Redox flow batteries are a vastly better option
Fuel cells do NOT act like batteries. At best, they work just like generators, but with potentially double the efficiency due to operating at much higher temperatures, though that usually doesn't work out as common hydrocarbon fuels can't be used directly, and the conversion costs energy. There's lots of data on them, and they've been in operation in special applications for decades, so I don't see what this "test" is going to turn-up. If they wanted to invest in R&D, that might help.
You know what acts like a battery? Batteries. And redox flow batteries* in particular can offer most of the advantages of both batteries (very high efficiency and easily rechargeable), and generators (unlimited runtime, storage in simple tanks, and possible to ship-in more as needed). It's obvious the future of backup electrical power is redox flow batteries, NOT fuel cells as they are only a tiny step forward.
* https://en.wikipedia.org/wiki/Flow_battery