MIT engineers created a carbon-cement supercapacitor that can store large amounts of energy. Made of just cement, water, and carbon black, the device could form the basis for inexpensive systems that store intermittently renewable energy, such as solar or wind energy.
Or you could make the pad thicker for the purpose of storing more power. Or just make some concrete in the driveway, as blocks stored underground and out of the way, or as part of the walls instead of limiting it to only the foundation.
All of which are great for double duty uses even if additional options are needed because it reduces the space needed for additional options.