The iron-core transformer is the 140-year old technology that props up both the electrical grid and AI companies. The devices are clunky but reliable, which explains why they’re still in use: if it ain’t broke, don’t fix it. Yet as the data center power demand skyrockets and batteries and renewables carve out larger portions of the grid, the ancient technology might finally be hitting its limit. Fortunately, their electronic replacement — the solid state transformer — could be having its moment,