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Solar roof with wireless (dis)charging?

Discussion in 'Tesla Energy' started by Waiting4M3, Oct 29, 2016.

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  1. Waiting4M3

    Waiting4M3 Active Member

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    Can solar roof be built with induction coils under them to output electricity? reverse of wireless charging? This way a solar tile can be replaced as easily as a normal tile
     
  2. Johan

    Johan Took a TSLA bear test. Came back negative.

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  3. Ampster

    Ampster Member

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    Yes. Stand under some high voltage transmission lines some evening with a fluorescent tube. Watch the fllourescent tube glow and ask your self if you would want to live under that kind of power?

    It is possible but I for one would not be interested.
     
  4. brucet999

    brucet999 Active Member

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    No. Inductive chargers use AC current flowing through a coil to create a magnetic field that can induce AC current in another nearby coil. That induced current is then converted to DC in order to charge a battery. Alignment is crucial for efficiency and even in the best case resonant systems there is significant power loss.

    Solar cells generate DC current. The tiny currents generated by multiple cells are combined in a panel that delivers significant power. For home and commercial applications, the DC current from the panels is then converted by an inverter to 240V 60Hz AC power (in North America).
     
  5. Waiting4M3

    Waiting4M3 Active Member

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    #5 Waiting4M3, Oct 30, 2016
    Last edited: Oct 30, 2016
    It's my understanding the PV panels puts out <30V, so not sure about your concern
     
  6. Waiting4M3

    Waiting4M3 Active Member

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    OK, DC to AC is a missing link. But things like a micro inverter on per-panel level does exist. Solar micro-inverter - Wikipedia

    One idea here is that inverters basically work as a transformer, so the size (or number of loops) is scaled to the voltage you want. So if you want to design an inverter to go onto the grid, it needs to go to 240V, so there is a size constraint, but if you design a system that need not go to the grid directly, maybe to Powerwall, or to a Tesla central inverter, then the voltage spec is open to change, and the size can be smaller.
     
  7. deonb

    deonb Supporting Member

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    There is probably a way to make it work (inefficiently), but it's likely one of those things that you can hire someone to replace tiles 50 times before it makes up for the cost difference to have thousands of induction coils.
     
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  8. Ampster

    Ampster Member

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    My concern is not about the DC on my roof. My concern would be about an inductive charging system from my roof to my car.
     
  9. brucet999

    brucet999 Active Member

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    A transformer takes an input AC current and induces an AC current of greater or lower voltage in another circuit. An inverter takes a DC input and converts it to an AC output. Very different devices.

    Micro inverters cost about $150, not a huge cost for a 280W panel, but hugely expensive for a roof tile generating 1/40th of that output. Of course they would be smaller, but electronic device costs don't scale linearly, so the cost per watt on such a small micro inverter would have to be be several times higher.

    Then there is the maintenance problem. Inverters die by heat damage and their service life is generally about half that of the solar panels they serve. Micro inverters mounted on solar panels suffer more from heat, and their service life is generally less, than large wall mounted inverters. So now you are looking at locating and replacing dead micro inverters scattered all over your roof. So, instead of having to repair a few tiles because of some future damage occurrence, you guarantee that you will replace all of your solar roof tiles at least once during the course of 20 years.
     
  10. Waiting4M3

    Waiting4M3 Active Member

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    #10 Waiting4M3, Oct 30, 2016
    Last edited: Oct 30, 2016
    I was only referring to the connectivity of the solar tiles. Once the solar tiles are connected to a central switch, how that goes to the car is a separate compo
    The basic design of an inverter relies on coils, the structure is same as a transformer, what is added is a switch that changes the direction of the DC current. This switch used to be mechanical but now transistors and semiconductor switch can handle high current ratings, so the only bulky item in the inverter left are the coils, and their dimensions are fixed by the number of winding that scales with the voltage you want to get out of it. The coil is likely also the bulk of the cost since semiconductor is so cheap. I'm not saying it's easy off the shelf available component, but who knows, I want to see Tesla keeping pushing the envelope, maybe they figure something out here where everyone else is saying no way

    Power inverter - Wikipedia
     
  11. Ampster

    Ampster Member

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    I got the concept. Sometimes I hear radio actions in my dental fillings and there is no way I am going to put infection coils above my head. LOL
     
  12. brucet999

    brucet999 Active Member

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    I talked to a Solar City guy today. According to their briefing, each tile has small connectors at the top edge to which wires will connect leading to the next tile in the string or to a main line to the inverter.

    Roof penetrations (vents and stacks) get routed through special tiles with appropriate sized holes to fit a roof jack. Partial tiles (dummies, not active ones) for hips and valleys are cut using a water cooled diamond tile saw.
     
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