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Tesla Powerwall 2

  • 01-09-2017 4:44pm
    #1
    Registered Users Posts: 12,068 ✭✭✭✭


    Nice review of the Powerwall 2 (13.5kWh battery) married to Solar PV.

    Can deliver 5kW continuous so decent enough for car charging. About €7k to buy just the Powerwall here, not to mind install and add Solar PV on top! :(



    This has to play a large part of the future once the price comes down. If it was priced right you might not even need a Feed In Tariff as you could just suck it all up in the battery and I hope it goes in that direction rather than only being viable with a FiT.
    Tagged:


«1

Comments

  • Registered Users Posts: 64,723 ✭✭✭✭unkel


    Nice but really doesn't make any economic sense at this moment. Best value is to use it on its own to suck up night rate and use it during the day. Say you have a big house and use about 5000kWh during day time hours (charge your car at night) and you would use the Powerwall to its full capacity every day.

    Than it saves you (15c - 6.7c) * 13.5kWh per day = a bit under €400 per year. That's the theoretical maximum benefit. Even if the Powerwall lasted for 20 years (7500 full cycles) with zero maintenance, you would just about break even. Or in other words - there are only 3 reasons for buying this right now:

    1. you already have solar and you have a huge overproduction that you can not use. Not even feed to grid for FIT or use to heat your water
    2. you want / need to be off-grid
    3. you just want to do it for the craic :D


  • Registered Users Posts: 1,460 ✭✭✭reboot


    I see from the film, that if the wall is retro fitted, ie bought on its own, without a solar PV installation, Vat in the UK will be at 20%, with oil and coal at 5%.


  • Registered Users Posts: 64,723 ✭✭✭✭unkel


    Oh. Watched the vid in full just now. You can't charge this with cheap night rate. Not yet anyway. I find that very peculiar. Wouldn't be very hard at all to implement and wouldn't cost much I'd have thought. Do the yanks not have cheaper night rates maybe, so they never thought of this?


  • Registered Users Posts: 1,028 ✭✭✭greglo23


    The reason it can’t use night-rate is safety. They haven’t figured out a 100% foolproof way to ensure that, in the case of a power-cut the Powerwall won’t feed
    volts back into the grid with repair crews working on it. Basically an electrical non-return valve that’s guaranteed to work on any and all grids worldwide.


  • Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 7,792 Mod ✭✭✭✭liamog


    Thats a good reason for not covering powercuts.

    It's an excuse which doesn't survive much investigation for time shifting, charging the battery on a timer set according to your night rates would not put anybody at risk.

    I'd say it's a technical gap instead of a regulatory problem. Knowing Tesla it's probably deliberate to reduce demand during the ramp up phase.


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  • Registered Users Posts: 1,456 ✭✭✭Evd-Burner


    I wonder what the cost and specs of units like this will be come 2020. If you could buy storage + 5kwhp for say 5k it would be a no brainer!


  • Registered Users Posts: 3,284 ✭✭✭cros13


    unkel wrote: »
    1. you already have solar and you have a huge overproduction that you can not use. Not even feed to grid for FIT or use to heat your water

    There is no FiT so by definition, if you have solar, you derive no benefit from exported power. Most domestic Solar PV installations in Ireland see most of their production in the middle of the day when nobody is home, and therefore in most installations of 2kW or more (~4kW would be a reasonable domestic install in the UK or NI for example) much if not most of the power is wasted by exporting it. If you have battery... you store that excess power and use it during the evening peak. ESB has been looking at a 3-tariff system for years (peak, daytime, night) and a home battery + 4kW solar would practically eliminate most people's use of the two higher-priced tariffs.


    greglo23 wrote: »
    The reason it can’t use night-rate is safety. They haven’t figured out a 100% foolproof way to ensure that, in the case of a power-cut the Powerwall won’t feed
    volts back into the grid with repair crews working on it. Basically an electrical non-return valve that’s guaranteed to work on any and all grids worldwide.

    Doesn't a G59 relay with islanding features do that?


