"Never. By a long shot." At least in terms of financial outcomes. If it improves reliability, it's common enough, but a solar + battery system does well to c

"Never. By a long shot." At least in terms of financial outcomes. If it improves reliability, it's common enough, but a solar + battery system does well to come in at 4-5x grid rates, even in expensive areas. My office system (off-grid solar + battery) has now dropped below $1/kWh delivered... but not by much. And the batteries are more than halfway through their expected service life (10 years, flooded lead acid). I do it because it's interesting to learn and experiment with, and because trenching power out here would suck, but I don't pretend it's cheap. On the other hand, it is more reliable than the power grid...