Couldn't Tesla take care of that? For the right price of course.
In other news: I found this image in the comment section of an article on Tesla (has it been posted on here before?). It cements in my mind Tesla's ambition with regards to batteries (which I think most investors still can't really fully understand)
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What is really interesting in my mind with this graphic is the cost of the inverter. In solar systems, the cost of the inverter is a large portion of the system price. In a P85, the inverter is capable of 310 kW. The entire drive unit, motor + differential + inverter is reported to cost somewhere around $15,000. I'm not sure if labor for the swap out is included. Assuming the motor + differential is 1/2 that cost, we are looking at $7,500 for the inverter. For such a large component of the Model S, I assume that the GM that Tesla gets for the Model S roughly translates to this part also.
To compare, a Sunny Boy 11000TL-US which converts DC from solar panels to AC 240v at a peak of 11.5kW costs just over $3,000. SolarEdge SE10k-US is just under $2,000 for 10kW (480v 3phase). In comparison, on a linear per kW rate, the Tesla inverter would cost about $275 for 10kW. I'm not sure why such a large discrepancy in pricing. One would assume that everyone can buy IGBT's at volume price and put out inverters at a very low price. Maybe the floor pricing is high and the incremental price for higher power isn't very much? If that were the case, there shouldn't be the spread in pricing between lower and higher priced inverters:
http://www.wholesalesolar.com/inverters.html
Looking at the batteries alone, Tesla currently charges $280/kWh for the 60 kWh to 85 kWh battery upgrade in a Model S. A 30 kWh battery pack would cost somewhere around $9,000 (have to add some for the battery enclosure). Add an 240v 20kW inverter for $1,000 and a DoD of 75%, we're looking at $10,000 for 30kWh capacity, 22.5kWh usable solar storage unit, or $0.44/watt. I would expect that at 75% DoD, this setup would have > 3,000 cycles of life to 80% usable capacity.
For comparison (not picking on them, they just have handy kits with prices attached), off grid solar pricing looks like this right now:
http://www.wholesalesolar.com/solarpowersystems/workshop-8-off-grid-solar-power-system.html
The Rolls battery bank there is 61.6 kWh for $8,674. Remember, for these kind of lead acid batteries, depth of discharge is recommended at 50% to get even close to 2,000 cycles. To get to 3,000 cycles, we're looking at far less, let's guess 40% DoD, which brings us to the same ball park as the Tesla solution above. Presumably, the $280/kWh figure that Tesla is charging has a significant GM... approaching 30%. Which means Tesla's 2012 pricing and battery solution is already price competitive on a total lifecycle basis as lead acid batteries designed for off-grid solar. As we go forward into the era of Gigafactory battery pricing, the difference will be significant.
However, the big price difference is in the power electronics. That pricing is roughly $15k in the off-grid solution above. Plus, the capability of discharging at 2C (120kW on a 60kWh battery pack) at a relatively decent price point, say $3,000 means that the battery pack and inverter system can be sized to carry the load of most houses - including the big loads like emergency resistive heating and hot water heaters.