Michele Oliosi

Hi ! Indeed, currently the backside and reflected irradiance modeling is quite picky. The idea is that the geometry it assumes is that of trackers on flat ground. The discrepancy between 3D scene and backside irradiance model therefore leads to this message, to warn users of the possible inaccuracy. However, there is no alternative model, and the approximation of flat ground is not too bad if the slope is only 5°. In other words: You can change an advanced parameter to ignore the axis tilt message: Home window > Settings > Edit advanced parameters: I think a good way currently is to build fixed tilt structures first and then use the "transform to trackers" option: This will ensure that you can use the row-to-row slope options which are available for fixed tilt arrays (if I am not mistaken).

I see, I have checked and indeed this is not the case. PVsyst 8 also has the same issue. I have created a ticket to fix this in a future patch.

Pnom without temperature correction means nominal power, and not maximum power. So in your example it is relative to 320kW.

@NGS In case you have a warning due to the average axis tilt not being horizontal: you can override this error in the following way. Home window > setting > Edit advanced parameters: Note that this is only forcing PVsyst to proceed, but the backside irradiance model is still modeling things with a zero axis tilt (which generates a discrepancy with the actual orientation, and means there will be some uncertainty in the results).

Hi ! Which version of PVsyst are you running ? We will make some checks to see if we can reproduce this behavior

If you can, let us know what you find that would be great.

Hi, It's more likely a problem of compatibility of the PVsyst output with the regional format on your Excel/Windows installation. In PVsyst you can try changing the format and see if anything helps There are also more options on Excel, but I'm no expert there:

I put a note in the ticket about this. By the way, to speed up things when you are running several simulations, you can use the representative tracker mode (3D scene > Tools > Trackers diffuse shadings definition). Although less precise if you are doing many iterations it can save much time.

If you follow Daniel's latter examples (1-0.4)/2 = 0.3%? Indeed here you would assume that the loss increases to 0.6% in one year so on average during the first year it is about half of that. But I am not sure if this assumption is good for all cases of LID. The value is certainly between (1-0.4/2) = 0.8% LID if it occurs during the first few hours, or 0.3% if you interpret the first year degradation value as a linearly increasing function without any further assumption. I would tendentially use the more conservative estimate of 0.8% LID.

Hi, which version of PVsyst are you on ? This might be corrected by updating.

No, there is a problem with the components BeamInc, CircInc, etc. That's why the sum does not work. GlobInc is unaffected.

No, this is correct I think. Since this is GlobInc, not affected by the bug.

Hi, indeed, we have noticed this issue. We will be fixing this in one of the upcoming patches. Thank you for the feedback !!

Hi, this is likely because of the diffuse shading losses calculation. In version 7.4.8, you can check the details from the 3D scene window > Tools > Trackers diffuse shadings definition. If it is automatic, there is a chance that by ungrouping, PVsyst picked a representative tracker for the calculation (see the “central tracker” choice), which is not really representative. (2% losses is more realistic !) See https://www.pvsyst.com/help-pvsyst7/tracking_diffuse.htm or https://www.pvsyst.com/help/project-design/shadings/calculation-and-model/diffuse-losses-with-tracking-systems.html for the v8 help.

Only the intermediate results are incorrect (...Trp, BeamInc and CircInc), the other results including the final production are correct already.