree to which the Next Generation (Nextgen) Energy Storage program, based in the Australian Capital Territory (ACT), Australia, has increased PV self-consumption and thereby reduced PV exports to the grid. The Nextgen program is one of the largest roll-outs of household batteries world-wide. Beginning in 2016, it will eventually involve up to 5000 households and businesses. Energy data collected as part of this trial provide an unprecedented opportunity to understand both the economics of battery storage as well as the technical impact of household batteries on the grid. Here we show that, for customers surveyed to date, residential battery storage increases PV self-consumption from 34% to 58%. Residential battery storage was more effective at reducing import peak power compared to export peak power. Average import peak power decreased by 39% in summer and 30% in winter. In comparison, average export peak power decreased by 16% in summer and 23% in winter. Choice of battery operation algorithm will be important for reducing this export peak power further.