I have been working with Homer and am unable to figure out how to include Time of Use (TOU) costs for grid power. The impacts of the various TOU periods are critical to determining the cost effectiveness of distributed systems - therefore it is important for performing an accurate model. Is there some way to model this?

In the Add/Remove window, you need to indicate that the system is connected to the grid. Then a Grid button will appear in the schematic. Click that and on the Rates tab, choose Scheduled rates (the default) and click the Add button to add a second rate. You can define as many rates as you wish. You can set the power price for any rate by double clicking on it, and you define the time at which each rate applies by 'drawing' on the Rate Schedule. Follow the Step 1, Step 2, Step 3 instructions on the Rates tab, and make sure you click the Help button for a complete explanation and an example.