Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Tesla Stationary Storage Investors Thread

This site may earn commission on affiliate links.
This is great news for investors. It provides a second market for Tesla if demand for Model 3 doesn't live up to expectations, or if the model 3 is late while the gigafactory is complete and running - this could buy them more time. So, from a risk management perspective this is huge.

Also, I would expect this to be a great talking point in negotiations with gigafactory suppliers in Japan.
 
Here are some of the slides from the JB Straubel Keynote in the OP. (From Greentech Media)
straubel1_400kWh_Building_Block.jpg

Straubel2_installation_factory_photo.jpg

straubel3_energy_storage_product_overview.jpg


Edit: In my opinion, the residential battery in the slides isn't that useful, unless it is a building block for a larger capacity system, but it would greatly depend on how it's used (and what utilities allow). The commercial batteries seem to me to be the money makers (savers?), and I expect most of their sales will be commercial.
 
Last edited:
Ok, Bearish question incoming: Why are LiIon batteries good for home storage? I thought LiIon's benefits were high physical density, which is ideal for a car. But for home storage where size and weight matter little, there are other technologies more optimal?
 
Ok, Bearish question incoming: Why are LiIon batteries good for home storage? I thought LiIon's benefits were high physical density, which is ideal for a car. But for home storage where size and weight matter little, there are other technologies more optimal?

Size and weight *do* matter. The "current" technology is a big load of lead-acid batteries in a basement.

They require maintenance and relatively high replacement rate.
 
One aspect of residential battery storage that could be useful (to model S owners anyway) is if they can use it as a personal on site supercharger. If the battery has sufficient capacity (wouldn't necessarily need to be as large as the model S battery) to do at least a 30 to 50% quick charge on a Model S via direct DC to DC connection, that could be useful.
 
Ok, Bearish question incoming: Why are LiIon batteries good for home storage? I thought LiIon's benefits were high physical density, which is ideal for a car. But for home storage where size and weight matter little, there are other technologies more optimal?
I think it all comes down to mass production. In Tesla's case they want to mass produce batteries that can also be used in cars. Also, in the home people do want small. They want something to hang on the wall in the garage like Tesla's current test product. Other technologies would be fridge-sized or bigger so while that works on the grid it really doesn't work in a home.
 
Ok, Bearish question incoming: Why are LiIon batteries good for home storage? I thought LiIon's benefits were high physical density, which is ideal for a car. But for home storage where size and weight matter little, there are other technologies more optimal?

wk057 talks a bit about space requirements in setting up a usable home battery using Model S cells/modules, and why lower density is not good enough Plan: Off grid solar with a Model S battery pack at the heart - Page 45
 
One aspect of residential battery storage that could be useful (to model S owners anyway) is if they can use it as a personal on site supercharger. If the battery has sufficient capacity (wouldn't necessarily need to be as large as the model S battery) to do at least a 30 to 50% quick charge on a Model S via direct DC to DC connection, that could be useful.
But the pilot project battery posted above only puts out 5kw. That is only equivalent to a 30 amp circuit. Maybe they made a big revision in the new announcement but it seems like they are not optimizing for high discharge rates.
 
One aspect of residential battery storage that could be useful (to model S owners anyway) is if they can use it as a personal on site supercharger. If the battery has sufficient capacity (wouldn't necessarily need to be as large as the model S battery) to do at least a 30 to 50% quick charge on a Model S via direct DC to DC connection, that could be useful.
Since a single residential unit has only 10kWh capacity, it can only add about 12 percentage points of charge to an 85kWh Model S. No supercharging with that!

The 10 kWh size seems a little light based on my cocktail-napkin analysis. If your daily solar matches your daily consumption, and your daily consumption is a typical 30 kWh (about average in the U.S., excluding EV usage), then you'll most likely max out your battery by early afternoon given the cooler AM temps and lower use of lights, cooking appliances, and entertainment systems in a typical household. 10 kWh does seem to be enough, though, to shift nearly all your grid electric use to midnight–6am, which is good for time-of-use rates.
 
