Renewable Energy Zone (REZ) Toolkit


The Greening the Grid platform serves as a technical assistance resource, offering a comprehensive range of tools and guidance to assist nations in implementing cutting-edge strategies for power system modernization and facilitating the integration of clean energy technologies, such as variable renewable energy technologies.

The resources provided are carefully selected to cater to the specific requirements of partner nations. They encompass a range of analytical tools, training materials, and information products.

Renewable Energy Zones (REZs) refer to certain geographical regions characterized by abundant and diverse renewable energy resources, including wind and solar power. These places include favorable topographical features and land use designations that make them appropriate for the construction of renewable energy projects. Furthermore, REZs have garnered significant attention and interest from various project developers. These regions can be utilized for the identification of novel transmission lines that facilitate the advancement of economically viable, grid-interconnected renewable energy systems.

The REZ Transmission Planning Process refers to the methodology employed for the planning of transmission infrastructure in a Renewable Energy Zone (REZ).

The REZ transmission planning process is a methodological framework designed to facilitate the integration of regions characterized by abundant renewable energy resources (REZs) into the existing power grid infrastructure. The aforementioned procedure facilitates the strategic development, authorization, and construction of transmission infrastructure in order to gain access to regions characterized by abundant high-quality resources, favorable topography, designated land-use, and evident developer enthusiasm. This process plays a crucial role in ensuring the dependable and cost-effective integration of renewable energy sources. The REZ approach has the potential to be customized and used within the existing transmission approval procedures of any given country.




Scale of implementation

Greening the Grid is supported by the U.S. Agency for International Development (USAID) and is managed through the USAID-NREL Partnership. The REZ process can be adapted to any country's normal transmission approval processes.



REZ toolkit is a central collection of online analytical tools and document templates in a web platform  that can support practitioners in deploying the REZ process.


Phase of solution

The REZ Toolkit is a solution that primarily focuses on the design and optimization phase of energy systems. It helps users in the initial  evaluate different system configurations, analyze the techno-economic and financial  feasibility of various options, and optimize the design for cost-effectiveness and performance.


Target audience

Policymakers, planners, and system operators around the world have used variations of the REZ process to chart the expansion of their transmission networks and overcome the barriers of traditional transmission planning.

Key features-functionality

The REZ Toolkit consists of:

  1. Renewable Energy Data Explorer: the flagship tool of the RE Explorer, facilitates renewable energy decision making, investment, and deployment through a dynamic, online analytical tool. RE Explorer provides renewable energy data, analytical tools, and technical assistance to developers, policymakers, and decision makers in developing countries.

  2. Multi-criteria Analysis for Planning Renewable Energy (MapRE): provides a framework for the systematic identification and valuation of areas for RE development–focusing mainly on solar and wind technologies–for developing countries. By providing government officials, regulators, utilities, and other stakeholders information about multiple siting criteria for possible REZs in the form of reproducible planning tools, the MapRE initiative seeks to improve the planning of low-carbon, cost-effective, socially and environmentally responsible energy systems.

  3. System Advisor Model (SAM): SAM from NREL is a performance and financial model designed to facilitate decision making for people involved in the renewable energy industry including policy analysts, technology developers, project managers and engineers, and researchers.

  4. PVWatts® Calculator: helps users estimate the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. Private sector installers and others can use it to easily develop estimates of the performance of potential PV installations.

  5. Energy Zones Mapping Tool (EZMT):a free online mapping tool to identify potential energy resource areas and energy corridors in the United States. EZMT is a map-based tool for identifying areas within the U.S. that may be suitable for power generation and energy corridors and considers traditional generation and renewable energy resources. The platform also includes tools to generate and analyze potential transmission corridor routes.

References & Sources for Further Reading


  • Greening the Grid Renewable Energy Zone (REZ) Toolkit:
  • Lee, N., Flores-Espino, F., & Hurlbut, D. J. (2017). Renewable Energy Zone (REZ) Transmission Planning Process: A Guidebook for Practitioners (NREL/TP--7A40-69043, 1389211; p. NREL/TP--7A40-69043, 1389211).