Tips For System Sizing

Didn't realize that their combination is critical. Have to do some research on this!
Thank you!

I can't figure out how to eliminate the MTTP issue.  Please help!  I've attached the .sam file and a Word file with the results from the "System Sizing" Macro

Hello,

Figure 1 of the PV system sizing macro report is helpful for determine what is causing excessive MPPT voltage clipping. SAM clips the inverter input voltage to the minimum MPPT voltage when the array votlage falls below the inverter's minimum MPPT voltage rating, and to the maximum MPPT voltage when the array voltage exceeds its maximum MPPT voltage rating. In your case, the minimum operating voltage is less than the minimum MPPT voltage rating (orange line in the graph), so you can see that the clipping is being caused when the array voltage is too low.

 

To reduce clipping, you can either choose an inverter with a lower minimum MPPT voltage rating, or increase the number of modules per string. For example, I tried 20 Gamesa Electric PV4300 inverters. This inverter has a minimum MPPT voltage rating of 875 VDC. Note that you can manually overrid the inverter MPPT voltage ratings by changing the valueas at the bottom of the System Design page.

The system sizing macro is intended to help you size the system -- you should run a simulation and use the information on the Results page to evaluate your system design. For example, on the Time Series tab, you can plot "Inverter clipping loss DC MPPT voltage limits (kW)" and "Subarray 1 Operating DC voltage (V)" to see when the voltage is being clipped, and, on the Data Tables tab, you can display those variables and others like "DC inverter MPPT clipping loss (%)" and "Inverter clipping loss DC MPPT voltage limits (kWh/yr)."

Best regards,
Paul.
 

So no matter what I do, I can't get rid of the red on page 1 of the report nor get the green bars to the left of the orange line on page 2.

Why can't I upload files that are only 5KB if the note on your page says Max 10 MB?

So again, "There are O modules from the same manufacturer and O modules in the library from different manufacturers".  If there are zero in your library than how do I fix my issue?  When I increase or decrease the numbers of either modules or Inverters, either the green bars move further to the right or the "estimated Power" bars turn red or orange.  I've run dozens of simulations/sizing macros, to no avail.

Hello,

When you use the "CEC Performance Model with Module Database" option on the Module page, the sizing macro does not suggest other modules from the library because that option does not use the module library. If you want the macro to suggest modules, you should choose the "CEC Performance Model with User Entered Specifications."

There is a bug in the PV sizing macro that causes the colors in the table to be incorrect. We will fix this for the next version of SAM. In the meantime please this workaround solution:

1. Download the "System Sizing.lk" file from this GitHub page:  github.com/NREL/SAM/blob/sam-2102-pv-sizing-macro-annual/deploy/runtime/macros/Flat%20Plate%20PV/System%20Sizing.lk .
2. If SAM is running, close it.
3. Replace the "System Sizing.lk" file in the "/runtime/macros/Flat Plate PV" folder of your SAM installation (c:\SAM\2025.4.16 by default in Windows, see sam.nrel.gov/forum/forum-general/2776-sam-installation-folder.html for Mac or Linux) with the version you downloaded.
4. Start SAM, open your .sam file and try running the macro.

Best regards,
Paul.