Almost entirely depends on how much it costs to deal with the ground having night, and if this is more or less than the cost of putting it somewhere that doesn'

Almost entirely depends on how much it costs to deal with the ground having night, and if this is more or less than the cost of putting it somewhere that doesn't have night. Both are already things that can be done in principle, the question is just how expensive the solutions are. For scale: if these million satellites were 25kW each, that's 25 GW total; Tesla supplies about 150 GWh of batteries each year between cars and PowerWall units, so provided they didn't need replacing more than every four years this would be enough to supply a data centre that size for 24 hours, so you'd just need to put this all somewhere without much cloud cover.