I believe they are in early stages of transitioning from...

I believe they are in early stages of transitioning from development to commercialisation. Same issues with expensive new technology, it needs manufacturing of large orders (including subsidies) to help bring down the unit price. Umm, much like err who can I think off?

In the end battery storage like flow batteries will be in the mix for storage and fast despatchable power, while fuel cells will be there to provide sustained and rampable (at a slower rate) power generation.

Anyway, best you move yourself to the RFX BB if you want to follow what's happening there.