Quick question, is there any way to make a system or something so if I have a factory building full of accumulators, when the power network is above a certain threshold, it charges them (power enters the building), but if it's below that threshold, it inverts the flow of power and starts draining the accumulators (out of the building)?

No, that's not possible, electric accumulators need to be placed outside next to your solar panels. Steam accumulators are possible inside factory buildings though.