Tesla Powerwall

[edatoakrun]

...I do believe that Elon is on a mission here - not just to make money. ...

If so, a mission likely doomed to failure, IMO

="Slow1"...Load balancing for utilities is indeed an important part of a long term strategy...

Yes, BEV batteries have will be an important component of the future grid, but Tesla has pursued policies that will probably make it's products batteries useless for these goals.

There are two major future applications for BEV batteries in grid stabilization/load balancing.

The first is using the BEV batteries while they are in the vehicle.

This requires widespread installation of DC charger/Vehicle to grid devices at useful locations, mostly homes and workplaces.

Tesla instead "Free" supercharger policy, means VtoG is economically impossible.

Sad to say, that huge battery in every S will probably never be available to meet grid demand, not while parked at work, nor while parked in every S owners garage.

Which is part of why Tesla is now trying to sell S owners even more batteries for their garage.

The second application of BEV batteries is in repurposing them is stationary applications, after they lose enough of their initial capacity/energy density to make replacement desirable.

The complexity and cost of using Tesla batteries, which require thermal management for safety reasons, probably makes them a poor choice in most new installations.

IMO, trying to repurpose used S packs for this application involves so many additional challenges, it will probably never happen on any scale.

 

[dgpcolorado]

...Hmm, I have a 200amp master breaker in my main panel. I wonder if I turned everything in my house on if I could come close to tripping it?...

I also have 200 amp service and I couldn't remotely trip that breaker with everything on. My big power draws are the LEAF (3.8 kW), followed by my home theater (>1kW), and the furnace blower. Use gas for the stove and on-demand water heater, and don't own a clothes dryer (use clothes lines in my utility room). No AC, of course; I have the great outdoors at night for summer cooling. Before my solar panels I averaged 4.8 kWh per day, more in winter and less in summer.

Since I am on a flat rate plan (13.77¢/kWh) and solar covers 100% of my usage, there is no way this Tesla battery would be cost-effective. And our power here is very reliable, with outages very infrequent and brief, so no benefit as a backup for outages.

I would think that these units have the most utility for those with very high rate TOU plans as well as commercial users who are on demand rate plans. Lowering peak demand for commercial users could be lead to very big savings.

 

[Zythryn]

...I do believe that Elon is on a mission here - not just to make money. ...

If so, a mission likely doomed to failure, IMO

Considering how consistently negative you have been about Tesla, and your track record of being wrong, I don't put a lot of faith in your opinion :roll:

 

[smkettner]

Here in NJ if I want a time of use meter, I get to pay $11.75 per month for the privilege, and our rates would be, I think, 11 cents and 18 cents, so I wouldn't even get back the service charge in savings.

Here in Southern California my overnight rate is 11 cents and weekday on-peak is 36 cents winter and 46 cents Summer. So the ratio is closer to 4:1 here.

 

[mbender]

If so, a mission likely doomed to failure, IMO

Considering that Musk went into both SpaceX and Tesla knowing that the odds were well against him, with plenty of naysayers (including friends) telling him not to or that he would fail, and his track record of success, I wonder where the smart money is headed. I think he and his now formidable team, along with additional gigafactories, will find a way to make it work, even if they have to modify what they are offering. They are [thinking] years ahead of any other company, let alone any "industry" as a whole.

...I do believe that Elon is on a mission here - not just to make money. ...

If so, a mission likely doomed to failure, IMO

Considering how consistently negative you have been about Tesla, and your track record of being wrong, I don't put a lot of faith in your opinion :roll:

 

[Nubo]

Tesla energy is skating to where the puck is going to be. There's a growing dislike of net-metering by the utilities now that solar has proliferated. And for legitimate reasons -- someone who is paying $0 but using the grid as their "battery" is not paying for the (rather substantial) cost of that grid. Some of the current arrangements are unsustainable both logistically and politically. As leader of Solar City, surely Musk has a pretty good idea of where this is going.

Going totally off-grid will probably continue to be an edge case for some time. But I think lots of folks will be looking more closely at storage when the currently fabulous metering advantages fade, in order to get the most benefit from their solar installations. And of course battery technology won't be standing still. Not everybody has to rush out and get it on day one, for it to be successful long-term.

 

[Slow1]

Here in NJ if I want a time of use meter, I get to pay $11.75 per month for the privilege, and our rates would be, I think, 11 cents and 18 cents, so I wouldn't even get back the service charge in savings.

Here in Southern California my overnight rate is 11 cents and weekday on-peak is 36 cents winter and 46 cents Summer. So the ratio is closer to 4:1 here.

So assuming best case all the way around, you could save $3.50/week day. 5 days a week that is $17.50/week. If you get the system installed for $5k then you are looking at about 5.5 years to break even. I think I saw somewhere mention of a 10 year warranty so it does seem that this system COULD be financially viable in your case.

