I love the design, but I wonder about the "selling feature".
How many people regularly experience power outages (ok, if you're American relying on Canadian electricity, you might have a right to be concerned).
I'm surprised you're not touting the "save on your power bill" benefits. Could this not store power when rates are low, and use the battery when rates are higher, while maintaining a balanced minimum storage amount to ensure power is available should the power go out?
I'd think it could be quite smart about this if you looked at weather patterns and other factors to calculate a likelihood of an outage, and ensured more back-up was available.
From a selling stand-point, isn't saving money every day a better feature than "just in case the electricity goes out"?