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HOMER Grid has the ability to model stand-alone systems for resiliency applications. Resilience is defined as the ability for a system to respond to an extended, multi-day utility outage. During a resilience event, only the critical electrical load and the thermal load, if applicable, are served.


You can find Resilience listed under Utility as shown below.




Resilience is the ability to serve critical electrical loads during a multi-day outage. Only critical electrical loads and the thermal load, if applicable, will be served during an outage. Non-critical loads can be entered in the Non-critical Load menu.




Note: To run a model with resilience outages, include a generator with a capacity capable of serving the critical load. Specifically, the generator capacity must be greater than or equal to the “Electrical Load”(as it is referenced in the menu) or the “Critical Load” (as it is referenced in the Schematic).


The purpose of modeling resilience as a value stream is to account for the costs and the ability to operate off-line in an emergency. There are costs associated with running the back-up equipment necessary to serve the critical load. To account for these costs, HOMER Grid explicitly models one year of normal operation and one year of operation including the resilience event. The costs of the system over its lifetime (net present cost, LCOE, cash flow, etc) are a weighted average of the costs during these two simulated years. HOMER Grid  uses the value entered for the “Outage occurs every…” input to determine the weights in the averages used to calculate system cost.


The input variables are as follows:




Outage Duration (days)


The number of days that the grid will not provide electricity.

Start Date


The day of the year and time at which the outage is to start.

“Outage occurs every...” (years)


The period in years at which resiliency events should occur. This entry must be greater than or equal to 1. A value of 1 would indicate that the outage occurs every year.

Generator may operate only during an outage

The generator may operate during an outage, but not during normal, grid-connected operation.

Generator may operate whenever it is economic

The generator may operate both during an outage and during normal, grid-connected operation.


Both the “Outage Duration” and the “Outage occurs every...” inputs are sensitivity variables.


See Also


How HOMER Grid models Resilience

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