Isn't this already done for accumulators?
When they are placed or changed, they are separate until their energy level syncs up with the rest of the accumulators, and are then computed as a single entity.
Yes, but the difference is, that they can be used together, without any change in behaviour. Consumption machines can use different levels of energy based on activity (one fully beaconed assembler uses way more than assembler full of efficiency modules for example). So the problem with entities is little bit more complex, but solvable.