Splitting PV surfaces gives a different result

I made an PV surface simulation with the Ladybug tools including the Ladybug_sunpath Shading component.
In the first simulation I used simple surfaces which cover most of the roof.
In the second simulation I splitted these surfaces into smaller parts so I could get a better view of how much energy on which spot is generated. Unfortunately the results of both simulations differ quite a lot. I used for both simulations the same parameters. (the energy per year is written in white)

undevided surface

devided surface.

What could be the issue here?
(I used the standard template: 020_Photovoltaics shaded analysis)

@Erikbeeren Can you please share a sample file to test?
cc @djordje

Hi @devang, @djordje

Thanks for your answer.
Hereby I send your my sample file.

solar_panels.gh (666.0 KB)

Thank you for the tag Devang.
Erik is it possible to only leave the divided and undivided surfaces in the file and photovoltaics components in the .gh file?
When I open solar_panels.gh, I get a request to install 3 grasshopper plugins, which I do not have.

Hi @djordje,

Sorry, I thought I cleaned it up. :frowning:
I hope you can open it now.
solar_panels.gh (675.4 KB)

Hi @Erikbeeren,

There is 4% more area of the divided than large PVsurfaces, but this is not the main reason for the larger output of the divided ones.

The main reason is shading.
What “Sunpath shading” component does is - it picks the corner points of the PVsurface, calculates the “annualShading” for each one of them - and then averages them. This is the annualShading for a single PVsurface.
When your PVsurface is 28 meters long (like one of them is), getting annualShading from its 4 corners can give quite vague values. In this case overestimated.
This is why, whenever you can, you should divide the PVsurface into some reasonable panels. This can be for example the width/height of a standard residential or commercial PV panel - approximately 1x2meters let’s say. Your divided PVsurfaces are some 1.8 meters wide, which is sufficient measure. I wouldn’t divide it the other direction.


Hi @djordje,
I actually noticed that deviding the surface in smaller PVsurfaces (1m2) made the simulation crash.
So thank you for the clear information. I will take it into account with future simulations.

Hi Erik,
How does the crashing look like?
Rhino crashes or the “PVsurface” component crashes (you get this red marker)?

Hi @djordje,

After more then 20 minutes trying to solve, the component stops with the orange exclamation mark in front of it. To much data I suppose.

It would help if you could share the exact error message and the picture of the message so it is clear from which component the error is coming from.

I agree with Devang.

All Ladybug Renewable components (Gismo as well) are created on Intel E4300 1.8GHz, 2GB RAM and Windows XP and I still haven’t experienced crashes when running them.
There were times where I leave the Grasshopper to calculate something over night, and in the morning the results are there without any crash. At least this was the case on Rhino 5. I am wondering if it was more stable than Rhino 6?

If you get crashes, try all of these fixes:

  • Restart PC before running the .gh file.

  • Remove all (yellow) Panels from component outputs, except the final panel.

  • Open all Ladybug Renewables components and comment-out (add # in front of it) the “printOutput” function at its very end:

  • turn off the geometric preview on all components by selecting them, middle mouse click - “Turn off preview”.

Hi @djordje,

I shall run it once again and send you the outcome.

With kind regards,

Erik Beeren

Hi @djordje and @devang,

This was the error I got.
Sometimes it appears when running a lot of pannels in one time and the viewport in Rhino is set to rendered. It helps when I set the viewport to Shaded. Thanks for your help!

Hi @Erikbeeren,
I didn’t know about this about the rendered-shaded view.
Then try to set the view at Wireframe, at least during the calculation is running.

Also try the 4 steps from my previous reply. If it is too bothersome to do the step number 3), then you can apply step 3) only to “Photovoltaics Surface” component.