Q: If power from the utility is cut (storm, trees, down lines), the utility will NOT accept power from your panels.  To survive an outage a battery or generator will then be needed; savings and eco-impact are then significantly different.

A: By law, solar panels must disconnect from the grid during a grid outage. This prevents the linemen from getting electrocuted by your solar electricity. If you have a battery you can, during a grid outage, reconnect that battery and the solar panels to your house “behind the meter” (meaning still disconnected from the grid). This is what I am currently installing at three properties. Now the battery and solar panels are acting like a back up generator.