Tesla Wants to Build a Battery for Your House

[Amy@altE]

Amy, you missed the point of why this is targeted at solar. You analysis is for off grid. This product is about shifting usage on grid to avoid purchasing expensive power.

If the ROI is positive on a financed system, buying it is a rational decision. The system is sized at 7kwh probably looking at typical grid supplied electricity from a smaller residential solar system. (perhaps a 6 kw array is typically sending the grid 3-4kwh during a typical sunny day).

The bigger picture is the question "Is solar cost effective without incentives and with rational electric rates". As you point in your numbers, it's not unless one believes in man made climate change.

But if this is nothing new, please tell me where I can buy a maintenance free 7kwh system with a ten year warranty for $3K.

I'm just playing devil's advocate. He said he wants to use these to replace fossil fuel. 7kWh isn't going to do that, which is why I scaled it up to an "average" size home usage.

I totally agree that maintenance free is the key here, Trojan's Industrial battery line comes within that price point, but I know a very small fraction of the population who would be able to keep them alive for over a decade.

The ROI is barely there on a financed grid-tied system without incentives, my point is increasing the cost to add batteries is going to greatly limit the number of homes that this is viable for. I'm assuming the 30% fed incentive will not be renewed next year, so it will be up to local incentives, which are currently sketchy at best.

Believe me, I want this to succeed, I'm just trying to add realistic numbers to the marketing hype. Awareness is good, and Elan Musk can certainly get a message out there.

[Edge of Nowhere]

Yup

Use a Trojan Industrial battery with 60 years of track record in fork lifts. They have 8 year warranty and current testing indicates they are a 10 to 15 year battery cycles to 80% DOD. No one comes close to that at any price point. The Trojan Industrial line is the only battery out there to pass IEC 61427 testing so far up to 2500 cycles and still counting. Best bang for the buck at $300-Kwh.

I was just reading your post about the recent testing Trojan has been working on, I will be buying Trojan batteries. I will be starting out with a single string of 105RE's, collecting data and some real life experience, I hope not to destroy them but we all pay for our education one way or another.

[Sunking]

I have been waiting for this announcement before I buy batteries for my new off grid home, I had no real hopes of it being a viable option and now I know. Vaporware, no real specifications have been shared to determine the viability. The risk of riding the bleeding edge is not worth it, I will will cut my teeth on some proven FLA GCs. It is a new home with no historical data only estimated need so I fully expect the batteries to be abused and misused while we get everything tuned, hopefully there will be some real world data and proven results when it comes time to replace them.

Use a Trojan Industrial battery with 60 years of track record in fork lifts. They have 8 year warranty and current testing indicates they are a 10 to 15 year battery cycles to 80% DOD. No one comes close to that at any price point. The Trojan Industrial line is the only battery out there to pass IEC 61427 testing so far up to 2500 cycles to 80% DOD and still counting. The test has been running since 2009 by independent test labs and Trojan. Its the real deal. Best bang for the buck at $300-Kwh.

[Edge of Nowhere]

No real specs nothing to see here

I have been waiting for this announcement before I buy batteries for my new off grid home, I had no real hopes of it being a viable option and now I know. Vaporware, no real specifications have been shared to determine the viability. The risk of riding the bleeding edge is not worth it, I will will cut my teeth on some proven FLA GCs. It is a new home with no historical data only estimated need so I fully expect the batteries to be abused and misused while we get everything tuned, hopefully there will be some real world data and proven results when it comes time to replace them.

[Sunking]

Elon said the system would work 'out of the box' with existing solar setups... As there is no inverter that comes with the battery, is it safe to assume this battery would integrate then into an existing inverter?

No it is not Safe to say that as it is not possible.

How is the battery charged? There are no charge controllers for a 450 volt battery, nor are there any off the shelf inverters. So how does it interconnect? No one can answer as it does not exist.

From the add it clearly states to be used to offset peak rates. That tells me it is intended to be charged by the Grid or a Grid Tied Solar System, and the energy released during Peak Hours. How much of that 7 Kwh is usable is mystery, but still waste a lot of energy that could be better utilized. Bottom line battery systems are loosers no matter how you spin it.

The real issue is conventional power generation as there is not enough of it. California is getting exactly what they asked for. SCREWED and the people who live there like it that way.

[donald]

Amy, you missed the point of why this is targeted at solar. You analysis is for off grid. This product is about shifting usage on grid to avoid purchasing expensive power.

If the ROI is positive on a financed system, buying it is a rational decision. The system is sized at 7kwh probably looking at typical grid supplied electricity from a smaller residential solar system. (perhaps a 6 kw array is typically sending the grid 3-4kwh during a typical sunny day).

The bigger picture is the question "Is solar cost effective without incentives and with rational electric rates". As you point in your numbers, it's not unless one believes in man made climate change.

But if this is nothing new, please tell me where I can buy a maintenance free 7kwh system with a ten year warranty for $3K.

[SunEagle]

I just watched his announcement. His big (declared) focus is to use the batteries to replace fossil fuels with renewables, primarily solar. Note that saving homeowners money was not a stated objective, saving the planet was. <insert climate change deniers' comments here>.

But, let's do the extremely simplified ROI math.

The PowerPack batteries can be stacked up to 9. The 10kWh is for back-up, the 7kWh is for daily cycling, so let's play with that one. I haven't seen the specs for DoD, but let's use 50% for kicks and giggles (I am not well versed in lithium yet). 7kWh x 9 packs x 30 days a month x .5 DoD = 945kWh a month. That's maybe in the low to average usage range. $3000 x 9 = $27k, without the inverter(s) and solar. Let's pair that with a 10kW PV system, installed for $3/W, another $30k, to make the math easy, I'll throw in another $3k for the inverter or converter, assuming it needs something, totaling $60k for 945kWh a month. At $0.18 per kWh from the grid, that's $170 / month. That's 30 years ROI, except the batteries will not last 30 years, so there is no ROI without huge incentives. Unless saving the planet is considered a good return on investment ; )

I think there's nothing new about the announcement, except now there's a lot of marketing money and coolness factor put behind the old message of grid-tied battery backup solar systems.