Tesla energy is skating to where the puck is going to be. There's a growing dislike of net-metering by the utilities now that solar has proliferated. And for legitimate reasons -- someone who is paying $0 but using the grid as their "battery" is not paying for the (rather substantial) cost of that grid. Some of the current arrangements are unsustainable both logistically and politically. As leader of Solar City, surely Musk has a pretty good idea of where this is going.

I have to agree that this appears to be the most likely scenario. In areas that don't have net metering (yes they exist) it may well be that this option could make solar more palatable. Considering the same numbers as above (use 5 days a week which in a very sunny location may be a decent estimate for average), the 10 year cost is $5k, recovering 50kWh/week that may have gone to waste would be about 19.2c/kWh over 10 years.

 

[abasile]

Tesla energy is skating to where the puck is going to be. There's a growing dislike of net-metering by the utilities now that solar has proliferated. And for legitimate reasons -- someone who is paying $0 but using the grid as their "battery" is not paying for the (rather substantial) cost of that grid. Some of the current arrangements are unsustainable both logistically and politically. As leader of Solar City, surely Musk has a pretty good idea of where this is going.

Going totally off-grid will probably continue to be an edge case for some time. But I think lots of folks will be looking more closely at storage when the currently fabulous metering advantages fade, in order to get the most benefit from their solar installations. And of course battery technology won't be standing still. Not everybody has to rush out and get it on day one, for it to be successful long-term.

This is an excellent post, IMHO. Further, in the years ahead as prices drop, many "turn key" solar installations will be bundled with batteries.

At utility scale, it will be interesting to see if PV+batteries completely displaces solar thermal. (The principal advantages of solar thermal over PV today are (a) the ability to time shift generation later into the evening and (b) reduced power fluctuation due to short-term changes in cloud cover. OTOH, solar thermal plants seem somewhat complex to operate.)

 

[thankyouOB]

Tesla energy is skating to where the puck is going to be. There's a growing dislike of net-metering by the utilities now that solar has proliferated. And for legitimate reasons -- someone who is paying $0 but using the grid as their "battery" is not paying for the (rather substantial) cost of that grid. Some of the current arrangements are unsustainable both logistically and politically. As leader of Solar City, surely Musk has a pretty good idea of where this is going.

Going totally off-grid will probably continue to be an edge case for some time. But I think lots of folks will be looking more closely at storage when the currently fabulous metering advantages fade, in order to get the most benefit from their solar installations. And of course battery technology won't be standing still. Not everybody has to rush out and get it on day one, for it to be successful long-term.

Here in LA, the municipal utility charges $8 a month as a service charge to solar users. I would think that covers the cost of being wired in, or at least minimizes it.
the rates on TOU are three tiers ranging from about 8 cents a kwh nites and weekends to 22 cents for daytime 1-5pm in summer 4 months.
i dont see that the tesla battery pays off except in outages and for us, as we care about whether we are adding to ghg and other air pollution and water (from resource extraction) use and pollution.

is it worth the price?
we will see.

 

[dgpcolorado]

Here in LA, the municipal utility charges $8 a month as a service charge to solar users. I would think that covers the cost of being wired in, or at least minimizes it...

I think that's about right.

Here I pay $16/month but my rural power co-op has said the actual infrastructure cost is in the $20-25/month range if evenly distributed, so we net meter customers are currently being subsidized because the co-op membership strongly supports renewables. Our co-op has lines and facilities scattered over hundreds of square miles of mountains for only a few tens of thousands of meters. In my rural neighborhood we have all underground lines, spread over many square miles, serving perhaps 350 houses; I even have my own transformer that serves just my house. I find it remarkable that they are able to do so much, so well, at so little cost.

In your much more densely populated location the economies of scale might well lead to a fair $8/month service charge.

 

[NeilBlanchard]

The Tesla battery does not include an inverter, so you need to add another few percent loss for that (each way unless you are charging directly from DC PV).

I am not sure where this "fact" came from. If you listen to his presentation, he say that it is ready to go into a solar system "right out of the box". It is compatible with single phase and three phase utility grid.

[youtube]https://www.youtube.com/watch?v=yKORsrlN-2k[/youtube]

The Powerwall is 2kW continuous, and 3.3kW peak.

 

[RegGuheert]

The Tesla battery does not include an inverter, so you need to add another few percent loss for that (each way unless you are charging directly from DC PV).

I am not sure where this "fact" came from. If you listen to his presentation, he say that it is ready to go into a solar system "right out of the box". It is compatible with single phase and three phase utility grid.

[youtube]https://www.youtube.com/watch?v=yKORsrlN-2k[/youtube]

The Powerwall is 2kW continuous, and 3.3kW peak.

From Tesla's main page on the Powerwall:

DC-AC inverter not included.

 

[palmermd]

The Tesla battery does not include an inverter, so you need to add another few percent loss for that (each way unless you are charging directly from DC PV).

I am not sure where this "fact" came from. If you listen to his presentation, he say that it is ready to go into a solar system "right out of the box". It is compatible with single phase and three phase utility grid.

[youtube]https://www.youtube.com/watch?v=yKORsrlN-2k[/youtube]

The Powerwall is 2kW continuous, and 3.3kW peak.

