Annual outputs with different inverters

I try to predict the annual output of a simple system PV + inverter.
The PV is the Canadian Solar CS6K-260P.
When I check it with the SE 7600A-us(240V) 240V [cec 2013] the annual output was 13,795kWh
And when I check it with the SE 7600A-us(240V) 240V [cec 2016] the annual output was 7,951kWh
(Nothing but the inverter was changed)
Does the output difference seem normal?

Thanks
Yoav

Dear Yoav,

Thank you for the message.

I was not able to replicate those results. Could you attach the .sam file that generated those results to your original post above, or [url=mailto:sam.support@nrel.gov?subject=Forum@20Question t=_self]email it to me[/url]?

Best regards,
Paul.

Dear Yoav,

Thank you for uploading the file.

The reason you get different results using the different versions of that inverter is that the 2013 version does not have data for the maximum and minimum rated MPPT voltage, while the 2016 version does.

That means that SAM cannot estimate losses due to voltage clipping when the array operating falls outside of the MPPT voltage window (100 - 480 VDC for the 2016 version).

When you choose the 2016 version, you should see a message about the string voltage exceeding the maximum rated voltage on the System Design page. You can also see the effect of clipping in the results by going to the Losses tab on the Results page.

To avoid the clipping loss using that combination of module and inverter, you might try using two strings of 16 modules instead of one string of 32 modules. That reduces the array operating voltage and minimizes clipping losses. (The nominal array Voc is still higher than the nominal inverter maximum voltage, but the operating voltage only rarely exceeds the maximum -- you can see that by plotting "Subarray 1 Operating Voltage," "Subarray 1 Open circuit voltage," and "Inverter DC input voltage" on the Time Series tab of the Results page.

Best regards,
Paul.