Can you please add this option to energy storage units so it will be possible to make following scheme: place many MFSU's closly and connect them to one carrier redstone signal, and when last of them is full - output signal is off and we do not need more energy to produce (in case of carrier connected to nuclear reactor for example). Without this you need to combine these signals (from MFSU's) using AND gates and you need a lot of free space for it.