EnergyPlus can model Solar Collectors and Drain Water Heat Exchangersdirectly but not greywater heat recovery.

You will need to model the greywater heat recovery separately. I suggest modeling it as a DistrictHeating (per @aparker’s comment below).object with a Source Temperature Schedule that you will need to calculate yourself from your hot water assumptions, and then import into your model with a Schedule:File object. You will add this DistrictHeating object to your service hot water loop.