The Calculate button appears on the right end of the toolbar, and is visible from all pages. It changes appearance depending on the status of the current design.
If the current design contains all the necessary components and resources, the calculate button is green. If the design is obviously incomplete (i.e., if a PV is added and no solar resource is defined, or if there are both AC and DC components but no system converter), the Calculate button is gray. See the Required Changes or Suggestions area under the Schematic on the left side of the page to complete the system.
Note: It is possible for the Calculate button to be green, but HOMER cannot find a feasible solutions after calculating.
When you click the Calculate button, HOMER performs the calculation and displays the results on the Results page. You can click the Estimate button before the Calculate button to see an estimate of how long the calculation will take.