On its website, Tesla now says "each Powerwall has a 6.4 kWh energy storage capacity, sufficient to power most homes during the evening using electricity generated by solar panels during the day. Multiple batteries may be installed together for homes with greater energy needs." The larger model, on the other hand, was marketed as a "home backup" system that was only for weekly charging -- something most folks apparently don't need.

However, Tesla is likely also clearing the way for new Powerwall models that could arrive this summer, as it recently hinted at a private gathering. If that proves accurate, you can probably expect more daily charging Powerwall models with even higher capacity and durability.