Sensor grids for Sunlight beam index

I try to compute the Sunlight beam index (SBI). This is an aparture based metric in [m2hrs] by developed Mardaljevic ( It contains a cross sectional area of a beam sunlight entering a space.

In this example I would like to compute an annual SBI with a timestep of 15 minutes. To test I try to compute it for 2 hours between 12h and 14h. Because of the cosine effect the view should for each sun position rotated to get the right area of normal illumance on the grid.
The aperture is exactly south orientated.

How do I get the right position and how can I change automaticly rotate the sensor grid plane for each sunposition?

Any suggestions are very welcome! Thanks. (97.0 KB)
SBI.3dm (67.4 KB)

Hey @Jurrijn ,

I’m not really sure how your question relates to your Grasshopper file since your grasshopper file just has a view-based study and a direct sun hours study. You can always set the direction of the sensors in your sensor grid to be equal to a sun vector created with the LB Sunpath if you need sensors that are facing perpendicular to the sun.