Tesla Stationary Storage Investors Thread

[glhs272]

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.

Ok, some quick cocktail-napkin analysis. It takes about an hour to get a 0 to 80% supercharge. To get 80% capacity into a 60 battery, that would be about 44kWh=(.8 x 55kwh) [55kwh being usable capacity of the battery]. On a 85 battery 62kWh=(.8 x 78) [78kWh being usable capacity of an 85]. My designed system would include grid tied chargers (twin chargers) that would always put out a constant 20kW. So over the course of the supercharge, I would receive about 20kWh for that session from the grid directly. So, therefore the battery would only need to proved the remaining 24kwh for a 60 and 42kwh for a 85 kwh car. Therefore the ideal system would be a modular system with two battery choices, a 25kWh battery for owners of 60kWh cars and a 50kWh (think twin battery) for 85kWh car owners. This system would allow for an at home supercharger experience (0 to 80% anyway). After 80% the battery would no longer contribute and it would just run off the system's grid connected twin chargers, so the system would taper off to 20kw during the 80 to 100% charge. I wouldn't think that would be much of a problem anyway considering the car is already heavily tapering at that point anyway (especially a 60kWh car). Once the car unplugs from the supercharger, the system's twin chargers would recharge the house battery at 20kW using the grid (plus any available solar energy if equipped and available).

So there is my system. Consists of a 25 or 50 kWh battery, a dedicated 10kW grid to battery charger (or twin chargers for 20kW), an inverter to power house functions when not being used as a supercharger, optional solar connection, a DC to DC controller and a system controller. The system controller could be programed to administer the supercharge session, manage loads for the house power draw, manage battery recharge times for optimal TOU, and incorporate solar charging of the battery as well. This system could be used to store energy to reduce TOU charges, used as a supercharger when necessary, can provide solar to car charging, backup power in case of grid outage, and of course store unused solar energy. This system would still be using the grid.

Basically a lot like wk057's setup but with a lot smaller battery and the option to directly charge DC to DC.

 

[Robert.Boston]

There is a real business proposition in giving the grid operator access to the in-home/in-business battery. The flexibility of these units, taken as a whole across a control area, would help integrate higher levels of variable renewables (e.g. solar & wind) and reduce the need to keep large amounts of flexible fossil-fired generators on-line to provide regulation and reserves. In order to provide these services, the battery system will need to be fitted with some 'smarts' and an Internet connection, the cost of which is trivial compared to the potential earnings.

Unfortunately, the fate of such demand-side participation in the wholesale power markets is very much up in the air. The power-plant owners' association, the Electric Power Supply Association, succeeded in getting the D.C. Court of Appeals to strike down FERC Order 745. That order required system operators to pay DR when it was cost-effective. The order had a pretty serious flaw in it, which is why EPSA took it to court. The court went far beyond what anyone expected, though, and ruled that Order 745 was illegal because it over-stepped federal authority, that customers (at the distribution level) were exclusively a state matter. The utility FirstEnergy has already filed suits to force existing demand-side programs out of its system's marketplace.

Because all the system operators (including New York and California, but excepting Texas) are federal creations, there is now the very real question of how, if at all, homeowners and small businesses can actively participate in power markets. The matter has been appealed to the SCOTUS, which has not yet acted.

 

[nwdiver]

Because all the system operators (including New York and California, but excepting Texas) are federal creations, there is now the very real question of how, if at all, homeowners and small businesses can actively participate in power markets. The matter has been appealed to the SCOTUS, which has not yet acted.

Hopefully as SCTY and TSLA become more profitable they will gain more power and political clout enabling them to effect some change in this regard.

 

[Lessmog]

There is a real business proposition in giving the grid operator access to the in-home/in-business battery. The flexibility of these units, taken as a whole across a control area, would help integrate higher levels of variable renewables (e.g. solar & wind) and reduce the need to keep large amounts of flexible fossil-fired generators on-line to provide regulation and reserves. In order to provide these services, the battery system will need to be fitted with some 'smarts' and an Internet connection, the cost of which is trivial compared to the potential earnings.

Unfortunately, the fate of such demand-side participation in the wholesale power markets is very much up in the air. The power-plant owners' association, the Electric Power Supply Association, succeeded in getting the D.C. Court of Appeals to strike down FERC Order 745. That order required system operators to pay DR when it was cost-effective. The order had a pretty serious flaw in it, which is why EPSA took it to court. The court went far beyond what anyone expected, though, and ruled that Order 745 was illegal because it over-stepped federal authority, that customers (at the distribution level) were exclusively a state matter. The utility FirstEnergy has already filed suits to force existing demand-side programs out of its system's marketplace.

