A long time ago, back in the days before we knew how lame the original Powerwall was compared to its hype or how good the Powerwall 2’s hype is compared to the original Powerwall, I wrote about whether or not my parents in sub-tropical Queensland could save money by going off-grid using lead-acid battery storage.

My conclusion was they could not save money even under almost ideal circumstances.  The benefit of staying on-grid and receiving even a low feed-in tariff for surplus solar electricity was too great to make saying sayonara to the grid connection wire worthwhile.

But now Tesla says the Powerwall 2 will will be available in February and they have given its technical specifications, warranty, and price. This has allowed us to determine its warranted cost per kilowatt-hour is 30% less than its nearest competitor and half the price per-kWh of the Powerwall 1.

The dramatic price cut means that, in some very specific situations, adding a Powerwall 2 to a grid connect solar system, may pay for itself. Just.