knowledge about how to program and set up these systems, or they may misconfigure the systems for their intended purpose. Utilities can make their AMI data available to customers or provide some feedback to help customers maximize the value of DERs. For advanced tariffs and DER programs, AMI also enables utilities to check compliance and calculated remuneration. The aggregation of meter data by utility DER programs and tariffs enable assessments of the effectiveness of different programs. While this has more traditionally been conducted for time-of-use programs and to assess their impact on consumer energy consumption, the same rigor must apply to using DERs. Baselining can be conducted by using pre-DER-install, weekends, day-off, and low-solarresource days depending on the type of DER program. Comparing populations of DERs can easily show aggregate behavior; however, being able to pinpoint an individual DER performance will become important for providing performance feedback and calculating remuneration for program participation. AMI for Evaluating Smart Inverter Operation Since 2016, the National Renewable Energy Laboratory (NREL) and Hawaiian Electric have partnered on many aspects of AMI analysis and the extraction of new value. One specific instance of using AMI for DER operation that NREL and Hawaiian Electric have been investigating is the use of smart inverter grid support functions. Volt-var and volt-watt have been required to be used in Hawai'i by the Hawai'i Public Utilities Commission under Hawai'i's interconnection tariff, Rule 14H. Verifying customer interconnection for the activation of volt-var by inverters is challenging given the technical and economic obstacles of setting up communications to-and getting access to- customer inverter data. A potential alternative implemented by Hawaiian Electric is using AMI meter reactive power (var) and voltage data to verify the activation of -0.5 -1 -1.5 -2 -2.5 -3 -3.5 -4 -4.5 -5 1 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.1 Voltage per Unit Figure 5. A scatterplot of voltage and reactive power from AMI data from a customer billing meter. Volt-var operation from a BTM smart inverter can be delineated in the scatter. 62 IEEE Electrification Magazine / DECEMBER 2022 Voltage Offset From AMI Meter to Inverter Terminals Expected Volt-Var Curve TABLE 1. The visibility of DER disaggregation under different metering options for ac-coupled and dc-coupled solar PV + storage systems. BTM Disaggregation Capability Meters Present Solar PV + Battery Coupling DER Billing Meter AC coupling x x x x x DC coupling x x x x Generation Meter x x x x x x x x x x DER Storage Meter Backup Load Panel Meter WholeNet Load x x x x x x x x x x Home Load Separated Main Load Panel Separated Backup Load Panel Solar + Storage Solar + Storage + Backup Load Panel Solar PV x x x x x x x Each row gives the number of meters present (columns in blue) for possible metering configuration and the level of disaggregation achievable (columns in green). x x x x x x x x x x x x x x Storage Var (kvar)