  • Registered Users Posts: 64,723 ✭✭✭✭unkel


    cros13 wrote: »
    ESB has been looking at a 3-tariff system for years (peak, daytime, night)

    Or a lot smarter than that, tariff based on actual wholesale spot price. Load your battery up when the wind is blowing in the middle of the night for 1c/kWh :D


  • Registered Users Posts: 13,702 ✭✭✭✭BoatMad


    unkel wrote: »
    Or a lot smarter than that, tariff based on actual wholesale spot price. Load your battery up when the wind is blowing in the middle of the night for 1c/kWh :D

    ill beleive it when I see it

    "Our children will enjoy in their homes electrical energy too cheap to meter." - "Lewis Strauss, then chairman of the United States Atomic Energy Commission , in 1954"

    yeah , how'd that work out Lewis


  • Registered Users Posts: 223 ✭✭super_sweeney


    just came accross the video randomly and searched boards to see what people thought as I have panels on the roof which came with the house and just dont feel i get the most use out of them but dam these things are pricey


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  • Moderators, Society & Culture Moderators Posts: 38,402 Mod ✭✭✭✭Gumbo


    just came accross the video randomly and searched boards to see what people thought as I have panels on the roof which came with the house and just dont feel i get the most use out of them but dam these things are pricey

    Much cheaper alternatives available locally, just don't have the Tesla brand name.


  • Registered Users Posts: 1,744 ✭✭✭funnyname


    kceire wrote: »
    Much cheaper alternatives available locally, just don't have the Tesla brand name.

    What's the hybrid prime battery like in comparison?


  • Moderators, Society & Culture Moderators Posts: 38,402 Mod ✭✭✭✭Gumbo


    funnyname wrote: »
    What's the hybrid prime battery like in comparison?

    Not sure, the guys that installed my PV sell it, so id be interested in it myself long term.


  • Registered Users Posts: 12,068 ✭✭✭✭KCross


    funnyname wrote: »
    What's the hybrid prime battery like in comparison?

    Is it this one?
    http://primehybridenergy.com/downloads/pdf_residential_battery_integration.pdf

    Looks like a really small battery (5kWh) so not much use, imo.
    The spec also shows it being down to 80% capacity after 5yrs with an overall life span of 10years and 5yr warranty..... the stats don't look good to me.


    For comparison, the Powerwall has 13.5kWh usable, 10yr warranty.
    https://www.tesla.com/sites/default/files/pdfs/powerwall/Powerwall%202_AC_Datasheet_en_northamerica.pdf


  • Registered Users Posts: 3,284 ✭✭✭cros13


    Yup, nobody in the market can beat Tesla on price per kWh at the moment.

    Prime Hybrid Energy requires an external inverter (replacing your existing inverter, which is an additional cost) which is limited to putting out 3kW regardless of how many batteries you connect (so you can forget about running certain appliances or charging the car during a power cut).
    Each 5kWh battery block can only output between 2.32-2.85kW depending on state of charge.

    The powerwall has a built-in 5kW inverter capable of supplying up to 7kW for short periods. It allows the future upgrade path of adding up to 9 powerwalls for a total sustained discharge of 45kW.

    Only real competitor Tesla has is LG's RESU batteries, but they are pricier per kWh and you still need an islanding or battery capable inverter (budget €1-1.5k): https://www.mg-solar-shop.de/pv-battery-offgrid-systems/LG-Chem-Battery-strorage/

    It depends on what you want to accomplish, what your current and possible future PV array looks like and what your loads are.
    If you just want something cheap to reduce the amount of power exported to the grid for nothing in return Moixa are a good option: http://www.moixa.com/products/

    In practically every other residential scenario Tesla rules the roost. The big issue is getting a powerwall... there's a reservation list....


  • Registered Users Posts: 64,723 ✭✭✭✭unkel


    The big drawback of the powerwall is that is is fairly dumb. If only it could charge up at night rates and release during the day (so that in fact you'd only pay night rate for all your electricity needs), then it would start to make financial sense

    As of now, it makes no sense. It's an expensive toy for enthusiasts or people who have to live off grid.


  • Registered Users Posts: 12,068 ✭✭✭✭KCross


    unkel wrote: »
    The big drawback of the powerwall is that is is fairly dumb. If only it could charge up at night rates and release during the day (so that in fact you'd only pay night rate for all your electricity needs), then it would start to make financial sense

    As of now, it makes no sense. It's an expensive toy for enthusiasts or people who have to live off grid.

    From their website....
    "Time-of-Use Load Shifting
    If your utility offers a time-of-use rate plan, Powerwall can charge when rates are low and use that energy during expensive times to reduce your electricity bill. This feature will be available at a later date by an over-the-air update."

    Unfortunately "later date" can mean anything when it is spoken by Tesla! :)

    But Im sure they will and its good that they have the ability to remotely update it.


  • Registered Users Posts: 170 ✭✭al2009


    I was watching this episode of fully charged https://www.youtube.com/watch?v=VEh7V9_uIqM The company are offering power wall installed for 6500 in the uk, they aim to charge the powerwall at off peak rates, interesting concept.


