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Input Variable |
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% |
The maximum annual capacity shortage is the maximum allowable value of the capacity shortage fraction, which is the total capacity shortage divided by the total electric load. HOMER considers infeasible (or unacceptable) any system with a higher value of the capacity shortage fraction.
Allowing some capacity shortage can change the results dramatically in some cases. This might happen if a very high peak occurs for a very short time. If the maximum annual capacity shortage is set to zero, HOMER sizes the system to meet even this very high peak load. This could mean that the system has to include large, expensive equipment that is not fully used most of the time. If you allow a small amount of capacity shortage, HOMER could choose to install smaller, less expensive equipment that would be able to supply all but that peak load.
Note: If you set each of the four operating reserve inputs to zero, the capacity shortage fraction is equal to the unmet load fraction.
See also: