Recent threads started discussing the Tesla batteries. It forked into consumer and utility applications. Here is news of a 50 MW. 300 MWh battery to be installed with a solar installation in Japan. I cite this as evidence that large scale battery storage is on the cusp of acceptance. the article gives interesting details about the rationale. "The government is financing both projects at a total cost of ¥31.7 billion ($257 million), a government official said. Power companies have cited the volatility of supply as a reason for refusing to accept new solar power suppliers, effectively putting a brake on efforts to increase use of this renewable power in Japan. Part of the problem lies in the relatively small size of Japan’s power grids, due to the geography of the archipelago and the lack of compatibility between regional power utility grids. In Europe, where renewable energy is widely adopted, power grids are connected across the continent enabling surges in electricity generation in one location to be sent elsewhere relatively easily. During a boom in solar power investment in the two years after Japan’s renewable energy law took effect in July 2012, the southern island of Kyushu saw an especially large number of solar projects due to its relatively high levels of sunshine. Kyushu Electric suspended making contracts with new projects last September, citing problems with its grid capacity. The utility will use the new battery system to study how to stabilize electricity flows when solar power generates a large amount of power on a low demand day, a company spokesman said. Tohoku also enjoyed a solar investment boom because of its large areas of unused land. Tohoku Electric’s research into improved handling of solar electricity will start in February" An inexplicable part of the technical description of the battery says that it is 100m x 140 m in size. WTF?