Tesla Stationary Storage Investors Thread

[Causalien]

If it is plug and play, and the system is a self contained loop that doesn't feedback to the grid. I expect the Model S to be able to become part of the battery. Which provides an upsale opportunity to sell just one residential unit to all Model S owners. Or provides incentives for tree huggers to buy a used Tesla.

I would disassemble the wall charging unit to figure out if there's electronics reserved for this purpose.

 

[jhm]

If it is plug and play, and the system is a self contained loop that doesn't feedback to the grid. I expect the Model S to be able to become part of the battery. Which provides an upsale opportunity to sell just one residential unit to all Model S owners. Or provides incentives for tree huggers to buy a used Tesla.

I would disassemble the wall charging unit to figure out if there's electronics reserved for this purpose.

I'm very curious about what plug and play means in this context. I would expect that an electrician must be hired for installation, which is not really plug and play. I do expect that Tesla has made this sufficiently behind-the-meter that it does not require approval from the utility, which was an abysmal issue with DemandLogic devices. So what really is the system within which HomeGrid would be plug-and-play? One possibility is GridLogic the new microgrid from SolarCity. I would envision a whole line of components that are each plug-and-play within GridLogic. The logic here is to make it very easy to design, install and extend a microgrid. All the devices must be networkable both in terms of power and control/communication.

It is possible that the HomeGrid storage device becomes the essential link between a GridLogic microgrid and a home. I would speculate that the device can also serve as a meter. Within GridLogic it is essential to always know power in, power out and state of charge for each storage device and this information is constantly being communicated to other connected devices. Thus the HomeGrid device supports metering and billing.

Also it could serve as the gateway for solar panels, generators and any other local generation devices to connect into the microgrid. These generation devices may or may not be plug-and-play within GridLogic, but HomeGrid can serve as an intelligent integrator for all these devices into GridLogic. Thus, devices that are not plug-and-play can be integrated.

Of course, GridLogic becomes a success, then all sorts of component makers will want to make sure their devices are plug-and-play. For example an intelligent HVAC controller like Nest would want to be plug-and-play. Likewise controllers on refrigerators, hot water heaters, etc. would want to be plug-and-play. All this connectivity with HomeGrid enhances its ability to manage power needs throughout the day.

Perhaps this is something Tesla, Apple and Google have discussed.

 

[ev-enthusiast]

Analyst Trip Chowdry (Global Equities Research) has revealed some interesting information about home storage systems of Tesla that could be officially revealed end of this month in Hawthorne.
From a person that currently has a residential battery installed from Tesla, he got the following bullet points:

• "There are about 230 Households in California, who currently have Tesla Stationary Battery installed in their Homes. Another about 100 Households are out of California.
  This customer had the Tesla Stationary Battery for about One and a Half years, and is installed in his garage."
• "The Battery has to be installed 1.5 feet above the ground, and should have an open space of 1 ft on all sides.
• "The battery does not make any noise, does not need any maintenance, has no drippings."
• "The Battery has the inverter also."
• "The battery is about 3 ft tall and 2.5 ft wide and looks good."
• "The installer offered a choice between 10KWH and 15KWH; he went with 10KWH."
• "His battery can be controlled from his iPhone, and has a web application also."
• "His Battery is set for the following: Charging from Solar, and when the battery is fully charged, energy is sent to the PG&E Grid for rebate on Electric bill."
• "Charging directly from the Outlet. He does it...He charges the battery at night at $0.11 and then at 3:00 PM sells it back to Grid at $0.43. He tells me he makes between $10 to $12 every month doing this."
• "Fully off Grid. His battery can be charged by a regular generator also."
• "He has not had any problems with the Battery System...and gets OTA Software updates almost a couple of times a month."

A 10 kWh battery could be priced at $13,000 with a 50 percent rebate from PG&E Corporation.
The owner chose to pay $1,500 down and $15 per month for 10 years.
After that the installer will retrieve the battery pack.

Last year, Chowdhry attended a sustainability conference and learned that Google is "widely believed" to have a few Tesla (commercial-grade) batteries in some of its buildings.
Apple might also purchase some of these batteries for its new campus.

Chowdhry believes that Tesla's commercial-grade batteries are rated at more than 400 kWh.

 

[Causalien]

I'm very curious about what plug and play means in this context. I would expect that an electrician must be hired for installation, which is not really plug and play. I do expect that Tesla has made this sufficiently behind-the-meter that it does not require approval from the utility, which was an abysmal issue with DemandLogic devices. So what really is the system within which HomeGrid would be plug-and-play? One possibility is GridLogic the new microgrid from SolarCity. I would envision a whole line of components that are each plug-and-play within GridLogic. The logic here is to make it very easy to design, install and extend a microgrid. All the devices must be networkable both in terms of power and control/communication.

