EVI-EDGES: Electric Vehicle Infrastructure - Enabling Distributed Generation Energy Storage

NREL's EVI-EDGES Model identifies the optimal design and energy flows for thermal and battery behind-the-meter-storage (BTMS) systems based on climate, building type, and utility rate structure.


EVI-EDGES evaluates how integrated systems can unlock additional value for building owners, utilities, and electric vehicle (EV) drivers—at the same time, across the U.S.

To support BTMS research and deployment, NREL researchers developed the EVI-EDGES model to determine the optimal system designs and energy flows for thermal and electrochemical BTMS with on-site solar photovoltaic (PV) generation for various climates, building types, and utility rate structures.

To allow researchers and developers to identify pathways to meet cost and performance targets, EVI-EDGES focuses on:

  • Levelized cost of charging (LCOC)
  • Total system energy use and efficiency
  • Resiliency and flexibility of the storage system.

Integrated Multi-Tool Design

EVI-EDGES integrates four NREL and U.S. Department of Energy analysis tools to allow for detailed simulation of the cost and performance of BTMS systems:

REOPT: Renewable Energy Integration and Optimization estimates optimal ranges for sizing at each site

SAM: System Advisor Model incorporates detailed battery lifetime models and cash flow outputs

EnergyPlus and OpenStudio allow for detailed simulations of the use of thermal energy storage in five building types (corner charging station, retail big-box grocery store, fleet vehicle depot, commercial office building, multi-family residential).

This multi-tool framework enables EVI-EDGES to provide a complete picture of the interaction between components at physics-based resolution.

EVI-EDGES implements a multi-step process to answer research questions and identify the lowest LCOC. Researchers generate baseline load profiles for the building and EV charging stations during the pre-process stage and identify key inputs such as system costs, utility rates, building loads, and EV charging requirements.

Integrated Simulation Inputs

The EVI-EDGES model uses these inputs to run an integrated simulation in three parts:


Suggests preliminary parameter space and sizes for the stationary battery system and PV system that maximize the value of the total system

Model system and component variations

Uses high-fidelity, physics-based models of load, generation, and storage systems to increase the accuracy of electrical power and heat transfer calculations

Explores impact on LCOC using varied component costs, utility rates, location, and charging demand


Identifies key system characteristics such as PV, battery, and TES sizes

Reports minimized LCOC results

Provides time-series outputs of energy flows across the system

Data Visualizations

Detailed visualization allows for further analyzation of the EVI-EDGES results during the post-process stage. Users can analyze which parameter yields the lowest LCOC and identify potential sensitivities.

Data visualization graph compares the impact of the BTMS system based on the size of solar panel PV (kilowatt) and the size of battery (kilowatt hours) to determine the minimum LCOC with the system (cents/kilowatt). Without the system, the LCOC is 40.9, and the minimum LCOC with the system is 29.0.
Example EVI-EDGES results: Impact of the use of behind-the-meter storage and PV to reduce utility costs and the cost of EV fast-charging.
Line graph shows the daily profile of energy flows within a BTMS system based on power demand (kilowatts) as compared the time (hours) for different system configurations: without system (EVs and building), without system (building), with system (electricity sold), with system (electricity purchased), with system (battery and discharge), and with system (solar PV).
Example EVI-EDGES results: Daily profile of energy flows within the BTMS system, showing how batteries and thermal energy storage are dispatched to reduce utility costs and the cost of EV fast charging.

Clean Energy Adoption Spurs Need for EVI-EDGES

Several fundamental and watershed changes in the transportation, electrical, and building sectors are happening simultaneously.

  • Buildings must serve significantly more energy needs—such as grid services, EV charging, electric generation, space conditioning, energy storage, and resiliency—than before.
  • Rapid EV adoption could have significant and potentially negative effects on grid infrastructure and buildings operations.
  • High penetration of solar photovoltaic generation installed on buildings are leading to new challenges for building interactions with the electric grid.
  • New wind and solar installations are market-competitive, creating new challenges for utilities.
  • Energy storage costs are rapidly declining, enabling greater use of clean energy.

Understanding the intersection of these changes is essential for optimizing the economic, social, and climate benefits.

Related Tools

EVI-Pro: Electric Vehicle Infrastructure – Projection Tool

EVI-EnSite: Electric Vehicle Infrastructure – Energy Estimation and Site Optimization Tool


Margaret Mann

Group Manager III, Decision Support Analysis