@ 98% uptime, that's not good enough for a tier 1 datacenter. In fact, it appears that Google used Bloom Box to power parts of their Mountain View Ca campus, not their data center.
Now if you took an array of elements @ 98% reliability, at some number of elements you could achieve 100%. The issue is that most of the time you'd produce far more that you needed. Makes sense to want to sell the variable excess.