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Spec. Annual Yield reduction

Karina Suharevska

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I made one solar plant with 1820 solar panels, each 450W. Total output 819kW with spec.annual yield 855,61 kwh/kwp. Grid feed in 700 955 kwh/year.

Then I changed all 1820 panels to 460W. Then total output was 837,20kW with spec.annual yield 831,37 kwh/kwp. Grid feed in 696 232 kwh/year.

My question - why the spec.annual yield and grid feed in drop off so much ? I am concerned because, the power of one module became bigger, but the spec. annual yield decreased.


Please see file attached.


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Hello Karina Suharevska,

at first I thought that it might be rounding errors, but are you sure that you did send me the correct files? Even with minute values simulation I cannot reproduce your posted results:



A look into the PV System Energy Balance shows a difference in orientation and inclination, so it seems not only the modules have changed. The losses for low-light performance and DC/AC Conversion differ a lot.


My project files seem both be different from the ones where you did take the screenshots of. Might you be able to send the correct files?

Kind regards,

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The screenshot files are incorrect. Please see screenshot below and use them for comparing.



These are correct screenshots. Inclination and orientation seems the same. I have question about:

1) Low-light performance - why with 460W panels its much bigger value than for 450W panels.

2) why spec.annual yield differs?

3) DC/AC conversion differs because of changing inverters?


Olimpia 9.5._1820gab.pdf Olimpia_8.9_450W.pdf

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