Declining costs for solar photovoltaics (PV) and excitement about new technologies have led to speculation that self-sufficient PV/battery storage systems will soon become competitive with traditional electricity service. We compare a grid-tied residential solar system with an off-grid solar-plus-battery system at 1020 US locations, and calculate three effects of "grid defection" for each: the private net costs to the homeowner, the change in system generation costs, and change in system emissions. For the average US location, an off-grid solar system is almost double the price of grid-connected solar, is associated with higher system generation costs, and has no emissions benefit. (C) 2017 Elsevier Ltd. All rights reserved.