solar power and wiring

Discussion in 'General Electronics Chat' started by Sparky, Dec 1, 2010.

  1. Sparky

    Thread Starter AAC Fanatic!

    Aug 1, 2005

    I'm seeing programs that allow solar, wind and other types of power generation to be connected to your house (or business) and you are still connected to your grid. The power company meters both - what they provide to you and what your private generation provides.

    Your power company gives you a credit (or cash) for the difference.

    Technically - is there a problem or danger in having both connected (I know the power company would have it wired correctly I just don't see how yet)?

    Would or could the two sources "fight each other" or back-feed or something?

    The only wiring diagram I've seen so far is both sources end up at your breaker box.

    What if you are able to generate enough power on your own to meet your needs (or more than enough) - what keeps the power company's power happy and out of your house?

  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
    You use a grid tie inverter. $5k to $15k for just the inverter depending on size. Check with your power utility to see if they buy your electricity and for how much. Here in Ontario Canada it's called Microfit.
    A worthwhile setup will cost you tens of thousands of dollars.
  3. Sparky

    Thread Starter AAC Fanatic!

    Aug 1, 2005
    ok -

    let me now modify my original question -

    Can I get technical details on what the inverter does.

    I assume it will take teh DC from the cells and convert it to an approximated AC signal.

    How does it handle the in coming AC from the power grid along with the "approximated" AC from the solar cells?

    Can it give your house a little of both?

    Does it detect if the solar power is enough and shuts off the power grid's input?

    Can it put power on the grid if the cells are providing more than enough to the house?

    And so on ...?

  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    The inverter will monitor the power company voltage and will turn itself OFF if the power company line goes dead. You will no longer be able to sell or generate electricity. This applies to 'grid tied' inverters only.

    Battery powered inverters will disconnect from the grid by using a 'disconnect' switch. Cheaper set ups rely on you to throw the switch.

    Either way, internal circuitry monitors the grid and disconnects from the grid. If not, then your inverter would supply power to the grid when it goes down and anyone touching the lines(repairman) might get electrocuted. This is called 'islanding' and the circuit that disconnects you is called the 'anti-islanding' circuit.

    Google that term and you will get a lifetime of reading material on the subject.
  5. Sparky

    Thread Starter AAC Fanatic!

    Aug 1, 2005