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  • Tesla Powerwall 2

    Hi folks,

    2 days ago, Tesla announced the Powerwall 2. The specs are pretty nice: 14 KWh, integrated inverter, 10 years warranty - for 5,500 US$.

    I know that message thread will get heated, but what is opinion on that thing?

    Thanks!

  • #2
    Getting better, but that's still only about 300AH

    Comment


    • #3
      Quick back of the envelope lifetime costs, assuming that the battery lasts exactly the warranty length (10 years) and that the $5500 is the price to consumers:

      5500/(365.25*10) = $1.50/day

      Assuming 25% DoD average over life of the battery (3.5 kWh/day): 5500/(365.25*10)/3.5 = $0.43/kWh
      50% DoD average (7 kWh/day): 5500/(365.25*10)/7 = $0.215/kWh
      75% DoD average (10.5 kWh/day): 5500/(365.25*10)/10.5 = $0.143/kWh

      Comment


      • #4
        Originally posted by Logan5 View Post
        Getting better, but that's still only about 300AH
        AH is not a particularly appropriate measure for storage capacity of a battery bank if the system voltage is not specified. Useful for comparison only if the nominal voltage of PowerWall 1 and 2 are the same.
        SunnyBoy 3000 US, 18 BP Solar 175B panels.

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        • #5
          That is some funny stuff. I don;t care who you are. AH mean nothing. Absolutely nothing.
          MSEE, PE

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          • #6
            Right now, vaporware for the average consumer, despite the recent introduction on a film set.

            To me, the Tesla products are the Duesenberg's of the past, when what was demonstrated by Henry Ford was that if you want to revolutionize the world (in his case forcing the change from limited electric to fossil fuel), the Model-T for the average consumer is what is needed for the revolution from Tesla.

            I must give him credit to his namesake though - the remote-controlled boat wasn't so far fetched now that we have autonomous S-models.

            Comment


            • #7
              What I find funny is that they want a $500 deposit per powerwall without describing anything about how it would work with an existing system. Sure - let me just hand you some money for your vaporware so you have some additional working capital. Also funny is how they estimate it based on number of bedrooms - you know - because bedrooms are such heavy users of power in most homes

              Comment


              • #8
                I'm really glad someone else started this thread, so I can merely comment rather than start a whole new one myself.

                I am building a new house in a semi-rural area in the Columbia River Gorge. The winters can be harsh, so I have been advised to plan for occasional power outages that might last as long as a week. This is in a 2,000-square mile county with 21,000 people. Not poor, but not rich, and prone to nasty ice storms and the occasional foot of snow. Self-reliance is still a necessity. Rather than rely on the sheriff, have guns. Rather than rely on the utility crew, have a generator. I've investigated solar panels, and the preliminary caluclations look promising. Now: Grid-tie with generator, or off the grid with battery?

                The average house in that area uses 1,400 kWh/month according to the local utility. Which is 325 kWh a week. Tesla's new Power Wall stores 14 kWh. As the owner of an electric car (long story), I know that lithium batteries hate to be drawn down below 20% state of charge. Yep, you can do it, but do it very often and you KILL the battery life. So that 14 kWh should be called 11.5 kWh of usable capacity. To run the house for a week, we'd need 25 batteries. At $5.500 a pop, that's $137,500.

                Sorry, Elon Musk, but I think I'll go get myself a Generac. I'm going to have a big ol' propane tank or two anyway, to run the backup furnace, the kitchen range, the water heater, and the fireplace. $10K vs. $137.5K? May I suggest that you concentrate on making sales to rich, stupid, smug California eco-yuppies, not to put too fine a point on it? You're welcome. By the way, your new Model X goes for $140K, and I understand that them gull-wing doors don't work so well. I got my EV for $8,500 after the tax credit. My mother didn't raise a California fool.
                Last edited by Charlie W; 11-02-2016, 12:32 AM.

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                • gmanInPA
                  gmanInPA commented
                  Editing a comment
                  Batteries make _can_ sense in a few situations, but not as many as most imagine they would. If your reasons are green (as in money or environment), fuggedaboudit.

                  I've outlined some of what I feel are legit reasons for batteries in this thread: https://www.solarpaneltalk.com/forum...with-batteries

                  One of the posts there includes a flow chart I put together to outline something of the decision-making process that one might use to consider batteries vs generator & batteries, etc.

                  You just had to mention to solar roof tiles, didn't you Sounds like a nice idea, but I can't imagine installation would be very easy or practical. I'd be interested to see how the circuits are wired from those tiles, etc. For me, I'd rather just have my panels separate from a good quality roof. Kinda like heat-pump hot water tanks... by consolidating, you just make it more costly when one or the other fails.

                • Charlie W
                  Charlie W commented
                  Editing a comment
                  Solar roof tiles. Oh boy. No, I don't think I'll go there. I will only get nasty. Or nastier, as the case may be.

                • Guest's Avatar
                  Guest commented
                  Editing a comment
                  Anyone have information how they are assembled. Do you have to solder them on the roof the cells together. Probably Click and play easy to install assembly. I doubt its performace would be as efficent as regular solar panel. but its has cosmetic features that would appeal to expensive home buyers market.

              • #9
                10 year warranty is really low.

                Comment


                • #10
                  Originally posted by Charlie W View Post
                  I'm really glad someone else started this thread, so I can merely comment rather than start a whole new one myself.

                  The average house in that area uses 1,400 kWh/month according to the local utility. Which is 325 kWh a week. Tesla's new Power Wall stores 14 kWh. As the owner of an electric car (long story), I know that lithium batteries hate to be drawn down below 20% state of charge. Yep, you can do it, but do it very often and you KILL the battery life. So that 14 kWh should be called 11.5 kWh of usable capacity. To run the house for a week, we'd need 25 batteries. At $5.500 a pop, that's $137,500.
                  Heating your house with batteries will never work - forget about it, take that idea out of your head. If you want to go off-grid and you need heating during winter, look for alternate heating sources like a wood chips/pellets furnace with radiant floors and others.

                  Converting electricity into heat is a very inefficient process.


                  Comment


                  • #11
                    Howdy All,

                    I found this article today and thought I would post it, cheers.

                    http://seekingalpha.com/article/4017...t-hurt-enphase

                    Comment


                    • #12
                      Originally posted by solar pete View Post
                      Howdy All,

                      I found this article today and thought I would post it, cheers.

                      http://seekingalpha.com/article/4017...t-hurt-enphase
                      I suspect Tesla has the Powerwall product to utilize spare manufacturing capacity in their so-called gigafactory. Then they can "sell" these things to their Solar City partner. If the merger goes through, it'd be an internal transfer, and they could heavily discount 'em. Makes for an interesting accounting question or three. Given the cost and limited (to put it mildly) genuine market, I find it really hard to take the Powerwall as a genuine stand-alone product in its own right.

                      Comment


                      • #13
                        From a stand-alone concept, does it *require* internet access during the uptimes of non-use for remote monitoring, data collection and such?

                        And if so, what security steps have been taken in that regard? Does the consumer provide his own router (typically a cheap unsecure piece of junk)....

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                        • #14
                          Capacity quote is 13.8Kwh and Li-Ion is still not that efficient

                          Comment


                          • #15
                            Originally posted by justpower View Post
                            Capacity quote is 13.8Kwh and Li-Ion is still not that efficient
                            What makes Li-ion "not efficient" ?? explain.

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