Curtailment of distributed photovoltaic (PV) and battery energy storage systems will have significant implications for power system transition around the world. Australia offers a unique case study as it has highest installation rate of distributed-PV and growing fleet of battery energy storage systems. Distributed-PV and battery inverters in Australia are required to exhibit voltage-responsive power-quality response modes to prevent excessive voltage rise caused by increasing day-time energy exports, but these modes can curtail power output and limit the value that can be gained from the renewable energy assets. For the first time in Australia, this paper studies all three inverter power-quality response modes and develops novel algorithms to assess curtailment. The algorithms are applied to a real-world dataset of 1-sec distributed-PV and battery power measurements from 1300 residential households; therefore, data resolution is higher and sample size is larger than previous related studies. Using these datasets, the study compares the experienced curtailment between distributed-PV only sites and distributed-PV coupled with battery sites for the first time. The study investigates and quantifies the energy loss due to curtailment within the South Australia region with over 40% distributed-PV penetration which has the highest uptake in the world. The results show that average curtailment loss was 1.5% for distributed-PV only sites and 0.2% for distributed-PV coupled with battery sites, however, some sites were heavily impacted losing up to 25% of generation. The reasons for the larger curtailment loss were identified as wiring and network connection faults and high voltage set-points at households' respective local substations. Other potential reason for the heavily impacted sites is being located towards the end of the low voltage feeder, however this couldn't be verified due to lack of spatial data. The large variation in curtailed generation across sites raises concerns for system owners and suggests further inquiry into the power-quality response mode design and regulations. The study also examines inverter conformance using real-world operational data for all three power quality response modes for the first time, and the results showed a low rate of conformance according to the Australian Standards and there were various discrepancies in the execution of these modes which raises concerns considering the increasing importance of distributed-PV and battery inverter fleet in supporting network operations and security. The results therefore warrant further investigation into the reasons behind these discrepancies and devising appropriate mechanisms to tighten inverter conformance checks.

Australia has world leading uptake of distributed PV (D-PV) and increasing installations of battery energy storage systems (BESS). D-PV and BESS can provide various economic and environmental benefits to energy users, network companies and other industry stakeholders. However, integrating increasing levels of D-PV into electricity networks present a range of social, technical, and regulatory challenges such as voltage management in low voltage networks. To help distribution network service providers in managing network voltage effectively, it is increasingly required that inverter-based D-PV and BESS implement one or more of the following power quality response modes (PQRM): tripping (anti-islanding and limits for sustained operation), Volt-VAr (V-VAr) and Volt-Watt (V-Watt). The PQRMs can curtail power output which may limit opportunities and revenue that D-PV and BESS owners obtain from their investments. On the other hand, these modes can help with the management of voltage. Curtailment and Network Voltage Analysis Scoping Study (CANVAS) is a RACE for 2030 scoping study by the Collaboration on Energy and Environmental Markets at UNSW, including industry partners AGL, SA Power Networks and Solar Analytics. The study analysed two datasets including 1000 BESS sites from AGL's Virtual Power Plant trial and 500 D-PV sites from Solar Analytics' customer database both within the metropolitan Adelaide, focusing on the first two PQRM modes: tripping (anti-islanding and limits for sustained operations) and V-VAr curtailment. The study found a range of V-VAr response behavior from BESS and D-PV likely to be due to different installation dates and legacy standard settings. The tripping and V-VAr curtailment were not significant for most energy users (less than 1% of total generation); however, some energy users lost up to 20% of their total generation. This clearly raises the issue of fairness in relation to curtailment which will become a more prevalent issue as D-PV penetration increases.

