Multifaceted Hybrid PV Diesel System

In several of my projects, I need to use different sized Inverters,some of which are not in the Inverter CEC Database. Since the PV modules are also in different orientations, I created separate cases for each of these combinations.
All these cases are part of a single power generation system which is tied to the grid with NO grid feedback. For backup purposes, there is a diesel generator.
I now need to add AC connected Battery Storage to this entire combination. The batteries should be charged from “extra” energy
supplied by the PV modules and/or from the grid during the off-peak time-of-use periods. So, the batteries must, in addition to assisting the generator during grid failure as part of the backup power, also function as a peak-shaving system.
I would appreciate help in setting this up in SAM.

Hi Bertie,

As you know, SAM is not designed to model hybrid power systems, and it assumes that the grid is always available to either absorb excess electricity or deliver electricity when the power system cannot meet the load.

To approximate the performance of hybrid power system, you might try creating a generation profile by combining the electrical output of each of the PV systems you modeled, and using that profile as input to the Generic Battery model.

One way to calculate the combined output of the PV systems would be to use the Combine Systems macro (click Macros under the Simulate button). You can follow the macro instructions to create the "combined" generation profile for a Generic System case as described, but then export the generation profile from the Power Plant page of the Generic System case to a text file, and then import it to a different Generic Battery case.

Another approach would be to write an LK script that creates the combined generation profile.

Best regards,
Paul.

Paul,

I am also modeling a hybrid PV/battery AC coupled system in SAM. I am a bit confused by when you say SAM is not built for hybrid systems. What are the "Battery Storage" performance models then? 

My issue is that it seems I am only adding the inverter for the PV system. I also need to add in the bi-directional inverter for the battery. I am wondering if this is already somehow included in the battery costs. Can you hep[ me with this?

Thanks,
Vikram

Hi Vikram,

We typically use the term "hybrid" to describe a system that combines more than one power source, like PV-diesel, or PV-wind-diesel, etc. Terms like "PV plus storage" describe a power system that includes storage.

For AC-coupled batteries, SAM models the AC-to-DC conversion as a simple fixed efficiency that you specify on the Battery Storage input page under "Power Converters." The conversion of the photovoltaic array's DC output to AC is modeled using the more detailed inverter model with parameters on the Inverter page. SAM models the two conversion processes separately, even when a single bi-directional inverter may handle both conversion processes in the real physical system.

As for costs, please see my reply to your other post at sam.nrel.gov/forum/forum-general/3108 .

Best regards,
Paul.