They seem to think it is more useful as a backup, but I'm inclined to say (especially in part because we actually don't get a lot of outages in our area) that the more useful reason would be to minimize how much electricity you buy from/sell to RMP. Are we talking about saving pennies here, or is that savings fairly substantial? I know RMP is not great with their net-metering policies and they don't give you much for energy buy-back.