Tracking PV Planes Misalign

[ThomasP]

I'm using PVsyst V6.62. The system is a single axis tracking system with backtracking. I'm using tilted axis tracking planes with multiple rows. I want to use misalign so that the trackers follow the angle of the plot boundaries. Only a negative pitch ( -6 m) gives the correct tracker misalignment that matches the plot boundary (PVsyst does not seem to allow a negative misalign value to be used in order to change the direction of misalignment). Specifying a negative pitch however leads to the following error"...the pitch between trackers is too low" and hence the shading factor tables can't be calculated for this system. How can I specify tracker misalignment in the opposite direction of the default misalignment direction?

[André Mermoud]

I don't understand what you are doing.

A negative pitch doesn't make sense in the calculations. It is so unusual that we even not thought to forbid it in our error messages.

By the way, you cannot use the backtracking strategy with a misalignment of the trackers.

See the FAQ How is defined the Tracking Axis azimuth ?

[dtarin]

I think he meant that we would like to misalign the modules to the eastern direction. Entering a positive value for misalign points them to the west. Entering a negative value for misalign points them east, but this it not allowed. I also would like to misalign to the eastern direction, but do not know how (or if it is possible) to do so.

[dtarin]

I don't understand what you are doing.

By the way, you cannot use the backtracking strategy with a misalignment of the trackers.

See the FAQ How is defined the Tracking Axis azimuth ?

 

Andre,

Backtracking with misalignment isn't forbidden in PVsyst. Are you saying that if it is selected, the results are not accurate?

[JFHC_85]

Hello everyone:

In one of my PV Plants Project I have the same issue about misalignment of trackers. As Solarguru said, backtracking with misalign is allowed in PVsyst, however the eastern misalign is not. My question is: Since you cannot put a negative pitch in the 3d scene, is it right to run a simulation without misalignment? Will be near shading losses too affected with this difference?

Thanks in advance.

[Darcy_CTP]

It sounds like this is a bug in PVsyst that should be rectified. It seems strange that a negative pitch can be specified but a negative misalignment cannot. Is there any accurate way for a misalignment in the eastern direction to be input?

[jforbess]

I also have this problem. I would like to misalign my tilted tracker so that each row is more northern to the east, and it seems incorrect that the way to accomplish this is with a negative pitch, and a positive misalign value.

[samastor]

Good evening

Of course i am dealing with the same problem, since misalignment can only be possible for tracking planes towards the West. I attach two shading scene examples. The East scene can be computed correctly. On the contrary the graphical result for the West scene can only be obtain using the negative pitch value thus computing is not available. Is there any solution to this with the current version? If not with the current version is it expected to be solved with the next one?

[unilhexio]

Would be wondouful if someone from PVsyst does any comment about this...

[coenrw]

I would recommend you stop trying to make this work if you are using version 6.68 or earlier. PVsyst simply won't allow you to misalign trackers to the south, east to west, if you're using backtracking.

Background:

The Misalign setting only allows the input of positive values. This means misalignment to the south, from east to west is not possible with this setting.

The Pitch setting allows negative values, so theoretically you can misalign to the north, west to east, to achieve the same result, but when you create your shading scene this way, you get a message saying the pitch value is too small and you cannot proceed.

So, then, you would think you just have to create each tracker row separately and place it accordingly in your scene, but if you do that, when you complete your scene you get a message informing you that the backtracking function only works when there are multiple rows defined in your creation of the "Tracking field". That is, backtracking doesn't work for individual rows placed next to one another. It only works when you define multiple trackers in the Create > Tracking PV planes window.

[unilhexio]

I would recommend you stop trying to make this work if you are using version 6.68 or earlier. PVsyst simply won't allow you to misalign trackers to the south, east to west, if you're using backtracking.

 

This is a new software limitation. I can remember how I did it in former PVsyst versions (see http://forum.pvsyst.com/viewtopic.php?f=24&t=2349).

[samastor]

I would recommend you stop trying to make this work if you are using version 6.68 or earlier. PVsyst simply won't allow you to misalign trackers to the south, east to west, if you're using backtracking.

 

But this is a problem of the software as real fields can't be restrained to accept "only" what the software accepts. There are numerous projects where we have installations with such layout thus impossible to obtain a relevant information related with the expected energy yield to perform analysis of data etc. One thing is what the software permits to allocate and the other thing is reality. And since reality is what should drive development that is the reason we keep asking for a solution or if there is any alternative idea.

In PVsyst 5.74 for example it is stated clearly that for the tilted axis tracker:

Tilted axis: the Phi angle around the axis is adjusted for no shadings conditions. This doesn't allow for misaligned arrays.

(Under Help/Near Shading/Backtracking strategy)

Same is also said in the PVsyst 6.68 help BUT when you make a misaligned tracking plane system has no problem calculating the shadowing using backtracking option (providing a table of linear shadowing with a factor of 1 at all inclinations). So there has been development on this approach hence it is only applicable one way. Therefore any reply from someone from PVsyst development team would be highly appreciated.

Thanks,

[Sylvain Pepoli]

Hello all,

PVsyst will allow negative N-S pitch for horizontal/tilted axis trackers in the next version.