Part of the advancement in fuel cell is our ability to produce hydrogen at a low cost.
That’s the only part, in fact, that needs advancement. And it’s in no way mirroring PV cells development path or cost decreases. Our most efficient, lowest cost form of abundant hydrogen is cracking it out of methane / natural gas. And that method will always be more expensive than just generating electricity from the methane because you need to generate high temperature steam as part of the process by burning some of the methane. The only other source of less expensive but not abundant enough hydrogen is as an industrial process byproduct. And that’s not even close to producing enough to meet current demands if we could magically capture it and had no refining costs to scrub out other wastes.