I think the batteries will be stackable in units of 10kWh, so the storage can be sized to what the homeowner needs.

The batteries they are using are less energy dense, so presumably cheaper than vehicle packs. Maybe their cost is under $200/kWh? If they can sell 10 kWh packs for $2500, that is probably at least a 20% GM margin before the GF comes online. JB also talked about how some customers prefer a leasing model.

Elon has said it will be "plug and play" - is it possible that it could be as easy to set-up as plugging the battery into a NEMA 14-50? Or does it need to be connected to the grid by the utility? Especially in California, there has been a lot of trouble with utilities dragging their feet connecting the batteries, I wonder if they found a workaround for that?
 
For residential usage, if I am using net-metering for peak-hour demand, will stationary storage still help me save money? If the solution helps me go off grid completely, then yes, I may save money (by not paying administrative costs to utility).

For commercial usage, stationary solution may provide the best solution. Even utilities can use it for peak-hour demand, and businesses may bypass generators and 2nd source solutions for critical functions using simple stationary storage.
 
For residential usage, if I am using net-metering for peak-hour demand, will stationary storage still help me save money? If the solution helps me go off grid completely, then yes, I may save money (by not paying administrative costs to utility).

For commercial usage, stationary solution may provide the best solution. Even utilities can use it for peak-hour demand, and businesses may bypass generators and 2nd source solutions for critical functions using simple stationary storage.

If you live in an area where net-metering is no longer free, sure it helps save money. This battery pack will help replace net metering as the regulatory battle continues to wage on. Making solar a complete behind the meter solution has value. Net metering no longer required.
 
This battery is a far better solution than a gas generator and will help people live off grid if they pair it with solar panels... I think that pretty much says it all. Even if it's 10-20K each unit people will still pay. Costs should be near comparable to gas generators except you have the opportunity to recoup your investment without encountering disastrous situations.
 
also remember that lead acid batteries need to be "vented" and need "spill" protection/containment, and the non-sealed variety need to be checked/topped off with distilled water. Not nearly as maintainence free as Li-ion. space is also always an issue.

There are other sealed AGM-type cells which need no maintenance. But the maintenance on the ones which do need distilled water is not very often. 6-months and longer for the older technology. Li-Ion brings density into the market and in China and Japan, some Li-Ion in the form of LiFEPO4 and LiFEYPO4 are used. Denser than Lead Acid and not that expensive.
 
Going off grid is a big step. It is really hard to justify unless you live in Hawaii or even California.

Doing nightly recharging and outputting that power during the day is they key to cost savings. Some places call it peak load shaving. If your power bill shows a daytime rate of .30/kWh and night time rate of .05/kWh, then you can charge it at night and dump it during the day. The only problem is if the grid goes down - the "dump" during the day needs to have a grid-disconnect switch to disable out-flow to the grid when the battery is dumping.

There is a lot of history in off-grid power solutions for mountain homes. Li-Ion allows for full-cycle daily charge/discharge where Lead-Acid was more likely to do a 20% discharge daily for better battery longevity. Most off-gridders use 48V or 24V systems, however. With homes, you need power inversion to output 240V from a battery system. You need the ability to put out a good 240V potential from any battery system like this in order to provide the proper value to the customer. Any inversion leads to heat-losses during the AC-DC and DC-AC inversion. Using 9 kWh from a 10 kWh system needs about 12 kWh from the power source to charge it up. Depends on the charging efficiency of the inverter and cells.

10 kWh is about 240V at 10A for under four hours. If you happen to have a large A.C. unit, it probably wouldn't be wires-up with the battery standby system. I don't think that 10 kWh is enough for most homeowners. A 20 to 50 kWh solution is needed. And to go off-grid, even more. Since you need a load circuit to output the Solar PV into (hot water heater and that kind of thing) when the batteries are full. You cannot (and should not) overcharge Li-Ion cells. You can abuse Lead Acid a little bit.