Solomani Navy: Mothballed Fleet distribution
So I counted up the mothballed ships in Sector Fleet, and came up with eighty battleships, eighty cruisers, and two hundred and four destroyers, though I did use the largest figures.
Given that a military district is about one and two thirds a sector, and the Spinward Marches only covers eleven subsectors, I'd double those figures, which means the Solomani should have one hundred and sixty battleships, one hundred and sixty cruisers and four hundred and eight destroyers in mothballs, per district, not counting how many they'd have in reserve at the strategic reserve.
The Solomani have just managed to secure a ceasefire in the face of (to them) an existential war, and going by the narrative detailing the expansion of the Third Imperium, you get the impression that the Solomani Sphere is mostly a backward region, industrially speaking.
Once the Solomani Sphere gained autonomy, it's also unlikely that the Imperium Navy handed over any of their warships, other than the very oldest that they had marked for disposal.
That means, the Solomani have had only two centuries to build up their Navy, most of it was likely destroyed a century ago.
Added to this is that the Confederation relies a lot more on member worlds building up their local naval assets, which means less allocation for the Solomani Navy.
So since you have about sixty four battleship equivalents against about eighty mothballed capital ships, that's slightly more than one to one ratio, per sector.
Going by Fighting Ships, the War of Imperial Aggression saw the Solomani Navy just having achieved tech level fourteen, possibly by one or two decades. That means that any battleship constructed at tech level fourteen would still seem relevant in today's fleet, the clincher being the bonded superdense hull. Crystaliron hulled ships would have to be relegated as second class at minimum, third class or mothballed otherwise.
Hard to believe that one hundred and thirty battleships and battlecruisers would manage to survive per equivalent military district as the Solomani agreed to a ceasefire, because if they had that available, you'd have a couple of more large space battles in and around Terra. That number is important, because from that stems the number of mothballed battleships.
Let's half that, and assume that over the past century, the Solomanis have managed to replace their tech level thirteen battleships with tech level fourteen dreadnoughts, those that aren't used in, and haven't been downgraded to, the cruiser role. The mothball fleet would therefore consist of refurbished tech level twelve capital ships.
Taking an extreme position, that most of the Solomani cruisers were wiped out during the war, and the Navy barely bothers to construct any, any that do exist are in use, haven't been mothballed, and their numbers are supplemented by reroled tech level thirteen battleships.
Destroyers seems a little vague, but the implication is that they are larger than two thousand tonnes, and their numbers probably got severely decimated a century ago, and considering their size, a candidate to be gifted to a member world to augment their navy.
So maybe sixty five battleships per district, that are continuously taken out of reserve and used as cruisers and training ships, no cruisers in mothballs, and maybe two hundred destroyers mothballed.