Reductions in the cost of PV and batteries have the potential to encourage households to invest in PV-battery prosumage. This may have wide ranging implications for the rest of the electricity system. We explore these system impacts, using two open-source techno-economic models and apply them to scenarios in Western Australia for the year 2030.

Household PV capacity generally substitutes utility PV, and less so as additional household batteries are installed. Wind power is less affected, especially in scenarios with higher shares of renewables. With household batteries operating to maximise self-consumption, utility battery capacities are hardly substituted. Wholesale prices faced by non-prosumage households slightly decreases with prosumage, while those of other consumers are slightly increased.

Overall, the growth of prosumage has substantial implications on optimal utility investments and dispatch and should thus be considered by all electricity system participants.