The response of the entrance filter, fused silica, mirror reflectivities and CCD quantum efficiency looks like this. (NOTE: the y-axis is now going to be some sort of quantum efficiency, not transmission. But the relative numbers are right. Everything does in fact die below 1600, and the rolloff at 1um is real -- that's where the CCD finally dies. I didn't see this until later and I've got too many other things to do right now to fix this.)
Now, fold that against some random solar spectrum to get this: