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Thread: "Power Wall"?

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    Great Pumpkin NutmegCT's Avatar
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    "Power Wall"?

    Lots of positive comments on the 'net about the Tesla Power Wall. Quality material, stores electrical power. But I can't find any comments on long-term use, other than things like "when the power went out for a few minutes we didn't even notice."

    Question: If the grid goes down and you rely on the Power Wall for your house ... how long does the Power Wall supply power?

    At $7800 for the PowerWall 2, plus $1000 for the hardware needed, plus est. $2K for installation, you're talking $10K. That's not even considering the cost of a solar panel setup.

    Sure can't find any charts or tables on this other than "The PowerWall 2 can supply power for one or two hours", with no detail on the current draw used.

    I'm thinking that, except for short "power blips", a standby generator is probably more worthwhile (unlimited power as long as it's fueled up).

    What say ye all?
    Mac & Phyllis Take a Trip: http://nutmegflyer.com/trip-details-daily-updates/
    History: 1976 MGB, 1959 Triumph TR3A, 1960 Mercedes-Benz 190b, 1958 Rambler American.
    Current: 1953 MG TD27318.

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    Yoda John Turney's Avatar
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    Re: "Power Wall"?

    I have a friend that has one. In addition to supplying power if the grid goes down, it supplies power to him at night, so he doesn't have to pay utility prices.

    Have you seen this datasheet? https://www.tesla.com/sites/default/...rthamerica.pdf

    How long it will supply power depends on how much load you have. Usable power is 13.5 kWh. Simplifying, if you are drawing 1 kW (ten 100-Watt lightbulbs), it will last 13 1/2 hours. If you draw 2 kW, it will last half that time.

    If we think the grid is down for any length of time, we will hook up the freezer, refrigerator a few lights and my wife's computer (don't ask) and plug into the RV generator.
    John, BN4

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    Great Pumpkin NutmegCT's Avatar
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    Re: "Power Wall"?

    Thanks John. When I run my home generator (3.5K continuous), it's really loaded with just the refrigerator and well pump, and a few lights and the TV. I have to shut off the refrigerator or well pump to run the microwave. That makes me think I'd pull at least 3.5K from the PowerWall.

    Thus, a 13.5 kWh usable from the PowerWall would last just under 4 hours, then be useless (altho' I have to keep in mind that refrigerator and well pump run as needed, not continually).

    This gets me to thinking my emergency generator (cost me $600 several years ago, runs fine) is a heck of a lot more cost efficient, and the PowerWall would be an expensive "don't notice the power blips" device.

    Tom M.
    Mac & Phyllis Take a Trip: http://nutmegflyer.com/trip-details-daily-updates/
    History: 1976 MGB, 1959 Triumph TR3A, 1960 Mercedes-Benz 190b, 1958 Rambler American.
    Current: 1953 MG TD27318.

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    Re: "Power Wall"?

    Side note: I wanted to use the Thanks icon on John's post, but when I clicked it, I got:

    [] operator not supported for strings on line 182 in /home/bcf/public_html/bcf/includes/functions_post_thanks.php
    #0 /home/bcf/public_html/bcf/includes/functions_post_thanks.php(137): fetch_thanks('1120562', '', false)
    #1 /home/bcf/public_html/bcf/post_thanks.php(64): thanked_already(Array)
    #2 {main}

    Ain't computers great!

    Mac & Phyllis Take a Trip: http://nutmegflyer.com/trip-details-daily-updates/
    History: 1976 MGB, 1959 Triumph TR3A, 1960 Mercedes-Benz 190b, 1958 Rambler American.
    Current: 1953 MG TD27318.

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    Re: "Power Wall"?

    Seems to me there's something wrong with this picture. 3.5kW is quite a bit of power, roughly 3.5 horsepower. Well pumps vary no doubt, but I can't imagine it's more than 1hp. ISTR mine is 1/4hp. Refrigerators are usually quite a bit less than 1 hp. And as you mentioned, they shouldn't run continuously. Microwaves typically draw quite a bit (close to 1kW unless it's a built-in), but normally only run for a few seconds at a time. That leaves "a few" lights ... have you considered LEDs?

    Gen set ratings tend to be way optimistic, IMO, if not downright deceptive. I was looking at one just the other day, that says "3500" in big letters across the top, but is actually rated 2kW continuous output. I've never actually run it, but at some point I'll have to try it out and see what it will actually do.

    But I'll agree, if you're happy with your gen set, there's little reason to upgrade to battery power. I like battery for my computers (so minor blips don't cause lost time and work), but everything else can wait.

    Quote Originally Posted by NutmegCT View Post
    Thanks John. When I run my home generator (3.5K continuous), it's really loaded with just the refrigerator and well pump, and a few lights and the TV. I have to shut off the refrigerator or well pump to run the microwave. That makes me think I'd pull at least 3.5K from the PowerWall.

    Thus, a 13.5 kWh usable from the PowerWall would last just under 4 hours, then be useless (altho' I have to keep in mind that refrigerator and well pump run as needed, not continually).

    This gets me to thinking my emergency generator (cost me $600 several years ago, runs fine) is a heck of a lot more cost efficient, and the PowerWall would be an expensive "don't notice the power blips" device.

    Tom M.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Re: "Power Wall"?

    Thanks Randall. I think calculating the max draw of my appliances on the source (PowerWall or generator) is beyond my brain cells. Certainly easy for constant draw (lights, etc.), but not for things that oscillate on/off.

    I know my well pump is 1/2 hp, 230 volts, runs only after I've drawn a couple gallons of water. Refrigerator is rated 683 kWh "per year" (whatever that means). Fortunately I can heat the whole house with the oil burner / hydronic system, 120 volts, 2 amps.

    But I do know that when the generator (4kW max, 3.5kW continuous) is running smoothly, the well pump slows it down noticeably, as does the refrigerator. Adding the microwave (1kW) dims the lights considerably, the generator gets *very* loaded, and slows.

    Tom M.
    Mac & Phyllis Take a Trip: http://nutmegflyer.com/trip-details-daily-updates/
    History: 1976 MGB, 1959 Triumph TR3A, 1960 Mercedes-Benz 190b, 1958 Rambler American.
    Current: 1953 MG TD27318.

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    Re: "Power Wall"?

    Is the cable you are connecting the generator to your house heavy enough to carry the load?

    David
    TR3A TS75524L

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    Re: "Power Wall"?

    Quote Originally Posted by NutmegCT View Post
    Refrigerator is rated 683 kWh "per year" (whatever that means).
    That is an overall average power consumption, based on "average" usage, so it takes into account the compressor not running full time (and obviously makes assumptions on how often you open the door, how warm the room is and so on).

    24 hours/day times 365 days/year is 8760 hours per year. So in theory, your refrigerator consumes an average of 683,000/8760 = 78 watts.

    As they say, your mileage may vary.
    Randall
    56 TR3 TS13571L once and future daily driver
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    Re: "Power Wall"?

    We installed a 20kw Generac automatic system which runs off our propane supply. Tested with every electrical device (full electrical house) on our property turned on and where applicable set on it's highest power usage, this also included my shop compressor, the electrician said the system wasn't even under a strain at any point. Cost, $5,000 total. It sets 150 feet from the house and works perfectly. If the grid goes down, 15 seconds later it starts automatically. I would never be without one again. $10,000 bucks is a little pricey, especially for a battery type system, the Tesla name doesn't impress me either, our generator ran once 24 hrs a day for 3 1/2 days non stop and performed flawlessly.
    s-l1000.jpg

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    Re: "Power Wall"?

    I have a Lincoln Ranger 8 as a back up generator which I got about 20 years ago. I have had to rely on it about 4 times in the 20 years. For a 6 days after one hurricane. It will run the fridge and freezer, well pump, microwave, lights and outlets to charge batteries and the gas tankless water heater. At that it is never under full load.
    It cost less than $2000.00 and is also a welder.
    Wired through a manual interlocked transfer switch to the sub panel.

    David
    TR3A TS75524L

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    Re: "Power Wall"?

    Thanks gentlemen. David - what is the max wattage rating, and the continuous wattage rating, of your Lincoln 8?

    Thanks.
    Tom M.
    PS - just checked my refrigerator using a watt meter: 160 watts when running.
    Mac & Phyllis Take a Trip: http://nutmegflyer.com/trip-details-daily-updates/
    History: 1976 MGB, 1959 Triumph TR3A, 1960 Mercedes-Benz 190b, 1958 Rambler American.
    Current: 1953 MG TD27318.

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    Darth Vader
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    Re: "Power Wall"?

    8000 watts continuous.

    I got the transfer switch from Northern tool.

    DavidRanger 8.jpg
    Fuse box.jpg
    TR3A TS75524L

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    Re: "Power Wall"?

    The notes on the fuse box were there just in case I was out of town and someone unfamiliar with the setup needed to run the system.

    David
    TR3A TS75524L

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    Great Pumpkin NutmegCT's Avatar
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    Re: "Power Wall"?

    Thanks David. I think my next step is to figure why my 3500 watt generator slows so much when several consumers are running.

    Tom M.
    Mac & Phyllis Take a Trip: http://nutmegflyer.com/trip-details-daily-updates/
    History: 1976 MGB, 1959 Triumph TR3A, 1960 Mercedes-Benz 190b, 1958 Rambler American.
    Current: 1953 MG TD27318.

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    Re: "Power Wall"?

    The next big thing for solar is the inverters about to be marketed by Enphase.
    They allow power to be made when the grid is shut off
    Don
    "Stick a Wedge in it!"
    Mount Pleasant,SC

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    Re: "Power Wall"?

    A number of years ago (after using the portable gasoline Craftsman unit for 10) we installed a Kohler.
    Kohler 12RES generator, at rated 12KW (derated on NG) through a RDT-CFNA-0200A ATS switch.

    Automatic, runs as long as there is natural gas, I guess.

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    Re: "Power Wall"?

    A friend just had a Generac system installed. He had to have a LPG tank installed as well as he was not on natural gas. His wife did not want the "Ugly" tank in the yard close to the house so he had it buried as far away from the house as he could get.
    Total cost for the tank, hole and pipe added $10,000.00 to his cost if installation.

    David
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    Re: "Power Wall"?

    You can buy a lot of ugly for 10K
    Don
    "Stick a Wedge in it!"
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    Re: "Power Wall"?

    He took money out of his 401K account to do this essential upgrade???

    David
    TR3A TS75524L

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    Administrator Basil's Avatar
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    Re: "Power Wall"?

    Quote Originally Posted by NutmegCT View Post
    Side note: I wanted to use the Thanks icon on John's post, but when I clicked it, I got:

    [] operator not supported for strings on line 182 in /home/bcf/public_html/bcf/includes/functions_post_thanks.php
    #0 /home/bcf/public_html/bcf/includes/functions_post_thanks.php(137): fetch_thanks('1120562', '', false)
    #1 /home/bcf/public_html/bcf/post_thanks.php(64): thanked_already(Array)
    #2 {main}

    Ain't computers great!

    Another user had the same issue (probably many did but didn't say anything about it). Here is the reply I made to the him:

    Well, I think you just found an issue with a newer version of PHP I recently upgraded to for the forum. PHP is the script language that basically handles all the behind the scenes actions for anything that you do on the forum. (For example, even reading this thread/post, if you look up in the address bar you will see it is using a script called "show thread.php" and PHP is the "language" that interprets all the commands in that script. This forum software was developed back when version 5.6 (or maybe older) was the latest version. There have been many updates to PHP since then. I recently updated the PHP version running on this site to version 7.1, which is not the latest, but is supposed to be the newest that this forum software will run on. While it seems that basic forum is running ok on 7.1, that "thank you" feature is not stock forum software, but rather a 3rd party plugin to "add: that capability to the forum. Apparently, that plugin doesn't like version 7.1. I just backed off one version to 7.0 and the thanks button seems to be working. Try it now and see of it works for you.


    PS: When you notice
    weird problems like that, please post in the Forum Help section or PM me to let me know there is an issue.

    Basil

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