  • Registered Users Posts: 1,014 ✭✭✭ei9go


    unkel wrote: »
    The big drawback of the powerwall is that is is fairly dumb. If only it could charge up at night rates and release during the day (so that in fact you'd only pay night rate for all your electricity needs), then it would start to make financial sense

    As of now, it makes no sense. It's an expensive toy for enthusiasts or people who have to live off grid.

    So the powerwall charges from the voltage from the solar panels so it's only a matter of a power supply to feed it at night. Can't be very difficult to rig up a 48V switched mode psu.


  • Registered Users Posts: 1,744 ✭✭✭funnyname


    al2009 wrote: »
    I was watching this episode of fully charged https://www.youtube.com/watch?v=VEh7V9_uIqM The company are offering power wall installed for 6500 in the uk, they aim to charge the powerwall at off peak rates, interesting concept.

    So is it a no brainer for the govt to subsidise the installation of powerwalls into every house in Ireland where possible. Say a 50% subsidy could generate 500k installations at the cost of €2bn but it would add 5000MW of storage to the network, easy peezy!


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  • Registered Users Posts: 170 ✭✭al2009


    From that site wave power could be the way forward, they are producing 2Mw units which can be harnessed together, solar is also becoming very attractive after seeing what they do there. A truly smart grid is not impossible and very achievable.


  • Posts: 21,179 ✭✭✭✭ [Deleted User]


    At 7 cent per Kwh night rate and 17 cent day it makes no sense to install solar PV or install backup batteries.

    Only thing that makes sense is a feed-in-tariff , that's not happening.

    No grant for solar PV or wind micro generation and I bet if there was it would drive up the cost of installations.


  • Registered Users Posts: 64,723 ✭✭✭✭unkel


    At 7 cent per Kwh night rate and 17 cent day it makes no sense to install solar PV

    Indeed. I've just installed a 750W Solar PV system today :D

    At a fraction of the price installers are looking for though. My payback period is about 5-6 years. The solar PV system the ESB are offering has a payback period of at least 40 years...


  • Registered Users Posts: 12,068 ✭✭✭✭KCross


    unkel wrote: »
    Indeed. I've just installed a 750W Solar PV system today :D

    Whats involved? What did you have to buy?

    Were you able to do it yourself or did you just buy the bits and get a spark in to connect it up?

    What happens with any excess?

    EDIT: Its a bit OT... maybe you should start a new thread and tell us all! :)


  • Registered Users Posts: 64,723 ✭✭✭✭unkel


    Got an inverter on eBay for a fraction of what they normally go for, got 3 end of line panels for a bit more than half of what they normally go for. All the stuff is click and play, 100% waterproof. Had to make one cable myself, but was pretty easy to do. Used dedicated mounting system for PV panels and spend a few hours this afternoon with a lot of help from my neighbour, putting it up on the shed. Total spend just over €500. I guess the 3 bottles of good wine I gave him will add a few months to my payback period :p

    And I will use all of the output at full daytime rates as it is for a high electricity consuming hobby that needs about 850W 24/7, so no feeding back to the grid.


  • Registered Users Posts: 64,723 ✭✭✭✭unkel


    Was actually pretty amazed this morning that I saw 400W being produced from my test setup of 2 panels leaning on the wall of my house (maximum output 500W). It's the middle of winter!


  • Registered Users Posts: 12,068 ✭✭✭✭KCross


    unkel wrote: »
    Got an inverter on eBay for a fraction of what they normally go for, got 3 end of line panels for a bit more than half of what they normally go for. All the stuff is click and play, 100% waterproof. Had to make one cable myself, but was pretty easy to do. Used dedicated mounting system for PV panels and spend a few hours this afternoon with a lot of help from my neighbour, putting it up on the shed. Total spend just over €500. I guess the 3 bottles of good wine I gave him will add a few months to my payback period :p

    And I will use all of the output at full daytime rates as it is for a high electricity consuming hobby that needs about 850W 24/7, so no feeding back to the grid.

    But do you not need a spark to connect it to your distribution board?
    Or is it independent to your house supply?


  • Registered Users Posts: 64,723 ✭✭✭✭unkel


    Nope, inverter plugs into any power socket with the standard UK 3-pin plug


  • Registered Users Posts: 1,931 ✭✭✭ewj1978


    wait wut? your feeding into your home supply from a 3 pin plug?

    whats your expected output per day?
    what size were the panels?


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  • Registered Users Posts: 12,068 ✭✭✭✭KCross


    unkel wrote: »
    Nope, inverter plugs into any power socket with the standard UK 3-pin plug

    Interesting, so what would happen the excess if you didn't happen to have enough background load?

    I didn't realise it was that simple to setup.


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