REopt Web Tool Software Updates

NREL updates the REopt® web tool on a regular basis. Review REopt's software update history below.

Web Tool Development Plans

NREL developers are working on the following Fiscal Year 2023 REopt web tool features:

  • Portfolio screening capability
  • Grid emissions rates from NREL's Cambium data set
  • Geothermal heat pump updates (hybrid systems, central plants)
  • Energy Resilience Performance tool (reliability metrics and other resilience model updates)
  • Inflation Reduction Act incentives and tax model updates
  • Updated default values.

Additionally, updates are being made to REopt's application programming interface (API) and Julia package, which offer programmatic access to REopt's capabilities and open source code.

REopt development plans are subject to funding allocations and may change throughout the fiscal year.


September 2023: Hybrid Geothermal Heat Exchange Technology

NREL has added a new capability to the REopt® web tool to help commercial building owners and energy managers more effectively evaluate the costs associated with geothermal heat pump (GHP) projects: the ability to integrate hybrid heat exchange with GHPs. Read the story: NREL Enhances REopt Web Tool With Hybrid Geothermal Heat Exchange Technology.


February 2022: REopt Isn't "Lite" Anymore

This version of the REopt web tool drops the “Lite” from its name to better reflect the tool's comprehensive techno-economic optimization capabilities. The REopt web tool helps users evaluate the economics of distributed solar, wind, battery storage, combined heat and power, geothermal heat pumps, modeled greenhouse gas reductions, and more. NREL’s REopt development team continues to work with partners to explore new technologies and challenges that sites, communities, and utilities are facing—and to build new capabilities to address those challenges. Read the story: REopt Is Not Lite Anymore: Techno-Economic Optimization Tool Brings Enhanced Renewable Energy Optimization Capabilities to Every User.

January 2022: Greenhouse Gas Emissions Accounting

This version of the REopt web tool helps users calculate health-related emissions from grid-purchased electricity and on-site fuel burn, and total life cycle emissions, which include future changes in grid emissions intensity. Optional total life cycle emissions costs help estimate potential social, climate, and public health cost savings related to an energy project's CO2, NOx, SO2, and PM2.5 emissions impacts. Users can calculate the least-cost pathways to achieve a renewable energy or emissions reduction target at a particular site and quantify the associated investment and savings. The tool includes flexible renewable energy and emissions accounting methodologies, with options to include or exclude exported clean electricity as an emissions offset and/or in renewable energy calculations. Read the story: REopt Targets Emissions for Tomorrow's Cleaner, Healthier Built Environment.


December 2021: Geothermal Heat Pumps and Off-Grid Modeling

This version of the REopt web tool allows users to evaluate the impact of converting conventional heating and cooling systems to geothermal heat pumps to lower the overall cost of energy. Facility managers can consider geothermal heat pumps as a strategy for reaching site decarbonization goals by electrifying loads and meeting them with onsite renewable energy, and see how a geothermal heat pump retrofit impacts economics and sizes for distributed energy resources. Read the story: REopt Goes Underground To Elevate Facility Energy Savings and Resilience.

Users can also "turn off" the grid as a technology to evaluate off-grid microgrids, include optional operating reserve requirements based on hourly load and solar generation, and specify a percentage of total annual load that needs to be met.

February 2021: Combined Heat and Power, Third-Party Financing, Enhanced Utility-Rate Modeling, and Scenario Comparisons

This version of REopt Lite® allows users to model and size combined heat and power (CHP) systems alone, compare CHP to renewable energy and battery storage options, or leverage all three of these systems in a complementary manner for energy efficiency and resilience. The U.S. Department of Energy's (DOE's) Advanced Manufacturing Office (AMO) funded the REopt Lite CHP project, building on the existing REopt Lite model funded by DOE's Federal Energy Management Program (FEMP). Along with the AMO-funded CHP capabilities, REopt Lite released several new FEMP-funded modeling capabilities for renewable energy projects: third-party financing, enhanced utility-rate modeling features, and comparison of different scenario results. Read the story: REopt Lite Adds a Fresh Dimension: Combined Heat and Power.

Older Updates

February 2020: Open Source Software

REopt Lite Open Source lets users explore and customize the code and work with NREL to implement new REopt Lite features. Read the story: REopt Lite Goes Open Source: Now Programmers, Software Developers, and Researchers Can Access the Code Behind the Web Tool.

