I have been watching the correspondence about noise on the power buss with great interest. I am waiting to see if a noise specification comes out of this. I can tell you that the power buss will probably be noisy at least to your standards. The latest plan would have lot's of capacitance on the buss (many Farads) but of course that would not help with the high frequency noise. I have been noting the discussion about noise from the inductors and that will be taken into account in the design. In other words we will probably shield all the inductors as best we can and have  EMI shielded Power converters. The plan calls for a distributed system where there will be many small converters and not just one or two big ones. 

We plan to have many max power point converters mounted near the solar panels and then many cell voltage to buss converters located where the battery and super capacitors are placed. They are not planed to be synchronized so the frequencies will vary based on load.

In other words modules should build in as much noise immunity as possible.