Because all the system operators (including New York and California, but excepting Texas) are federal creations, there is now the very real question of how, if at all, homeowners and small businesses can actively participate in power markets. The matter has been appealed to the SCOTUS, which has not yet acted.

I don't much like the sound of that saga, even on the face of it.
But a friendly reminder: There are other countries, other jurisdictions, and so other potential markets.
Of course it'd be nice to have a home market available.

 

[mwulff]

I would point out that there is a global market where 10 kWh of storage means that you can run your house on stored energy for 24-36 hours. I just checked and over the last 24 hours my House used 10.5 kWh of electricity.

If I had a tesla unit I got have stayed off the grid for that 24 hour period and paid no taxes on electrical power. This product could be very valuable in countries where power usage is less than the enormous amounts traditionally used by a U.S. household.

And if they stack they are even more valuable. As for quick charging I don't think it makes a lot of sense. A super charger in your home sounds nice but ultimately your car has enough time at home to charge slowly.

 

[cziegler]

Stationary Storage/DC Fast Charging

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.

My thoughts precisely; heck, if I'm going to invest in batteries for disaster prepardness, UPS/conditioned power for data systems, peak shaving etc. may as well have the ability to DC fast charge an EV. I think even only being able to add 20 or 30 miles of range via DC charging would help buffer against the rare times when someone forgets to plug in the night before and learns of low range as they prepare to depart on errands the next day - This may even save marriages

 

[austinEV]

Ok, here is a question I have always had. Suppose you live in the sun belt. Most of the electricity you use, is for air conditioning. Most of that electricity is used in compressing coolant into a liquid:

I don't really need a battery, I would be fine just storing compressed coolant. Why not add big coolant tanks to that refrigeration cycle, which for my purposes is like stored energy? During the day when Solar power is available, the compressor ejects heat from the coolant and fills the tank. In the evening, and during the night, the liquid coolant is pumped into the evaporator as needed for cooling? A few tanks has to be cheaper than a 10kWh battery pack and will do the same job of energy offsetting.

 

[EldestOyster]

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.

You don't suppose that a company as smart as Tesla could come up with a system to manage a bank of these (assuming lead acid batteries actually had some compelling properties)? I do; after all, they currently build a car safely powered by sticks of dynamite

 

[Auzie]

I would point out that there is a global market where 10 kWh of storage means that you can run your house on stored energy for 24-36 hours. I just checked and over the last 24 hours my House used 10.5 kWh of electricity.

If I had a tesla unit I got have stayed off the grid for that 24 hour period and paid no taxes on electrical power. This product could be very valuable in countries where power usage is less than the enormous amounts traditionally used by a U.S. household.

And if they stack they are even more valuable. As for quick charging I don't think it makes a lot of sense. A super charger in your home sounds nice but ultimately your car has enough time at home to charge slowly.

It is amazing how much power an ordinary household can save just by changing few small habits.

My expectation is that if someone has a home battery storage of an adequate size, that household would quickly adjust and learn how to stay within the size boundaries without loss of lifestyle.

 

[30seconds]

Ok, here is a question I have always had. Suppose you live in the sun belt. Most of the electricity you use, is for air conditioning. Most of that electricity is used in compressing coolant into a liquid:



I don't really need a battery, I would be fine just storing compressed coolant. Why not add big coolant tanks to that refrigeration cycle, which for my purposes is like stored energy? During the day when Solar power is available, the compressor ejects heat from the coolant and fills the tank. In the evening, and during the night, the liquid coolant is pumped into the evaporator as needed for cooling? A few tanks has to be cheaper than a 10kWh battery pack and will do the same job of energy offsetting.

What do you do in winter? I think the idea is that the battery is way more flexible - in summer you can use to run the AC or the lights or whatever - to your energy company the only thing that matters is net use, not how you use it

 

[Robert.Boston]

I don't really need a battery, I would be fine just storing compressed coolant. ... A few tanks has to be cheaper than a 10kWh battery pack and will do the same job of energy offsetting.

You're right in many regards, but the power in a battery is completely fungible, whereas the compressed coolant is only useful to offset part of your AC energy. You can't run your computer or power your car from compressed coolant.

BTW, what many big buildings do is to chill or warm a large pool of water in a sub-basement overnight, then use the stored heat/cool to assist the building's HVAC. That's been going on for a century or so in NYC. You can replicate this at home with a system like the Ice Bear. Using ice instead of compressed coolant seems to be more efficient because ice stores so much energy in the phase shift from liquid to solid.