This study analyses distributed photovoltaic (D-PV) system curtailment and impacts on consumers in response to high network voltages. Novel analytical techniques are applied to a unique real-world operational dataset of over 1300 D-PV systems in South Australia to identify ‘tripping’. Data-driven methods are valuable due to the diverse range of D-PV conditions. South Australia is an insightful case study due to its D-PV rich network, where around one third of standalone housing now has a PV system. Findings suggest that overall curtailment is low, however some sites experience significant impacts of up to 46–95% curtailment per day, particularly during spring. The uneven distribution of impacts raises concerns regarding fairness, however network solutions to increase hosting capacity must be carefully balanced given the potential costs imposed on consumers without D-PV. Upscaling the estimated D-PV generation loss to all of South Australia indicates a total value of $1.2m-$4.5m per year in lost value to consumers with D-PV, considering clear sky days. Implications for policy makers and network operators are discussed in the context of strong projected D-PV uptake in Australia, and around the world. It is proposed that data-driven methods could inform future regulatory assessment processes to improve outcomes for all consumers.

It's a sunny spring DAY in South Australia. A light breeze is cooling the coastal state capital of Adelaide as approximately 260,000 distributed solar photovoltaic (D-PV) systems on residential and business rooftops generate electricity, setting a new state record for the lowest minimum electrical demand for the third time this season. All looks peaceful throughout the suburbs. D-PVs form an irregular yet persistent patchwork across one-third of the houses in the state. Most consumers are going about their day without a glance at the D-PV panels on these roofs. However, the mild temperature and bountiful sunshine lead the D-PV generation to climb, causing the voltage to creep higher and power to flow in reverse across large swathes of the distribution network. Some D-PVs are tripping off, unbeknownst to their owners and the local network operator.

As distributed photovoltaics (PV) levels increase around the world, it is becoming apparent that the aggregate behavior of many small-scale PV systems during major power system disturbances may pose a significant system security threat if unmanaged. Alternatively, appropriate coordination of these systems might greatly assist in managing such disturbances. A key issue is PV behavior under extreme voltage events. PV connection standards typically specify aspects of inverter voltage behavior. However unresolved questions remain regarding compliance, ambiguity and transition between versions of these standards. In addition, how major voltage disturbances manifest in the low voltage network is complex, and analysis of operational system data could be particularly useful for establishing the behavior of distributed PV in the field. Our study utilizes 30 s operational PV generation data from 376 sites during two major voltage disturbances in Australia. Australia has one of the highest penetrations of distributed PV worldwide, and as such provides a useful case study. Results show that an aggregate similar to 30-40% reduction in distributed PV generation occurred during these events, but individual inverter behavior varied markedly. To the authors' knowledge, this is the first time the aggregate response of distributed small-scale PV to voltage disturbances originating in the transmission system has been demonstrated. Four novel techniques for analyzing events are proposed. Results show a potential increase in system security service requirements as distributed PV penetrations grow. Our findings would seem to have major implications for development of composite load models used by power system operators and for contingency management.

Distribution network operators, regulators and policy makers worldwide continue to grapple with the challenge of increasingly distributed electricity systems with growing penetrations of distributed energy resources (DER). As one example, globally, near 40GW of distributed ‘rooftop’ PV alone installed in 2017, almost 40% of total installations. Despite its growing role, there remains a stark lack of visibility over distributed energy resources (DERs) such as rooftop solar PV and residential Battery Energy Storage Systems (BESS) in many jurisdictions, and thus, a distinctly absent evidence base to guide decision making – private, industry, regulatory and policy making. Australia has one of the highest penetrations (proportion of residential dwellings with PV installed) of distributed solar PV in the world, indeed in the state of South Australia PV penetration is 32% with periods already recorded in which 40% of total state demand is being met by distributed PV alone. South Australia therefore provides a useful case study for examining challenges associated with such PV, the trade-offs which will invariably arise between small and utilityscale resources, and between energy users now facing new distributed energy options, and policy implications.

