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Mini Solar Charger System to just Charge my Tesla S75D

Discussion in 'Model S: Battery & Charging' started by Joshib, May 11, 2018.

  1. Joshib

    Joshib Member

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    Even though my local utility charges about 10 cents per KWH, I am trying to see if I can install a small Solar Charging System with a storage setup so I can charge my car nightly to cover my 20to 30mile daily use. The storage could also provide backup in an emergency. Any ideas out there?
     
  2. pkodali

    pkodali Banned

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    Powerwall and a few panels
     
  3. David.85D

    David.85D Member

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    A 2 to 2.5 kW solar setup would work, depending on what you assume for average daily hours of useable sun. We average 4.5 hours here (average over the whole year). Do you want it to continue working on the shortest day of winter, or just an average day?

    30 miles range is about 10 KWh. One powerwall is 13.5 KWh nominal. Should need just one powerwall to store that much energy.
     
  4. robby

    robby Member

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    What is your goal in storing the energy yourself? It will likely be much cheaper to net meter, and it will also give you unlimited storage capacity in the grid rather than constraining you to a fixed size battery.
     
  5. The Duke

    The Duke Member

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    Run the numbers, I am betting using your Powerwall money on more panels is a better way to go with your utility as storage.
     
  6. eye.surgeon

    eye.surgeon Active Member

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    Yeah do the math, net metering is more financially efficient than a powerwall by a mile.
     
  7. BerTX

    BerTX Supporting Member

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    Net metering is not ubiquitous, and can be taken away at any time, depending on where you live.
     
  8. robby

    robby Member

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    This is true but for OP's reference, PA is among the states that require appointed utilities to allow net metering.
     
  9. BerTX

    BerTX Supporting Member

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    Hmm. The DSIRE website says this:
    "It is important to note that electric generation suppliers (EGSs) in Pennsylvania are permitted but not required to offer net metering."

    That was from 2017, so maybe it has changed.
     
  10. robby

    robby Member

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    My understanding is that ESGs are alternative suppliers you can opt into buying from. The next sentence gets at this ("Thus, customers who choose an electricity supplier other than their utility or Default Service Provider (DSP) must check with the supplier to see if it offers net metering service.") I think what they're saying is that appointed utilities must offer net metering, but if you make special arrangements with a third party provider, then net metering availability is between you and that third party.
     
    • Informative x 1
  11. ai4px

    ai4px Wes

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    Net metering is the key here... think the electrical grid as a big battery that you can push power into and get power of out. In my area, they keep a running balance of the excess on my account month by month and square up with me if there's excess at the end of each annum at wholesale rate for electric. Other regions however meter power such that what you put into the grid is credited to you at wholesale (4c/kwh typical) and *always* bill you at retail for power coming into you meter. This is common in Australia and probably in many places in the USA. Heck, my power company even keeps track of on/off peak for the power I sell them... not sure why, they'll give me the wholesale rate at the end of the year anyway.

    Without net metering the problem you'll have is that you need a way to store the power. How many kwh do you use to drive each day? You'll need a little more storage than that because unless you work nighshift, the solar system isnt making power when you are at home at night. SolarEdge makes an inverter called StorEdge that works with LG Chem 10kwh batteries. I've heard you can parallel two of them for 20kwh, not sure if you can parallel more. Never the less the StorEdge inverter is capped at 7.6kw. Given you probably get 5 hours a day, that's 38kwh potential... so a StorEdge with 4 LG Chem batteries would charge your car 1/2 way.
     
  12. AndreSF

    AndreSF Member

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    Not positive what the motivation here is... Cost savings? Your commute costs you around $1 - $1.3 in electricity per day. Makes little sense from cost-saving perspective IF system used only going to cover your charging needs. Having PV and PowerWall combo is more about self-powering your electrical needs IMO, while still using grid's elasticity as needed. And the obvious benefits of having a very capable Uninterruptable Power Supply (UPS) for the house.
     
  13. robby

    robby Member

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    Unfortunately the Powerwall isn't UPS grade recovery (I think transfer is rated around 1s). What you can do though is put a super cheap UPS behind each essential appliance in your house, rather than needing more expensive ones that can withstand a power outage.
     
    • Informative x 1
  14. BerTX

    BerTX Supporting Member

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    Thanks for the clarification. Obviously I didn't read it closely enough.
     
  15. gavine

    gavine Petrol Head turned EV Enthusiast

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    He said he wanted storage for emergency backup.
     
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  16. AndreSF

    AndreSF Member

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    Hmm, sure, I read that, but the primary listed OP goal was to cover 20 - 30 mile commute needs and backup was the secondary.
     

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