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Multiple Orientations - Low Production?


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Hey guys,

I have recently modeled my companie's projects in PVsyst to get a more accurate production estimate for O&M. The .7 derate used in PVWatts by previous employees looks good when comparing production, but is not good when trying to diagnose if a system is actually producing like it should.

Nevertheless, all went well until I modeled a project we just actually got PTO and onto the grid. It is a commercial standing seam roof. Here are some key details.

Pitch : 5deg

Azimuth: 167 & 357 deg (or as PVsyst likes, -13 and 167 deg)

South facing roof:

76 strings of 11 Canadian Solar CS6X-310P

North facing roof:

93 strings of 11 Canadian Solar CS6X-310P

DC System Size = 576.29 kW

Inverter: Solectria Renewables SGI 500kW 480 VAC


All my other simulations took only a few seconds to complete, but this simulation takes about 7-10 minutes to run. Upon completion, the report shows a tremendous amount of losses. Some of the notable ones are:

Ohmic Wire Losses: 29.5 %

Mixed Orientation Mismatch: 5.5%

Inverter Loss during operation (efficiency): 14.5%

The mixed orientation mismatch seems like a reasonable number but the other two? I defined a 1.5% and 1% loss in power due to wire losses in the detailed losses section and I had that set for every project I modeled over the past week.

I seemed to have stumped the other engineer on staff with this as well so any advice is appreciated. I have uploaded the files as well, but I am not sure which ones you need.


P.S. I had included the meteo file in the zip but it was just over the maximum size. This project was modeled using the Boston meteo file.

FTE 330.zip

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