The Silver Capacity of a celestial body refers to the absolute maximum amount of silver that can be held at any one time. This differs from the way Energy Capacity works - where you can overfill on your energy capacity. Any silver over this limit will disappear completely if it lands on a celestial body which doesn't have space.
The Silver Capacity of a planet is shown next to a "ZK Banknote" image in the information pane. Unfortunately, this celestial body is broke :(
The Silver Capacity of planets also gives an indication as to how much each upgrade will cost, the first upgrade costing 20% of the maximum capacity, the second 40%, and so on, up until the final upgrade.
The silver capacity is dependent on only three factors:
In some rounds (namely, DFDAO’s Arena), the Silver Capacity multiplier may be set to different values. A change in this value will also change the upgrade costs for planets, to match the aforementioned 20/40/60/80/100% cost structure.
For more advanced players, you may wish to take a look at the exact values of a round by using the following in the console: