Distributed energy resources under net metering: optimal decisions, incentives and aggregation

This monograph develops a unified analytical and computational framework for prosumer decision-making, regulatory tariff design and distributed energy resource (DER) aggregation and coordination under a generalized net energy metering (NEM) tariff structure called NEM X. NEM X captures existing NEM tariff designs by incorporating differentiated import and export rates, flexible loads and storage decisions. A key message of this work is that the grid is shifting from forecasting demand to schedule generation, to forecasting generation to schedule demand; moving flexibility from the supply side to the demand side. The evolution from NEM 1.0 to NEM 3.0 and beyond underscores this shift, with profound implications not only for utility cost recovery but also for DER scheduling, the viability of aggregation and the distribution of costs, welfare and market potential. These changes highlight the urgency of efficient incentive mechanisms and innovative DER arrangements such as energy communities and DER aggregation. The authors first analyze prosumer decisions under NEM X, showing that optimal consumption follows a two-threshold policy yielding net-consuming, net-producing and net-zero modes. Optimal consumption decisions are renewable-informed: greater renewable output and lower export rates encourage higher self-consumption. With storage, prosumers jointly optimize demand and battery use, further reducing grid imports and exports. To make the co-optimization tractable, especially for large-scale DER scheduling, the authors introduce a linear-complexity algorithm that enables scalable scheduling with near-optimal performance. While prosumers seek to maximize individual benefits, regulators and system operators face the challenge of designing tariffs that balance economic efficiency, equity and long-run sustainability in distribution systems increasingly shaped by rooftop solar, flexible loads and storage. To that end, the authors address the regulator’s decision problem using a stochastic Ramsey pricing framework that balances efficiency, equity and revenue adequacy under uncertain generation. NEM tariff parameters critically affect cost shifts, DER adoption dynamics and payback periods, shaping both short-run welfare distribution and long-run sustainability. Finally, the authors design mechanisms for DER sharing and aggregation in energy communities. The authors propose Dynamic NEM (D-NEM), a pricing mechanism that aligns individual incentives with community welfare, guarantees a higher surplus for all members and satisfies the principle of cost-causation. Extensions account for dynamic operating envelopes (OEs) imposed by distribution system operators, ensuring grid compliance. A cooperative game formulation further shows that DER sharing under NEM gives higher welfare as the community size grows and admits stabilizing welfare re-distribution rules. Taken together, these results provide a rigorous foundation for guiding the next generation of retail electricity tariffs and DER aggregation and coordination mechanisms. By integrating analytical models of prosumer response under different DER compositions with regulatory design and community-level market mechanisms, this monograph demonstrates the implication of NEM tariff designs on adoption decisions, social welfare and equity. In doing so, it offers a clear pathway for regulators and policymakers to achieve equitable, efficient and reliable DER integration in the evolving high-DER grid. This monograph investigates the control, optimization and mechanism design of standalone and networked energy systems with heterogeneous distributed energy resource (DER) compositions and diverse consumption preferences. Central to this work is the formulation of an inclusive net energy metering (NEM) tariff structure–NEM X–which generalizes key features of existing NEM tariff designs across regulatory jurisdictions. The NEM X framework serves as the analytical foundation for exploring optimal prosumer behavior, DER adoption dynamics and rate-setting strategies by regulators and DER aggregators. The first part of the monograph presents a comprehensive analytical characterization of optimal prosumer decisions under NEM X, which allows for differentiated import (retail) and export (sell-back) rates. In the presence of flexible demands and stochastic behind-the-meter (BTM) renewable generation, we demonstrate that the optimal consumption policy adheres to a two-threshold structure, whereby consumption is scheduled as a function of available renewable generation. These thresholds are derived in closed form and computed apriori, enabling tractable, decentralized implementations. When BTM energy storage is introduced, the prosumer’s decision problem becomes a stochastic dynamic program that jointly optimizes consumption and storage dispatch. To mitigate the computational burden of solving this otherwise intractable problem, we develop a myopic co-optimization algorithm that requires no prior knowledge of the underlying probability distributions of the renewable generation. We establish sufficient conditions under which the myopic co-optimization algorithm is optimal. The structural properties of the optimal policy are derived, providing insight into how external factors, such as battery and NEM X tariff parameters, influence endogenous quantities such as flexible load consumption, storage utilization and prosumer surplus. The second part leverages the prosumer decision framework to analyze the regulator’s rate-setting problem. We model the long-run evolution of NEM X tariff parameters (e.g. import/export rates, fixed charges and time-of-use price differentials) using a nonlinear feedback system, where regulators solve a stochastic Boiteux–Ramsey pricing problem subject to revenue adequacy constraints. This formulation accounts for demand and generation uncertainties as well as behavioral feedback from prosumer response. We evaluate the welfare and equity implications of several NEM X variants using both real and synthetic data. In particular, we quantify the impact of tariff design on (i) total social welfare, (ii) cross-subsidization between prosumers and nonprosumers and (iii) the payback period of DER investments – factors that jointly shape the equilibrium DER adoption trajectory in both the short and long run. The third part addresses the design of DER coordination mechanisms within energy communities, accounting for network constraints and economic incentives. We begin with a bi-level Stackelberg framework for an energy community in which a community operator (leader) designs pricing rules to maximize social welfare, while prosumer members (followers) respond by optimizing individual consumption. Within this framework, we propose Dynamic NEM (D-NEM) – a decentralized, ex-ante pricing mechanism that dynamically sets the community export price based on aggregate DER output. D-NEM aligns individual incentives with collective welfare, ensuring efficiency, budget balance and group rationality. We further extend D-NEM to account for physical network constraints, enabling scalable implementation in real distribution systems. Building on this decentralized market mechanism, the final part of the monograph shifts focus to a cooperative formulation of energy communities, where DER assets are jointly managed behind a regulated utility meter under a general NEM tariff. We model the community as a cooperative game in which prosumers coordinate DER scheduling through either centralized or decentralized schemes. In both cases, we prove that the cooperative game is superadditive, implying that the grand coalition achieves maximum collective welfare. Moreover, we establish the balancedness of the game, ensuring that redistribution mechanisms exist to prevent any subset of prosumers from defecting.