Some things to think about - the cells will respond to light from the sun and also light reflected from the earth - not sure if you need to consider that. Solar energy isn't constant though the variation might not be enough to consider in your design. The angle of the solar panel with respect to the sun and earth will impact the amount of energy each cell generates. I'd guess that the maximum a cell could generate would be in the strongest sunlight with solar output at peak - the minimum being almost nothing if you are on the dark side of the earth. It would seem that each cell could be either of the extremes and anything in between.
Your control should probably look at output capability of each cell as well as be aware of the battery condition - and direct the power where and if needed. I'd start by making a block diagram of what you have then start thinking about how to ascertain cell output capability, battery level and don't forget the optimum charging conditions for the battery. Rotation of the satellite might be a concern if it rotates fast enough.