Dear Mwende,
1. The solar multiple (under "Heliostat Field" on the System Design page) determines the receiver's nominal thermal power. It is the ratio of the receiver thermal power to the cycle thermal power. For a system with no storage, the solar multiple should be close to or equal to one.
The heliostat field multiple input is not used by the molten salt power tower model, so you can ignore it. We will remove it in the next update to SAM 2017.1.17.
2. Can you tell me specifically where in Help you saw mention of the fossil dispatch mode? The molten salt power tower model does not include an option for fossil backup. The fossil backup system costs are included on the System Costs page because the System Costs input page is designed to work with both the molten salt power tower model and the direct steam power tower model. The latter includes options for modeling fossil backup.
3. It is not possible to model a power tower system with a cavity receiver in SAM 2017.1.17. Please see this post for more details:
sam.nrel.gov/node/70062
4. In general, you can find information about costs on the
System Costs page
, but the documentation there of power tower costs does not include fossil backup costs.
5. Again, for information about system costs and SAM, please see the documents listed on the
System Costs page
.
Best regards,
Paul.