You have to remember that Musk has his fingers in solar PV as well as batteries. Sell more of both would be a big profit for him.

[Amy@altE]

I just watched his announcement. His big (declared) focus is to use the batteries to replace fossil fuels with renewables, primarily solar. Note that saving homeowners money was not a stated objective, saving the planet was. <insert climate change deniers' comments here>.

But, let's do the extremely simplified ROI math.

The PowerPack batteries can be stacked up to 9. The 10kWh is for back-up, the 7kWh is for daily cycling, so let's play with that one. I haven't seen the specs for DoD, but let's use 50% for kicks and giggles (I am not well versed in lithium yet). 7kWh x 9 packs x 30 days a month x .5 DoD = 945kWh a month. That's maybe in the low to average usage range. $3000 x 9 = $27k, without the inverter(s) and solar. Let's pair that with a 10kW PV system, installed for $3/W, another $30k, to make the math easy, I'll throw in another $3k for the inverter or converter, assuming it needs something, totaling $60k for 945kWh a month. At $0.18 per kWh from the grid, that's $170 / month. That's 30 years ROI, except the batteries will not last 30 years, so there is no ROI without huge incentives. Unless saving the planet is considered a good return on investment ; )

I think there's nothing new about the announcement, except now there's a lot of marketing money and coolness factor put behind the old message of grid-tied battery backup solar systems.

[donald]

Or $3600 over the ten year warranty period.

So not good enough. But consider Hawaii without net metering.

I expect there are millions of homes and business worldwide where shifting 3 kwh from daytime peak solar to the evening produces a real value of $3/day average. The ROI in this case likely exceeds the cost of borrowing to install the system. Plus it likely improves grid stability in residential neighborhoods in places like Hawaii. Less excess during the day. Reduced evening demand.

Tesla needs net metering to go away for this pricing to work. But it should go away.

And has Sunking believed until 24 hours ago, it is not so much about the technology claims, but the warranty. When the ROI is good, and Tesla or Bosch will stand behind the product for the entire investment period, the purchase becomes a rational decision.

[Ian S]

A Trojan Industrial battery runs circles around it.

Please be more specific. Especially regarding parameters such as cycle life, warranty, cost, maintenance, size, weight, etc.

[Ian S]

Did anyone (who is open mined) run the numbers for peak shaving based on their electric rates? Maybe assume 2-3kwh used per day over ten years? The system probably breaks even in the $.20 -.30 range. It seems that in some markets the utility could finance the system with a positive cash flow to the owner.

Here in Phoenix under the existing APS demand rates for residential, every kW for the highest power peak in a "summer" month costs the customer ~$15. There are only about 20 non-holiday weekdays days in the month where the demand rate is operative. Assume the 7 kWh Tesla system can provide 4 kWh for peak shaving 20 days per month. That probably provides a reduction of ~3 kW in the power peak subject to the demand rate. That's a savings of about $45/month. Winter demand rates are less but I estimate you could save perhaps $30/month. Or $3600 over the ten year warranty period.

[J.P.M.]

Elon said the system would work 'out of the box' with existing solar setups... As there is no inverter that comes with the battery, is it safe to assume this battery would integrate then into an existing inverter? I'm no electrician and have only just yesterday signed papers for my solar PV system to be installed.. so forgive me if that is an ignorant question... I was just thinking of the Powerwall cost, plus installation, plus inverter.. the installation and inverter would cost almost as much as the battery.. UNLESS it could utilize the existing inverter...

Thanks!

I'd wait for the installs and see what develops rather than rely on what someone with skin in the game says. Maybe it's a great system, but saying so don't make it so. Time will tell.

[donald]

Elon said the system would work 'out of the box' with existing solar setups... As there is no inverter that comes with the battery, is it safe to assume this battery would integrate then into an existing inverter? I'm no electrician and have only just yesterday signed papers for my solar PV system to be installed.. so forgive me if that is an ignorant question... I was just thinking of the Powerwall cost, plus installation, plus inverter.. the installation and inverter would cost almost as much as the battery.. UNLESS it could utilize the existing inverter...

It doesn't need an inverter for the target home solar market. It needs a DC to DC converter apparently. Figure the average on grid solar install is going to take an electrician a half day. We know this system has a sophisticated control system. We know the 7kwh system is designed to instal to existing grid tie solar. It's unlikely there is a major hardware piece missing.
The 10 kwh system will probably frequently need substantial additional expense.

[J.P.M.]

Over the years I've sort of noticed a positive correlation between how early in game someone chooses to buy into a new technology and how much they actually know about that technology - early adoption, less subject knowledge. Same with other things like time shares or solar leases. In general, at least to my view, that is, more subject knowledge, later adoption is also usual and common.

[Stuntman]

Powerwall with existing solar

Elon said the system would work 'out of the box' with existing solar setups... As there is no inverter that comes with the battery, is it safe to assume this battery would integrate then into an existing inverter? I'm no electrician and have only just yesterday signed papers for my solar PV system to be installed.. so forgive me if that is an ignorant question... I was just thinking of the Powerwall cost, plus installation, plus inverter.. the installation and inverter would cost almost as much as the battery.. UNLESS it could utilize the existing inverter...

Thanks!