This is a 28.2GW super power station, which I built just for fun, as I can't really imagine what scale of factory would require so much electricity.
It is stackable, with each module having a capacity of 4.9GW. The modules on both sides lack 6 adjacent bonuses each, resulting in a total capacity of 4.9x6 - 0.6x2 = 28.2GW. To compensate for the 6 adjacent bonuses that the fusion reactors at both ends are each missing, you can place three fusion reactors at one end, as shown in the picture, to achieve 29.4GW.
Similarly, higher capacities can be achieved by joining more modules. One single module has a capacity of 4.9GW for 9 fusion reactors, which I think should be the most efficient method currently.