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Solar Charging an EV

Discussion in 'Technical' started by Supercaliber64, Aug 20, 2010.

  1. Supercaliber64

    Supercaliber64 New Member

    Aug 6, 2010
    South Lyon, MI
    reposting from Energy and Environment
    Looking into adding solar panels to power my home. With all of the talk about the impact of EV on the utility grid, it would make since to expand the capacity to have enough energy to charge an EV.

    Does anyone have an idea how and what size of a system I would need to charge an EV?
    1Kw, 5Kw, etc
    Battery switch so that it charges during the day or can the energy be stored and charge my EV battery at night?

    Thanks for your insight.
  2. SByer

    SByer '08 #383

    Oct 23, 2007
    Cupertino, CA
    Treat the grid as one big battery. There's more than enough nighttime excess capacity to handle charging all the EVs that will end up in the marketplace over the next 20 years (and probably more - estimates are that it takes off-the-grid electricity to pump and refine a gallon of gas as an EV needs to go 30 miles - EVs are likely a net wash on the entire grid). A Roadster lets you set up charging start to any time you want (by location), and I'd be shocked if all EVs going forward don't let you do that.

    As for panel count, your installer can give you an estimate of the average kWh per panel in your location. Use 350Wh/mi as a good first-order approximation of EV usage (including charging losses). Multiply and divide as per the units. Depending on how much you drive and location, it should end up in the 5-12 panel range.

    For example, our 41-panel (SunPower 225s) system got us 11593 kWh over the past year, or 282kWh/panel/yr. I put on about 5000 mi/yr * 350Wh/mi / 1000 = 1750kWh/yr. That means about 6.2 of the panels we have cover my driving.
  3. VintageGuy

    VintageGuy New Member

    Sep 15, 2010
    Hey Supercaliber64,

    The batteries we used at Auto Parts Los Angeles need around 6-7 kwh of electricity for a half charge, and it usaually takes 7.3 kw solar power system to generate more than enough power to run our house and pool pump, recharge the car, and export the excess back to the grid. maybe this should also apply to you. But different types of batteries result to some variations.

    Know the battery type and its capacity to store energy to make everything work well.. Cheers! Lets go For Green Environment ey! :cool:

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