For years, low-cost solar-plus-battery systems were seen as a distant possibility at best, a fringe technology not likely to be a threat to mainstream electricity delivery any time soon. By far, the limiting factor has been battery costs. But thanks to a confluence of factors playing out across the energy industry, the reality is that affordable battery storage is coming much sooner than most people realize. That approaching day of cheaper battery storage, when combined with solar PV, has the potential to fundamentally alter the electricity landscape.