The chart shows the cumulative effect of resilience costs and benefits on the project's net present value. Source: NRELThe U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) has rolled out improvements to Reopt Lite, a web-based tool for solar photovoltaics (PV) and battery storage optimization. The tool now offers enhanced resilience analysis capabilities that allow building owners and energy managers to size PV and storage systems to meet a specified outage duration. By giving users the ability to compare the sizing and costs of a resilient system with a system sized to maximize savings, the new release of Reopt Lite will help decision-makers identify potential cost gaps and balance their economic and resilience goals.

The new resilience inputs allow users to specify a site’s critical load as a percentage of the typical load, or they can upload hourly critical load data. An interactive plot of the critical load helps users determine which outage period to evaluate based on statistics such as average load, minimum load, maximum load and the days on which minimum and maximum loads occur.

The tool provides users with the option of including existing PV systems and diesel generators in the resilience analysis. Users can specify the size of the existing PV system or diesel generator, along with the gallons of fuel available and other inputs such as the fuel burn rate and minimum loading. It can also be used to evaluate a major outage that might occur only once over an analysis period, or a typical outage that might occur annually.

Results from Reopt Lite allow building owners and energy managers to compare systems sized for optimum savings to systems sized for resilience, and explore the impact of microgrid upgrade costs and avoid outage costs on project economics.

Reopt Lite's enhanced resilience features have also been implemented in the Reopt Lite application programming interface (API). Released in March 2018, the Reopt Lite API allows users and software developers to programmatically interface with the Reopt Lite web tool, evaluate multiple sites and perform sensitivity analyses in an efficient manner, and integrate Reopt Lite capabilities into other tools. In addition to the API release, Reopt Lite developers have added a downloadable dispatch strategy and additional utility rates to the web tool.