It is possible that the HomeGrid storage device becomes the essential link between a GridLogic microgrid and a home. I would speculate that the device can also serve as a meter. Within GridLogic it is essential to always know power in, power out and state of charge for each storage device and this information is constantly being communicated to other connected devices. Thus the HomeGrid device supports metering and billing.

Also it could serve as the gateway for solar panels, generators and any other local generation devices to connect into the microgrid. These generation devices may or may not be plug-and-play within GridLogic, but HomeGrid can serve as an intelligent integrator for all these devices into GridLogic. Thus, devices that are not plug-and-play can be integrated.

Of course, GridLogic becomes a success, then all sorts of component makers will want to make sure their devices are plug-and-play. For example an intelligent HVAC controller like Nest would want to be plug-and-play. Likewise controllers on refrigerators, hot water heaters, etc. would want to be plug-and-play. All this connectivity with HomeGrid enhances its ability to manage power needs throughout the day.

Perhaps this is something Tesla, Apple and Google have discussed.

I would expect the sensing logic device to be at the electrical panel between the grid and the house to detect voltage and current as well as the direction of flow. Everything else plugs into the primary battery with future batteries in a parallel configuration. Universal plugs into and out of battery for both solar city and tsla appliances.

It looks like future home's garages are increasingly becoming high tech. I sense some business opportunities to cater to this sector in 10 years. A new age home rennovation.

 

[Robert.Boston]

It does seem a shame that we've got so many DC<->AC steps going on in a typical solar+battery house:

• Solar PV generates DC power, with inverters to output AC
• Rectifiers take that AC and put it into the DC battery
• Drawing power from the battery, inverters transform the DC power to AC
• Which is then put into your Model S or other devices that have rectifiers to create DC power for on-board use.

Given how many devices in a modern household use DC, it'd be an interesting exercise to create a parallel DC network in a house to avoid all these inverter/rectifier losses.

 

[Gerasimental]

He makes $10-$12 per month but is paying $15 per month in addition to a $1500 down payment? Surely the economics have to be a bit more attractive than that.
Does the $10-$12 per month figure include the electricity he is selling from his solar panels?

 

[ScepticMatt]

It does seem a shame that we've got so many DC<->AC steps going on in a typical solar+battery house:
Given how many devices in a modern household use DC, it'd be an interesting exercise to create a parallel DC network in a house to avoid all these inverter/rectifier losses.

You're still going to need step-up/step-down DC-DC converters. But maybe Tesla can bring cost down enough.

 

[Yonki]

I'm very curious about what plug and play means in this context. I would expect that an electrician must be hired for installation, which is not really plug and play.

Well yes and no. A standard NEMA 14-30 outlet can supply 5kW to an electric dryer, so it could charge a 10kWH pack in 2 hours. And obviously it could provide 10kWH of energy back when it's needed. So in that sense it's likely to be "plug and play" - standard outlet, no need to even tell PG&E (or your local friendly utility) that you have it.

On the other hand, most people aren't going to replace their electric dryer with a battery pack, so yeah, you probably will need an electrician. A few $100 if your battery is near your fusebox...

 

[GregRF]

Well yes and no. A standard NEMA 14-30 outlet can supply 5kW to an electric dryer, so it could charge a 10kWH pack in 2 hours. And obviously it could provide 10kWH of energy back when it's needed. So in that sense it's likely to be "plug and play" - standard outlet, no need to even tell PG&E (or your local friendly utility) that you have it.

On the other hand, most people aren't going to replace their electric dryer with a battery pack, so yeah, you probably will need an electrician. A few $100 if your battery is near your fusebox...

It looks like there would be some code issues with this. It would be necessary to be a single use circuit and it seems that NEC code dictates that a backfed breaker needs to be securely mounted in the panel (not just snap in breakers).

 

[austinEV]

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

In the winter our power use is extremely low. LED lighting and gas heating. Its like $20/month.

 

[Room_A113]

He makes $10-$12 per month but is paying $15 per month in addition to a $1500 down payment? Surely the economics have to be a bit more attractive than that.
Does the $10-$12 per month figure include the electricity he is selling from his solar panels?

If his Tesla battery also acts as a whole-house backup system, then the $1500 down, plus ~$50/year could be worth it to have as a backup generator for his home. It's a bit more expensive than a portable generator, but saves in maintenance, fuel cost and noise if/when needed.

 

[austinEV]

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.

Thanks. That Ice Bear was what I was looking for. Sadly it looks like it is for commercial systems only.

 

[Yonki]

It looks like there would be some code issues with this. It would be necessary to be a single use circuit and it seems that NEC code dictates that a backfed breaker needs to be securely mounted in the panel (not just snap in breakers).

Yeah, I hadn't thought this through. Circuit breakers aren't "directional", but at the minimum there needs to be a mechanism so if the grid gets disconnected or a transformer blows you're not trying to power your whole neighborhood or electricuting the utility guy / electrician who tries to fix it. Though I wouldn't put it beyond Tesla to have some fault sensing (or even TDR) capability incorporated into their unit that could address that... Would need some regulatory approval but maybe could still be "plug and play".

