This is just one deal in a very large state, and Tesla may have a fight ahead as it competes with energy storage rivals like Bloom Energy. Even so, it suggests that Elon Musk and crew could play a significant role in modernizing California's power grid and hastening the state's shift to clean energy sources. If buildings can already store the energy they don't use and feed some of it back to the grid, it's that much easier for building owners and utilities to switch to green tech that makes better use of batteries.