I currently have a 100 volt system (thirty LiFePO4 cells) and its been operating for enough years to keep me in the original less than 120 volt category.
So what I "could" do is ground the centre point of my battery so its +/- 50v dc.
It would need some interesting redesign of the home built solar controllers, but it would then effectively become two 50 volt systems.
Many homes in Australia, including my own, are supplied with two or three separate 240v phases.
Its still considered to be a 240v system, even though there is 415 volts between phases.
I don't see how two 50 volt dc systems are any different than that in the strict legal sense.
I am sure a silver tongued lawyer might successfully argue that distinction.