From Tesla's main page on the Powerwall:

DC-AC inverter not included.

Yes, but it does include the DC-DC, so it would work with a solar system "right out of the box". If you don't have a solar system then you would need to add a ac-dc in order to charge the battery and then a dc-ac inverter to power the home.

 

[Slow1]

Yes, but it does include the DC-DC, so it would work with a solar system "right out of the box". If you don't have a solar system then you would need to add a ac-dc in order to charge the battery and then a dc-ac inverter to power the home.

Ok, let me see if I understand this...

The "out of the box" configuration has a charge controller to allow you to charge the battery from solar DC current? But it doesn't have DC-AC conversion so you would then use the solar inverter to pull the power out of the batteries?

 

[RegGuheert]

Yes, but it does include the DC-DC, so it would work with a solar system "right out of the box". If you don't have a solar system then you would need to add a ac-dc in order to charge the battery and then a dc-ac inverter to power the home.

Ok, let me see if I understand this...

The "out of the box" configuration has a charge controller to allow you to charge the battery from solar DC current? But it doesn't have DC-AC conversion so you would then use the solar inverter to pull the power out of the batteries?

No way is the DC-DC converter included in the Tesla PowerWall a charge controller. Likely it serves two (or perhaps three) purposes: 1) Regulate the voltage of the battery to a standard value (which Tesla chose for this and all future versions), 2) allow for multiple units to properly share loads when connected in parallel, and possibly 3) limit the output current the battery can deliver to a safe level in case of a short on the output.

If you want to include this in a standalone PV system, you will need to add an MPPT charge controller to maximize your energy harvest and an inverter if you want to use standard AC wiring. Unfortunately, I am not aware of any charge controllers or inverters for home use which work at such a high DC voltage. Tesla apparently wants to create a new standard for DC voltages for PV systems.

 

[palmermd]

I agree that they are lacking a lot of detail information about how it really interconnects in the real world. In his presentation video he clearly states what it does and his "out of the box" statement, but I'd like to see more detail about how it connects to an existing grid connected solar system as opposed to an existing off grid system. The video statement occurs at about 8:15 to 8:30 in the presentation. https://www.youtube.com/watch?v=ZVjW9XdPlhg" onclick="window.open(this.href);return false;

 

[Slow1]

I agree that they are lacking a lot of detail information about how it really interconnects in the real world. In his presentation video he clearly states what it does and his "out of the box" statement, but I'd like to see more detail about how it connects to an existing grid connected solar system as opposed to an existing off grid system. The video statement occurs at about 8:15 to 8:30 in the presentation. https://www.youtube.com/watch?v=ZVjW9XdPlhg" onclick="window.open(this.href);return false;

Just looked at the specs and I see:

Compatibility
Single phase and three phase utility grid compatible.

and then:

Installation
Requires installation by a trained electrician. DC-AC inverter not included.

I wonder if perhaps they are saying that it does in fact have the basic DC/AC linkage to connect ot single or three phase utility power (i.e. AC) but that the DC-AC inverter required for solar installs insn't included?

Another area on the page has:

Energy Security
Powerwall automatically switches to battery power in the event of an electric company outage, bringing peace of mind to those who live in areas prone to storms or unreliable utility grids.

Which would require that the Powerwall have a way to detect the failure and disconnect the circuits protected by the unit from the grid. I can see many possible options to solve this...

I would really like to see the installation manual for this as it likely would help answer a lot of questions eh?

 

[RegGuheert]

Expect to see SolarCity (labeled, possibly manufactured by Tesla or a third party) charge controllers and inverters in the near future that are designed to work with the Powerwall. You should also expect to see three-phase inverters coming for commercial applications, possibly also from SolarCity. Moving the voltage up to 400VDC is actually a very clever strategy that eliminates ALL existing charge contoller and inverter manufacturers from the market so that Tesla can control all of the components that interface with the Powerwall. (Not to mention the fact that higher voltages provide better overall efficiency and also simplify the design of overcurrent protection devices. Safety is the main drawback, but that can be addressed.)

 

[LTLFTcomposite]

Which would require that the Powerwall have a way to detect the failure and disconnect the circuits protected by the unit from the grid. I can see many possible options to solve this...

How do grid tied systems today prevent backfeeding during an outage? With backup generators this is supposedly a big deal.

 

[Slow1]

Which would require that the Powerwall have a way to detect the failure and disconnect the circuits protected by the unit from the grid. I can see many possible options to solve this...

How do grid tied systems today prevent backfeeding during an outage? With backup generators this is supposedly a big deal.

A standard grid-tie inverter constantly monitors and syncs with the line power, if the line goes out of a set range, the inverter automatically goes offline and 'watches' for the power to come back.

The PW would have to be a bit more sophisticated as it isn't just going to go off-line; it is going to create a power island. More like an automatic backup generator that has to do the same (cut link to grid and come online to power the 'island' then when grid is back for set time period transition back). The Grid Tied solar inverter simply has to shut down and wait to come back.