Can't run beta and does it fix inverter sizing issue - DC plant/input used for AC load capacity

energysteven
Topic Author
New Member

01 Oct 2012 11:30 #907 by energysteven

Can't run beta and does it fix inverter sizing issue - DC plant/input used for AC load capacity was created by energysteven

We found an issue with the use of inverters - SAM uses the inverter rating as the DC capacity, not the AC capacity.
In otherwords, it's customary for a manufacturer to specify their inverter by the AC load it can carry.
But SAM treats its as the maximum DC plant size.
So we are having problems where if we the inverter right at capacity, SAM actually raises a flag that says we've exceeded the capacity of the inverter.
Also - I tried to download the beta and run it and it complains that I can't run it on a 64-bit machine.

Please Log in or Create an account to join the conversation.

Paul Gilman
Platinum Member

01 Oct 2012 16:23 #908 by Paul Gilman

Replied by Paul Gilman on topic Can't run beta and does it fix inverter sizing issue - DC plant/input used for AC load capacity

Hello,

SAM runs on both 32-bit and 64-bit versions of Windows. I am running the current Beta version (SAM 2012.9.27) on my 64-bit Windows, and we haven't heard (yet) from anyone else having trouble installing the Beta version, so I am not sure that is the problem.

Can you tell me what edition of Windows you are running (Home Premium, Professional, Ultimate)?

Regarding the PV system sizing message, SAM does compare the array DC capacity to the inverter AC capacity to display the message on the Array input window. At this stage in your analysis, there are no simulation results, so SAM has no information about how well the array and inverters are matched during operation given weather conditions at the site. Our intention is to have SAM give you some rough feedback before you run simulations about the relative sizes of the inverters and array. After you run simulations, you can check the top right corner of the Results page for the warning icon, which SAM displays when there are potential problems with array and inverter matching based on data from the hourly simulation results.

The red message text on the Array page is informational -- it displays the relative sizes of the array and inverter, but does not prevent you from running simulations. In most cases, it is appropriate for the inverter and array capacities to be different.

Best regards,
Paul.

Please Log in or Create an account to join the conversation.

energysteven
Topic Author
New Member

01 Oct 2012 18:32 #909 by energysteven

Replied by energysteven on topic Can't run beta and does it fix inverter sizing issue - DC plant/input used for AC load capacity

WRT Beta Install: I installed the release version with no problems so I just assumed it was with the Beta build.
As to others reporting no issues, I will try to find a work-around for me but again, I went to download just as soon as I got the email notification. I will wait and see if others do complain.
WRT AC vs. DC: That's a problem - what's the point of modeling the inverter if SAM incorrectly reports a warning? For example, I went to the AES/PVP website and used their string calculator and my PV was well within the capacity of the unit.

Please Log in or Create an account to join the conversation.

Paul Gilman
Platinum Member

01 Oct 2012 18:58 #910 by Paul Gilman

Replied by Paul Gilman on topic Can't run beta and does it fix inverter sizing issue - DC plant/input used for AC load capacity

I'd like to make sure you get the Beta version installed, but I don't have enough information based on the screenshot you sent to determine what the problem might be. It is puzzling that the Beta version will not install but that SAM 2012.5.11 did. Any information you can provide like the edition of Windows you are using and any other details like when in the installation process you saw the message would help us solve the problem.

I don't think the message is incorrect (it's not really a warning, it's just an informational message). The message is showing the relative capacities of the array and inverters as a percentage:

Array DC Nameplate Capacity / Inverter AC Nameplate Capacity * 100%

Is there a different value that would be more useful to show?

Best regards,
Paul.

Please Log in or Create an account to join the conversation.

energysteven
Topic Author
New Member

01 Oct 2012 20:03 #911 by energysteven

Replied by energysteven on topic Can't run beta and does it fix inverter sizing issue - DC plant/input used for AC load capacity

UPS, Variable Speed Drives, and other Inverters are designed to pickup an AC load. I will use the system inefficiencies to "back into" the actual service, DC or AC, I need to feed my "plant" to support the rated AC load 100%. This is one of those "philosophical" discussions.

I showed the properties dialog to show tried choosing Windows 7 and XP SP3 and I still get that silly message.
I also showed you my Computer properties.

Please Log in or Create an account to join the conversation.

flowtech
New Member

27 Oct 2012 02:35 #912 by flowtech

Replied by flowtech on topic Can't run beta and does it fix inverter sizing issue - DC plant/input used for AC load capacity

energysteven follow these steps and you will not have any problems installing and running the beta SAM

1. Insert a new CDR in your CD drive
2. From the SAM downloads page right click the beta download and select Save Target As and browse to the CD Drive
3. The beta will download to the CD
4. Open the CD and right click on the file name and select properties
5. Deselect all 3 attributes check boxes
6. Click Apply
7. Click OK
8. Double click the file name and it will install OK

regards flowtech

Please Log in or Create an account to join the conversation.

Moderators: Paul Gilman

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

NREL Home

NREL Research

Follow NREL

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.