This seems to be the place to discuss the Tesla Powerwall, which did in fact go into production early this year, has been shipping since Mid-January 2016 using Panasonic batteries, and produced in Fremont CA near the Tesla automobile factory. Note that the early production units were all of the smaller residential unit, earlier described as the "7 kwh" model. The "10 kwh" residential unit did not ship and was later cancelled. The "100 kwh Powerpack" commercial version has yet to ship.
Tesla appears to be producing these units at a loss at the present time, and using Panasonic batteries exclusively. Plans for revised products are already announced from the Gigafactory in 2nd half of 2016.
In April, 12 months after the product announcement, unflattering reviews of the Powerwall Version 1 were published:
What's more, a detailed reading of the Powerwall manufacturer’s warranty reveals that Tesla guarantees a lot less storage than originally advertised for its 7-kilowatt-hour daily cycling battery system.
Specifically, the warranty covers 740 cycles or 85 percent of 6.4 kilowatt-hours (so 5.4 kilowatt-hours) of capacity for the first two years -- whichever comes first. Then it covers 4.6 kilowatt-hours for three years or 1,087 cycles. And finally, it covers 3.8 kilowatt-hours for five years or 2,368 cycles.
Based on these figures, SolarQuotes estimated that each kilowatt-hour delivered from a Powerwall would end up costing an average of AUD$0.50 (US$0.39), making it more expensive than the residential storage offerings from Aquion, Redflow and Sunverge.
The calculations do not include the cost of an inverter, which would push the upfront bill to AUD$12,000 ($9,265) and the per-kilowatt-hour cost to AUD$0.75 ($0.58).
Rest of article: http://www.greentechmedia.com/articles/read/is-teslas-powerwall-luster-already-fading
There were also detailed analysis of payback periods, using the installed cost of entire solar PV systems, including installations in Australia, Germany, and the USA:http://www.forbes.com/sites/christopherhelman/2015/05/01/why-teslas-powerwall-is-just-another-toy-for-rich-green-people/#1730a2854879http://instituteforenergyresearch.org/analysis/payback-on-teslas-powerwall-battery/https://web.archive.org/web/20160108035235/http:/www.engadget.com/2016/01/07/study-a-tesla-powerwall-pays-for-itself-after-nearly-40-years/
Tesla got the above article changed, this is the current version:http://www.engadget.com/2016/01/07/study-a-tesla-powerwall-pays-for-itself-after-nearly-40-years/http://instituteforenergyresearch.org/analysis/tesla-fails-to-refute-iers-powerwall-article
Bottom Line: Although it makes sense when your house is off-the-grid, Powerwall is not an economical solution. For example, I produce power from my grid-tied rooftop solar PV at USD$0.31/kwh, using some pricey 6-year-old PV panels. But with today's cheaper PV and Powerwall, the price goes to USD$0.59/kwh. (Which analysis does not include the probability of replacing the Powerwall twice during the assumed 30-year life of the PV panels and inverters.) (You could choose to believe that Tesla can make 30-year batteries, but I would not, the warranty is 10 years.)