Access the REopt Lite GitHub repositories.

December 2019: Downloadable Results Report

Version 1.5.1 of REopt Lite includes a new downloadable results report that allows users to download a PDF version of a saved site evaluation.

October 2019: Resilience Modeling, Diesel Generator Sizing, Load Profile Dashboard, Utility Rate Help, International Guidelines, and Updated Cost Assumptions

Version 1.5 of REopt Lite includes a new diesel generator optimization feature and new resilience graphics that show the expected performance of a system over a range of outages starting at different times of the year. Users are now guided to the most likely utility rates based on their location, load, and the utility's most common rates. A new load profile dashboard allows users to upload and save custom typical and critical load profiles, and new international guidelines give users tips for using REopt Lite at international sites. Default values for technology costs have been updated based on the latest market reports. Read the story: REopt Lite Evolves To Address User Priorities: New Tool Features Help Building Owners Further Explore Costs and Benefits of Resilience and More.

April 2019: PVWatts and Solar Resource Data Set Upgrade

Version 1.4.1 of REopt Lite includes updated solar photovoltaic (PV) system performance data with an upgrade to PVWatts 6, which incorporates additional international solar resources from the National Solar Radiation Database (NSRDB) data set.

March 2019: Custom Hourly Rate Tariffs and Integrated Critical Load Builder

Version 1.4 of REopt Lite includes custom hourly utility rate tariff capabilities and an integrated critical load profile builder, for a more detailed energy analysis without leaving the tool. The latest update includes a wide range of existing or hypothetical utility rates and helps identify systems that can sustain specific critical loads during a site outage. Read the story: REopt Lite Adds Custom Electricity Rates and an Integrated Critical Load Builder.

November 2018: Wind Module, Custom Monthly Rate Tariffs, Critical Load Builder, and User Dashboard

Version 1.3 of REopt Lite includes a new wind optimization module, custom monthly utility rate tariffs, a link to the SolarResilient critical load builder, and a new user dashboard. These features allow users to evaluate the economic viability of distributed wind alongside solar PV and battery storage, and further customize cost savings and resilience analyses. The user dashboard lets users log in, save their optimization results, and view previous runs. Read the story: REopt Lite Adds New Energy Optimization Capabilities with Wind, Custom Rate Tariff, Critical Load Builder, and User Dashboard.

June 2018: Enhanced Resilience Features

Version 1.2 of REopt Lite includes enhanced resilience analysis capabilities that allow building owners and energy managers to size PV and storage systems to meet a specified outage duration, and compare systems sized for optimum savings to systems sized for resilience. Users can also explore the impact of microgrid upgrade costs and avoided outage costs on project economics. Read the story: Enhanced Resilience Features Help REopt Lite Users Size Solar+Storage Systems to Support Critical Building Loads.

March 2018: Application Programming Interface

Version 1.1 of REopt Lite includes a new application programming interface (API) that lets users and software developers programmatically interface with the REopt Lite web tool. The API can be used to evaluate multiple sites and perform sensitivity analyses in an efficient manner, and integrate REopt Lite capabilities into other tools. Read the story: REopt Lite's Application Programming Interface Boosts Solar+Storage Analysis Flexibility.

In addition to the API release, REopt Lite developers added a downloadable dispatch strategy and additional utility rates to the web tool.

September 2017: REopt Lite's Initial Release

Version 1.0 of the REopt Lite web tool, deployed on September 29, 2017, helps building owners evaluate the economics of grid-connected PV and battery storage at commercial sites. It identifies the optimal PV system size and battery dispatch strategy to minimize the life cycle cost of energy at a specific site, and estimates the amount of time a PV and battery system can sustain the site's critical load during a grid outage.

For the first time, REopt Lite provides public access to a subset of NREL's comprehensive REopt model, and allows users to run their own site-specific, optimized, and integrated renewable energy decision analysis in order to accelerate renewable energy and storage project development and deployment. Read the story: New REopt Lite Tool Allows Building Owners to Optimize PV and Battery System Sizes.

Questions About the REopt Tool? Try the User Forum

The REopt User Forum contains frequently asked questions about using the REopt web tool. Browse and search discussions by topic and sign in to join discussions, ask new or follow-up questions, and leave comments and feedback.