The energy beams don't seem to work properly with Thermal Expansion's Energy cells, and I think it's because the sides are configurable, while with Galacticraft machines there are specific in-sides and out-sides. When I place a beam receiver on an energy cell it is always green, which seems to be the "receiving" mode, even if the energy cell's side is set to output energy. The same thing also happens with the Tardis mod's energy circuits, which can also send/receive.