Ok, lemme see if I can explain this correctly... Using the power plant building I set up a single nested power plant. Both buildings are power plant buildings. The first building (placed in normal game world) takes in water and coal from outside, has burners inside it and the hot water feeds another power plant building inside that contains the steam engines. Here's my problem / bug: if you place accumulators in the power plant building, they fit with your power only flows one way restriction. Power from the steam engines inside the building fill the accumulators, and the accumulators only need to feed power out of the building when draw demands it. The factory power receiver wont draw power from the accumulators though so no power can actually leave the building from them, only from the steam engines. I would expect the accumulators to feed power out.

Accumulators don't work in power plant buildings, since the energy acceptor is an accumulator too and accumulators don't share energy. It is intentional that the energy acceptor is an accumulator, because otherwise the machines inside a power plant building would not receive priority power.

Accumulators inside power plants will only be used as backup power for the machines inside, in case power production stops for any reason. If you want to use accumulators for energy buffers, you need to place them outside your power plants.

Design decision then. That's fine. Thanks for the quick reply. :)

Awesome mod, btw.

So there is no chance of being able to fill factories with accumulators?