This paper aims to revisit the way that distributed energy resources (DERs) interact with the present structures of the Australian National Electricity Market (NEM), and consider opportunities to improve the interface between centralized and distributed resource operation and investment. The NEM was established with the stated aim of facilitating efficient operation of and investment in electricity systems across the Eastern Australian States through more competitive, market oriented arrangements. It was, however, designed at a time when DERs did not have a significant impact on the electricity system.
Distributed photovoltaic (PV) and battery storage systems, among other DER technologies such as ‘smart’ building management systems and appliances, may represent welcome new sources of competition in wholesale and retail markets, yet it is unclear whether present NEM arrangements provide a coherent or comprehensive interface between utility scale and decentralized end-user decision making. For example, utility scale PV systems reside within a wholesale market that requires them to participate in scheduling and provides dynamic pricing of both energy and ancillary services. By contrast, residential PV systems sit within retail market arrangements that utilize net metering of household demand and generation, and provide effectively fixed volumetric tariffs. The two markets do interact, of course - household PV systems can in aggregate influence wholesale prices by reducing the overall supply of energy provided by that market. And wholesale prices do eventually impact on residential tariffs that drive the case for residential PV uptake. However, this interaction would seem to lack coherence and comprehensiveness.
These factors already appear to be impacting market and customer outcomes at the current deployment of approximately 5GW of rooftop PV. Some forecasts predict that the system will need to support up to 19 GW in the coming two decades. This raises important questions around whether incentives from the NEM’s wholesale and retail structures are facilitating efficient investment and operation in this space and, if not, what might be done.
In this paper, existing NEM wholesale and retail market arrangements are examined in the context of growing DER penetrations, to provide a preliminary assessment of whether they provide a suitable framework for coordinating efficient operational dispatch and investment across both utility scale and distributed energy options, and energy consumer decision making more generally. A number of key challenges are identified in present arrangements, and possible opportunities to improve key aspects of them are presented.