I use Homer as a teaching aid but am unsure of a few things: Power factor in load. My understanding is that apparent power reflects back into the dc side of an inverter and draws true power from the battery eg. 1kVA apparent power load of PF 0.5 is actual power of 0.5kW in load but battery must deliver 1000W. If this is the case then apparent power must be used when developing a load profile. Do you agree? If not what is the answer?

Yes, one should use the apparent power (VA) for the system load entered into the models. In very simplistic terms lower power factors require more input energy to supply the loads.

There is no power factor with direct current, its just Volts times Amps, and so the power needs on the DC side of the inverter are to supply the apparent power needs on the AC side of the inverter. In renewable systems this can be a problem since the ballasts in poor quality florescent lighting tend to have poor power quality.

As an additional note - some inverters don't control on apparent power - so can become overloaded when supplying loads with low power factors.