Hmmm tricky to get it super accurate, how far away is the camera going to be viewing these panels? This is what I came up with after 20 minutes of messing around. Basically Corona scattered loops with some deforms on the ring like structures, and it renders quickly. Let me know if you would like the scene
If you can get a photo of the foam from a head on view, you could try and make a displacement map, then use the water level amount to cut out the back. Like in this example… this was done with the provoronoi from siger.
Does the light need to pass through it - or will it be cladding on top of an opaque surface?
If it’s the latter and you’re not super close then you may be able to get away with using a cellular map piped into diffuse, reflection, gloss and bump to create a plausible effect. I did something similar once - same kind of structure but it was made out of metal.
edit I had forgotten that I had the light passing through it too. That was probably a displacement with a cutout in that area. Attached are two crops. Texture was scaled up so it could read better as the camera was on the opposite side of the street.