My concern is with the use of Lithium-Ion batteries. Lithium is already a hot commodity with the high demand for all of the rechargeable batteries in our electronic devices. Another issue is the production of Lithium produces toxic waste materials that must be dealt with. While it certainly looks good on paper, I wonder if having people unplug from the electric utilities will put our infrastructure in jeopardy. Less people requiring less energy from the electric companies means less money available to maintain the existing infrastructure.
I have always been a proponent of utility scale solar chimney power plants. Sure, they aren't revolutionary, nor are they a product that can be sold to consumers individually, but producing electricity with almost no environmental impact surely seems the best option for utilizing the vast amount of solar radiation that reaches the earth on a daily basis. The operation of the plants produces no waste products as they operate on simple thermodynamics. They can be scaled and adapted to run 24 hours a day.
The biggest hurdles are the cost of the initial construction and the large footprint they require to be effective. I personally believe these are not true hurdles, but mere bumps in the road towards energy sustainability.