For a single satellite, we'd need a football sized array for heat dissipation. The dissipation capacity isn't equal across the entire array. And you need some way to move the heat from the centre out towards the edges.
And aside from that, 100k satellites is the limit of objects we can put into low earth orbit before we start risking cascade collisions that break everything into small bits and make getting anything into orbit impossible. We're currently at 14k objects. Space X is proposing ONE MILLION satellites. And they'll each need huge heat dissipation arrays.