Australia has one of the highest penetrations of distributed solar PV worldwide, comprised mostly of residential rooftop systems. This paper explores the behavior of distributed PV during voltage excursions following a major power system disturbance, and implications for managing system security. Previous research has focused on the response of inverters to frequency disturbances. However, this paper presents operational data demonstrating that a major voltage disturbance can result in widespread generation loss from distributed PV. A unique data set containing 30s PV generation and local network voltage for 214 sites in South Australia is analyzed. Aggregate PV generation losses of 42% highlight the need for integration of distributed PV voltage response characteristics into power system planning and operation. Observed curtailment is upscaled to assess the potential severity of response and a method is presented for assessing diversity in individual PV inverter response with regards to depth and duration of generation loss.

Distributed energy resources (DERs) are unlocking new opportunities, and the grid is undergoing a dramatic transformation with unprecedented change. Yet as DERs continue to grow in North America and around the world, it is apparent that the aggregate amount of them is having an impact on bulk power system (BPS) planning and operation. The effects of DERs can be attributed to the uncertainty, variability, and lack of visibility of these resources at the BPS level.

Some two million distributed PV systems have been installed on rooftops across Australia over the past decade but there is surprisingly little data available about inverter market trends and therefore their potential behaviour and impact on the grid. This paper seeks to remedy this gap with regard to inverter specifications including rated AC power, DC-AC ratio, number of phases and manufacturer. We utilise data on each PV system installation collected by the Clean Energy Regulator, and made available to the Australian PV Institute, combined with the specifications of 1597 individual inverter models. We consider changes in system design and sizing over time, and by State and distribution network service provider. Our analysis highlights that as the price of PV panels and balance of systems components has fallen, there has been a shift towards installations with a higher AC output. However, this is bounded by AC inverter limits set by distribution network businesses, and inverters rated at 5kW now command the largest market share. We also see a strong trend in DC to AC ratio; where inverters were overwhelmingly sized larger or equal to array rated capacity in 2011, whereas roughly 80% of systems installed in 2018 had a smaller rated AC output than the rated DC output of the array. These changes have implications for the operational characteristics of distributed PV and hence the challenges and opportunities they pose for grid integration.

Consumers in Australia have made substantial investment into Distributed Energy Resources (DERs) and in particular, rooftop solar PV. However, there remains limited visibility of the technical conditions experienced by these technologies in the LV network. An improved understanding of these technical conditions has the potential to support more transparent, technically and economically appropriate investment and operational decision making by both consumers and network utilities. In this study, a suitably anonymised data set of voltage measurements at 2,010 sites across Australia with distributed PV provided by Solar Analytics is analysed. Our assessment highlights that, generally, voltage conditions on the low voltage networks at sites with distributed PV are high; the great majority of measurements are greater than the nominal voltage for each network region with some potential for non-compliance. Voltage conditions were also found to vary significantly over the course of the day for different regions and seasons, in accordance with varying net demand and, presumably, network voltage control actions. Importantly, a wide range of voltages are observed during solar generation periods as well as times of lowest load, with low voltage conditions seen at peak load periods in some jurisdictions. These variations have implications for the performance of distributed PV including questions of voltage ‘headroom’ for PV generation, the challenges of managing low voltage excursions at times of peak demand, as well as for network voltage management more generally. The study highlights the benefits of improved visibility regarding power quality conditions on the low voltage network.

Local electricity sharing schemes have the potential to play an increased role in the Australian National Electricity Market as the penetration of distributed energy resources (DERs) continues to grow. These models allow participants to share energy between separately owned and operated DERs, however are largely untested. While embedded networks have generally been established for specific circumstances such as shopping centres and airports, there is growing interest in their wider application in providing a framework for local sharing of energy resources. However, the potential operational and commercial implications for key stakeholders (including consumers, network operators and retailers) are not well understood. An example of one such proposal is within the Byron Arts and Industrial Estate through which the community owned retailer, Enova, is seeking to offer a bespoke energy solution to its customers within the estate. In this paper, a new open source software model for assessing technical and commercial outcomes of local electricity sharing is presented. The model is applied to the Byron Arts and Industrial Estate case study which demonstrates the relevance of modelling to support appropriate investment and operational decision-making.