This post on the WierdTechNewsHub mentions the GridPoint Protect. This is a device that connects to the main circuit breaker and stores electricity when rates are low, and then it supplements utility power when rates are high. This will also work as a backup during blackouts.
Supposedly, this will save 10%-15% off your electric bill. The version of the GridPoint Protect that is meant for home installation is $10,000, so it might take a while to recoup the initial cost.