I wish to incorporate a number of sources into my design and will be using a combination of DC and AC converters. Do you have a suggestion as how to go about incorporating losses from more than one converter? Assuming I wish to have a DC bus and attach a number of AC or DC sources with likewise differing loads, is there any way to incorporate conversion losses for each connected device? Would it be possible to feed back the results from one system into another?

If you intend to model an AC power source connected to a DC bus, then I recommend you model the power source plus its dedicated rectifier as a single DC power source, whose cost and performance account for the presence of the rectifier.

For example, if you intend to model a 2 kW AC wind turbine that will feed power to a DC bus through a dedicated 90% efficient rectifier, that would look to HOMER like a 1.8 kW DC wind turbine, so you should model it as such.

If the turbine itself costs $6000 and the rectifier costs $1800, then you should enter a cost of $7800.

Using a similar approach you could model multiple AC sources (generators, a hydro turbine) each supplying a DC bus through their own dedicated rectifiers.  And you could at the same time model multiple DC sources supplying the same DC bus.  That DC bus could in turn supply AC and/or DC loads.