In addition, Tesla has released the warranty document for the DC coupled Powerwall 2. It’s a very good bet the warranty for the AC coupled version will be identical, and it allows us to determine the cost per warrantied kilowatt-hour.
And it is good.
The SolarQuotes Battery Comparison table gives the cost per warrantied kilowatt-hour for over 30 battery systems when fully cycled once per day. The results are shown in the graph below, and as you can see, both versions of the Powerwall 2 are well ahead of the closest competition.
The Powerwall 2 is almost 30% cheaper than its next closest competitor, but the comparison is actually better than the graph makes it appear because the AC version of the Powerwall 2 includes a built in battery-inverter and the DC version includes a built in DC converter while its closest competitors on cost per stored kilowatt-hour do not.
This means the AC Powerwall 2 could installed without any additional hardware while the next 4 battery systems on the graph would require a separate battery-inverter to be installed the same way.
But the 7th system from the left, the Enphase AC Battery, does include its own battery-inverter and can be used with any rooftop solar system, just as the AC version of the Powerwall 2 can.
While the Powerwall 2 is still not cheap enough for the large majority of people to save money by installing one, it is possible that some large users of electricity with 5 kilowatts or more of rooftop solar will be able to save money by installing one, so the introduction of the Powerwall 2 marks the point where the economics of on-grid energy storage starts to favour households rather than just the people selling batteries.
See also: Tesla price shock: Solar and battery storage as cheap as grid power and Solar and battery storage beat best gird offers by one quarter in South Australia
Finn Peacock is Founder & CEO at SolarQuotes
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