 

[doggusfluffy]

It does seem a shame that we've got so many DC<->AC steps going on in a typical solar+battery house:

• Solar PV generates DC power, with inverters to output AC
• Rectifiers take that AC and put it into the DC battery
• Drawing power from the battery, inverters transform the DC power to AC
• Which is then put into your Model S or other devices that have rectifiers to create DC power for on-board use.

Given how many devices in a modern household use DC, it'd be an interesting exercise to create a parallel DC network in a house to avoid all these inverter/rectifier losses.

Also, isn't this a possible opportunity to integrate wireless charging for phones and laptop devices?

 

[techmaven]

He makes $10-$12 per month but is paying $15 per month in addition to a $1500 down payment? Surely the economics have to be a bit more attractive than that.
Does the $10-$12 per month figure include the electricity he is selling from his solar panels?

The article write up is definitely vague.

If the homeowner charged the entire 10kWh at night and then sold back the power during peak for a difference of $0.32 per kWh, the revenue per day is $3.20 or $96/month or $1,168 per year. Or $11,680 per decade.

Obviously that is not what is going on. $12/month represents only 37.5 kWh, or about 1.25 kWh per day. So chances are the setup is designed to fill the battery at night to only to (capacity - predicted morning/early afternoon solar generation). Say that's 60%. During breakfast and while the solar panels are not producing all that much, the battery is being used. Then the solar panels kick in when the sun rises sufficiently, filling to max capacity (which isn't 100% SoC) by 3:00pm. At 3:00pm, the system sells stored power back to the grid + solar generation, but leaving enough for the expected household use at night. As the sun goes down and people use power in the house, the household uses the stored power in the battery pack. The net effect is selling 1-1.25 kWh per day, but also usually zero grid power usage during anytime other than off-peak hours at $0.11.

So if the power pack is sized big enough to cover the entire household electricity usage on a daily basis, the entire power bill equation looks like:

(household power usage - solar power generation) * 1.1 * $0.11 + (grid power used in excess of battery pack) * 0.45 (or something like that) + $15 lease cost

If the household uses 8kWh per day outside of high peak and generates 4 kWh per day in solar outside of peak, and another 1 kWh during peak hours, that's charging to 60% at super off peak at $0.11. Then the sun charges the panels to near 100% until 3:00pm, at which time the battery discharges into the grid for 1 kWh and also the solar panels kick in a little more. Going into the evening hours, the battery pack has 9 kWh and if the household uses 6 more kWh and so the pack has 3 kWh leftover at the start of super-off peak. It then charges 3 kWh at $0.11, back to 60% and begins another cycle. If the household uses 12 kWh that evening, the battery is depleted and the household uses the grid for 4 kWh that evening. The battery pack is then charged again to 60%, but maybe the pack chooses to avoid selling power to the grid the next day if the usage is high again. Not sure how the algorithm learns or is tweaked.

 

[Yonki]

This thread seems to be focusing on the residential, but I think we should consider the commercial market as well. I have the feeling the ROI is much better for companies than individuals, and there is an enormous market there.

Although I'm sure there are a lot of people that would probably dedicate a small chunk of floor space in their garage for something that will save them $700 - $1000 annually... That ain't nothin...

 

[andrewket]

This thread seems to be focusing on the residential, but I think we should consider the commercial market as well. I have the feeling the ROI is much better for companies than individuals, and there is an enormous market there.

Although I'm sure there are a lot of people that would probably dedicate a small chunk of floor space in their garage for something that will save them $700 - $1000 annually... That ain't nothin...

Except the commercial product already exists. Tesla has been shipping a commercial solution for almost a year, I believe. But they may be "launching" it as generally available now.

 

[mitch672]

Yeah, I hadn't thought this through. Circuit breakers aren't "directional", but at the minimum there needs to be a mechanism so if the grid gets disconnected or a transformer blows you're not trying to power your whole neighborhood or electricuting the utility guy / electrician who tries to fix it. Though I wouldn't put it beyond Tesla to have some fault sensing (or even TDR) capability incorporated into their unit that could address that... Would need some regulatory approval but maybe could still be "plug and play".

I'm absolutley sure its a "synchronis" inverter, meaning if the grid power is not present, the pack shuts down
to do anything else requires a much more involved/costly installation with a "transfer switch", to isolate the house from the grid, which is possible, but more than likely involves extra cost on the installation.

 

[ScepticMatt]

I'm absolutley sure its a "synchronis" inverter, meaning if the grid power is not present, the pack shuts down.

I remember reading from SolarCity/Tesla users here that this is not the case. There was a power outage and battery power kicked in without interruption.

 

[mitch672]

I remember reading from SolarCity/Tesla users here that this is not the case. There was a power outage and battery power kicked in without interruption.

It has to meet UL 1741
Scope for UL 1741

Table of Contents for UL 1741