Home battery storage market expected to boom in 2016., page-22

Economies of scale. The actual raw materials of the ZBM are not that expensive and once sales begin to happen the price will drop accordingly.

If I was an average person with an average house I would stay on the grid until the whole thing is economically feasable and proven, but there are a lot of people for environmental reasons or to be independent or want to go with modern technology that will do it because that is what they want to do and they have enough money to do it and they will get the ball rolling.