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Help me understand Powerwall2 use case

Discussion in 'Tesla Energy' started by masam, Jun 9, 2017.

  1. miimura

    miimura Active Member

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    I don't think that residential presents much of an opportunity for attracting load during the mid-morning period. Policies to encourage workplace EV charging and commercial real-time cost following rates present a much clearer opportunity to attract variable loads.

    If it became more cost effective for businesses to install enough EV charging points so that cars could be left connected and charged variably throughout the entire workday, the variable load could have a meaningful impact on grid balance and renewable curtailment.
     
  2. bonaire

    bonaire Active Member

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    You have to do the math on # of powerwalls based on house size, electric usage, how many days of clouds you may get and so on. Just one powerwall may not be enough for larger homes with power-hungry families. They can be stacked in place or lined-up along a wall or floor.
     
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  3. gavine

    gavine Petrol Head turned EV Enthusiast

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    True, but not necessarily for back up purposes, unless you want full 100% usage during extended outages or if you want to go off-grid. Most people don't get generators to support the entire house...just critical loads. The key thing here is that the Powerwall allows you to use you solar during an outage so you can now have more kW of power available than just what the Powerwall puts-out, at least while the sun is shining.
     
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  4. Lloyd

    Lloyd Well-Known Member

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    You can supply specific circuits with a powerwall and solar during an outage, but not the entire house!
     
  5. bonaire

    bonaire Active Member

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    Right- the configuration depends on needs and wants. The main issue is someone thinking they only need "one" PW2.0 may need to size-up the system depending on their overall demand profile. Might need two or more if wanting long-term outage coverage through cloudy periods (such as during a snowstorm or similar). Old hybrid systems used a generator as backup to maintain battery charge levels. Not needed as much anymore but could be part of a larger home's complex standby system.

    When shopping for a fossil fuel generator from Generac, a lot of thinking goes into the standby circuit setup and if the customers want whole-house or selecting certain managed circuits. For a few bucks more, you can go whole house - maybe 5% more price versus adding extra electrician work to set up a second standby circuit board and extra wiring or using their somewhat pricey managed circuit breakers.

    The Solar Edge system with a solar array is a good way to replace Generac as standby circuits. Of course, as a standby system, it wouldn't qualify for the 30% Federal Tax Credits (and people shouldn't take the credit if using it as standby).
     
  6. Ampster

    Ampster Active Member

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    The credit depends on how you charge it. A Powerwall could actually serve several purposes although one might need to have a charging discharging strategy if one wanted it to serve as a backup as well. For example you might limit the discharge so that you always had some kWhrs as a reserve.
     
  7. bonaire

    bonaire Active Member

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    IRS won't check, do whatever suits you. I was just saying if a battery is installed for the express purpose of backup power, and lets say you charge it in May once off solar and wait for a standby event of two hours in December, one should not take a 30% tax credit for that.
     

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