The Tesla Powerwall Home Battery not only looks good, but it works great, too. It can be connected to both residential solar systems as well as the traditional power grid. Being a rechargeable lithium-ion battery, it as the ability to stash excess solar power so that you can use it whenever the sun is hiding behind some really thick clouds, or to stash power from the grid whenever energy happens to be at the cheapest. Heck, its value is further enhanced when you use it under the highest level of demand, where you can choose from 10kWh and 7kWh varieties.
The entire shebang measures half a dozen inches thick and three feet across, which is easy for it to fit on the wall. Apart from that, there is also a 10-year warranty, making this one battery that should last you for quite a while before a replacement is required. Could this be the “Missing Piece” after all?