You might have solar panels on your home. You might not. You're probably going to want a Tesla Powerwall Home Battery anyway. Capable of connecting to both residential solar systems and the traditional power grid, this rechargeable lithium-ion battery can store excess solar power for use when the sun isn't shining, store power from the grid when energy is the cheapest and put it to use during times when it's most in demand (and thus more expensive), and serve as a massive backup battery when the grid goes down. It's available in 10kWh and 7kWh varieties, and is just six inches thick and three feet across, making it easy to fit on the wall. And with a 10-year warranty, this is one battery that won't need replacing anytime soon.