> What happens when that much energy is so cheap and every home has what amounts to a sizable bomb inside? There is very little correlation between the amount

> What happens when that much energy is so cheap and every home has what amounts to a sizable bomb inside? There is very little correlation between the amount of energy contained in a device, and its likelihood of exploding. A container of helium does - after all - contain an enormous amount of potential energy (if fused), but that's not gonna happen all on its own. Your worry about batteries exploding, is because of your experience seeing Li-ion batteries exploding (or at least burning very quickly) in videos. But this is something specific to the Li-ion battery chemistries. It has very little to do with the energy stored in the battery. It's the flammable liquid electrolyte catching fire that's the primary cause. Solid state chemistries contain even more energy, and do not explode at all. You can cut them in two and nothing happens. Their problem is cycle life though, but that might be solved. A home battery pack will be built in a much more safe manner than a cell phone battery, they have more space to go on and they're experience less physical stress than a cell phone or even a car. One of these spontaneously catching fire is likely to be a freak accident, possible but extremely rare. And it's likely to be a fire, not an explosion, as the cells will be more contained than in a cell phone. Check out the video of Tesla setting one of their grid storage battery packs on fire. It's not very spectacular.