You really do need to make distributed/decentralized generation the first priority for energy with storage the second. Make it a box that generates 1kWh/day that costs $99.00, something cheap and small.
Without generation and capture, there's nothing to sell or share. Capture could be thermal, compressed air or water potential, anything that doesn't rely on batteries should be considered. If you're just storing the energy as heat, imagine something as crazy as a molten-salt or phase-changed material carrier that you can carry back to your stove to cook on.
