This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. User Guidance, Caveats, and Limitations of Cambium DatabasesWhen projecting the expansion and operation of the U.S. electric system in coming decades, it is necessary to make various simplifications. Here, we list some important limitations and caveats that result from these simplifications:• Cambium Data Should Not Be the Sole Basis for Decisions: Cambium data sets contain modeled projections of the future under a range of possible scenarios. Although we strive to capture relevant phenomena as comprehensively as possible, the models used to create the data are unavoidably imperfect, and the future is highly uncertain. Consequentially, these data should not be used as the sole basis for making decisions. In addition to drawing from multiple scenarios within a single Cambium set, we encourage analysts to draw on projections or perspectives from other sources, to benefit from diverse analytical frameworks when forming their conclusions about the future of the power sector.• Cambium's Metrics are Derived from System-Wide, Cost-Minimizing Optimization Models: The models that Cambium draws from take system-wide, cost-minimizing perspectives that do not necessarily reflect the decision-making of individual actors, whose actions may not align with system-wide cost-minimization because of differing incentives or information deficits.

This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. U.S. Department of Energy (DOE) reports produced after 1991 and a growing number of pre-1991 documents are available free via www.OSTI.gov.

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Context and Problem DescriptionThe Government of India has set a target of installing 175 GW of renewable energy capacity by the year 2022, which includes 100 GW from solar, 60 GW from wind, 10 GW from bio-power, and 5 GW from small hydropower. Out of 100 GW solar, 40 GW is targeted from rooftop solar photovoltaics (PV). These renewable targets can lead to a new paradigm for power grid planning and operations.Historically, power distribution utilities were designed to serve low voltage loads within their territories, and for decades their planning works were based on the premise that customers only consume power. During this time, distribution utilities learned customer consumption patterns, identified peak, off-peak, and shoulder hours and crafted proficient planning and operational strategies to match them.Over the past decade, solar PV and wind energy adoption has increased at all scales (transmission and distribution), as illustrated in Figure ES-1. Also, recent and anticipated adoption of battery energy storage systems (BESS) and electric vehicles (EVs) are changing the landscape of supply and demand. Some of these emerging technologies are variable in nature and others are not fully understood, thus posing a need for distribution utilities to update the way that they plan and operate their systems.Opportunities and challenges posed by these technologies (solar PV, BESS and EVs) on the power distribution grid are yet to be comprehended, holistically. Typically, wind farms are planned and built at large scale (100 MW to GW) and interconnected to transmission systems. Solar PV, on the other hand, can either be connected to transmission systems at the GW scale or at rooftops at the kW scale. Thus, challenges and opportunities vary significantly depending on the size and point of interconnection (transmission or distribution system). Figure ES-1. Variable renewable resources integrated on the power grid at transmission and distribution levels are posing challenges for distribution utilities www.nrel.gov/usaid-partnership vii www.nrel.gov/usaid-partnership viiiThis track considers renewable integration at bulk grids and assesses their value addition. In order for distribution utilities such as BYPL to make inform decisions when signing power purchase agreements (PPAs), it is crucial for them to understand how much energy and capacity their contracted renewable energy generators can provide. We address the situation faced by utilities by modeling variable renewable energy (VRE) plants from two perspectives: (1) energy production, and (2) capacity credit. Capacity credit describes the percentage of a plant's nameplate capacity that can be reliably counted on to serve load. The capacity credit perspective is illustrated in Figure ES-2, which shows that effective planning includes the possible contributions of VRE. Use of capacity credit unlocks a unique path for understanding the planning reserves provided by solar PV and wind resources. To demonstrate the value from this research, NREL utilized existing knowledge o...

This report is part one of a two-part series that represents a year-long collaboration between the National Renewable Energy Laboratory (NREL) and the Tamil Nadu Generation and Distribution Corporation Limited (TANGEDCO) and Tamil Nadu Transmission Corporation Limited (TANTRANSCO) on power sector planning. This Pathways for Tamil Nadu's Electric Power Sector 2020-2030 report outlines NREL's work with TANGEDCO's electricity sector planning department to develop a model of the state power system and evaluate multiple scenarios of system evolution, given resource constraints, costs of technologies, and power sector policies. A broad stakeholder group comprising TANGEDCO leadership, developers, regulators, and researchers from within the power sector community in Tamil Nadu helped to guide the main objectives of the study and provided technical feedback to the research team. The outcomes of this effort include multiple pathways for power sector growth to 2030 and a robust model of Tamil Nadu's power system that can be used to continually analyze the impact of new policies, regulations, or system changes. The second report in this series will build on the bulk system analysis by focusing on the rapidly transforming distribution network in the state. The report will outline a framework developed by NREL and TANGEDCO's distribution utility to quickly and accurately analyze the impacts of integrating renewable energy (RE) onto Tamil Nadu's distribution system. Together these studies help to prepare Tamil Nadu for a rapidly transforming power system. NREL's partnership with TANGEDCO is the first of several collaborations with India's states to enhance their ability to plan for and effectively manage the transformation of India's power system to higher penetrations of RE. A better understanding of the impacts of this transition allows for better practices, more effective policies, and increased capacity to absorb new technologies. This work is supported by the Children's Investment Fund Foundation.