 

[drinkerofkoolaid]

Solar City currently has around 200,000 customers. If each customer gets a 3 kWh battery system, that's a lot of batteries, and a lot of profit for Tesla and Solar City. Solar City is aiming to have 1 million customers by 2018. 1 million customers with a 3 kWh battery system = A LOT of batteries.

Also, each Solar City customer is likely to give strong consideration to buying a Tesla.

 

[Johan]

Solar City currently has around 200,000 customers. If each customer gets a 3 kWh battery system, that's a lot of batteries, and a lot of profit for Tesla and Solar City. Solar City is aiming to have 1 million customers by 2018. 1 million customers with a 3 kWh battery system = A LOT of batteries.

Also, each Solar City customer is likely to give strong consideration to buying a Tesla.

To pull this off they need A LOT of cells. Gigafactory 1 is underway but it seems it will be mostly for car batteries? If we see GF 2 and 3 announced in 2015 or 2016 we will know they mean business will develop very rapidly.

 

[FANGO]

Also, each Solar City customer is likely to give strong consideration to buying a Tesla.

EV + solar really is a game changer, the ideas are great on their own but together they synergize so well. 30% of EV owners in CA have solar. So there will definitely be cross business opportunities here.

 

[drinkerofkoolaid]

To pull this off they need A LOT of cells. Gigafactory 1 is underway but it seems it will be mostly for car batteries? If we see GF 2 and 3 announced in 2015 or 2016 we will know they mean business will develop very rapidly.

Solar Power and Battery Backup: Tesla and SolarCity's Dream Home [Archive] - Tesla Motors Club - Enthusiasts & Owners Forum

"I purchased a SolarCity PV system and was offered the chance to lease a 10 kWh battery system for $10/mo for 10 years."

Solar City can depreciate the asset, allowing it to reduce the amount its customers pay. Individual home owners who choose to buy the Battery Backup can't depreciate the asset. I'd imagine this has a very significant effect on the cost of battery backup systems.

How Battery Storage Will Change the Household Energy Market

Also, according to this article that discusses the significance of microgrids, there are currently in excess of 12 million backup generators in the United States.

In Backup Generators We Trust?

 

[ScepticMatt]

1 million customers with a 3 kWh battery system = A LOT of batteries.

That's 3 GWh spread over a few years. Tesla aims to sell 15 GWh per year as soon as the Gigafactory hits full production.

To pull this off they need A LOT of cells. Gigafactory 1 is underway but it seems it will be mostly for car batteries?

Raw cells made at the Gigafactory will be exclusively for cars (35 GWh), but Tesla will still import 15 GWh worth of cells for home energy storage.
The Gigafactory targets 50 GWh worth of pack output per year (35+15)

 

[drinkerofkoolaid]

My guess is the size of the battery storage system will vary depending on the needs of the customer.

Also, that doesn't account for other companies that partner with Solar City. There already are quite a few, including the US Government, Walmart, and Direct TV, to name a few.

I think Elon mentioned at some point that 30-40% of the batteries produced at the Gigafactory will be for grid storage? Anyone know the statement I'm thinking of?

Also, late last year, Lyndon Rive mentioned he expects EVERY Solar City Customer to have battery backup within 5-10 years.

Every SolarCity Customer Will Get Battery Backup Within 5-10 Years

 

[eloder]

I imagine it'll be tremendously huge for commercial markets.

There are many businesses out there with basements full of lead-acid batteries, backed up by a generator, which is backed up by a second generator. I can only imagine that many of those businesses would love for a more cost-effective option, and I think the tectonic shift for this will be costs for going LiOn.

I also wouldn't be surprised if Tesla will allow this new tech to allow superchargers in many more locations where it normally wouldn't be possible, as well as the ability to handle max-discharge SC speeds under peak loads.

The primary use homeowners will see will be time of use schedules. Buy electricity at night, use during day, and solar situations. Even non-solar households would likely have a fairly small ROI under a strict time of use metering. I wouldn't be surprised to see a Tesla battery behind each and every SCTY installation in a time of use area, added in free of charge, due to the savings it would generate.

 

[mitch672]

You don't suppose that a company as smart as Tesla could come up with a system to manage a bank of these (assuming lead acid batteries actually had some compelling properties)? I do; after all, they currently build a car safely powered by sticks of dynamite

we are talking about TESLA here, right? they will not be using any lead acid batteries in ANYTHING they manufacture.
They've had enough issues with the AGM 12V batteries in the Model S, to steer clear of them for good, most likely.

 

[Larken]

If there was a time to announce GF #2, it would be on April 30th, just sayin'....