Monday, July 1, 2024

Solar Power Question

I was a,software engineer not an electrical engineer.   My impression is thst some inverters will allow to plug the output into an outlet in your current house.  This power gets distributed to every wire on the same circuit breaker.  Is thst correct?

Grid-tie inverter seems to be the solution.  This isolates you from the grid as needed.


  1. DO NOT DO THAT!!!!!!! If you do, inverter power goes to EVERY connected wire on the circuit, Half the circuits in the house, and will try and power the whole neighborhood. If a lineman is working on repairs you will energize the circuits to full voltage and possibly kill them.

    All battery-backed solar power and emergency generator systems include a house disconnect that isolates a house from the grid before connecting to the generator to power the loads inside.

  2. Possible, but not up to code.

    If you're going to connect an inverter and/or a generator to your house wiring, you need to do it in such a way so that the inverter can never be connected to rest of the grid, or your risk shocking any power company workers. (Even a minor shock can cause someone to fall off a ladder.) This calls for a transfer switch. For larger generators or inverters, you can get automatic switches that disconnect the house from the grid, before connecting the inverter and/or starting the generator.

    I don't know that anyone has been killed, but the power companies tend to worry about this a lot. (I forget where, but it was prominently displayed in some info about "power after a storm." Probably Florida)

    If you want to connect an inverter permanently to the grid (grid tie or hybrid - with batteries) the requirements are even more arcane.

    All of the solar power companies - the bigger ones anyway like MidNite Solar - should have the equipment on the websites.

  3. Sorta, depending.
    If 120V then you can power an entire 120 v circuit leg (breaker) using a suicide type plug from the inverter just as you would from a generator. (not a good idea or very safe at all. ).

    I think that is what you are asking; If not, email me and I will try to explain better once we have narrowed down the question.

  4. The "Plug and Play" easy grid tie converters are not (just) a suicide cord on an inverter 120v output. They sense the incoming voltage from the power company both to synchronize with it and to auto 'island' the system (i.e.: for this tech that means shut down the inverter output) should power-company power disappear.
    For safety, they also don't put any current into the wrong-way plug if there isn''t mains voltage present already on it.
    Most US residential electricity comes into the home as two 120v "legs" at opposite polarity, netting 240v for large appliances. Providing an extra power input via one standard outlet is going to provide power to that circuit and also to all the other circuits that are on the same "leg" of the breaker-box.

    Presumably if it has a NEMA 5-15 plug and is approved by a NRTL certification lab, the output is limited to 15A for all circuits thus powered -- but the any excess is going to be provided by the power-company anyway.

  5. See for one example

  6. If you're considering connecting any kind of generating equipment to your household electrical system, you MUST have a transfer switch at your breaker box. Otherwise when the power goes out, you could end up back-feeding the grid including through the transformers and risk injuring or killing the linemen trying to restore power who thought the lines were dead.

    Now technically, you could do it just but killing the main breaker, or if you're trying to stick to one circuit, just that circuit's breaker, but it's a big risk. And the home center will NOT sell you an adapter cable that has a male plug on each end.

  7. Yes. I'm a civil engineer, not an inverter engineer. But if you backfeed power into an outlet (dangerous and likely illegal), everything connected to it will have power. That means you should switch off your breakers first, so it doesn't backfeed through the individual branch circuit breaker to the main power input in your breaker box, which then allows current to backfeed into not only all the other branch circuits, but also back outside, up the pole, and out to the poor guy working on your power outage. I would kill ALL the breakers for such an attempt.

    Alternately, and better, you can install a manual lockout device in your breaker box along with a couple of new breakers and a receptacle for alternate power input. You can do it yourself very reasonably if you have the ability to run a wire to a new receptacle. It acts like a poor man's transfer switch by allowing either the power company power, or your own generated power to feed into your house as a power source, but never both at the same time. Look it up on youtube.