How to Switch Hardwired Ceiling fan from Grid to Off Grid Connection via switch

keepdoingkeepdoing Registered Users Posts: 4
BACKGROUND: I have a home with an unfinished basement. I am installing a substantial OFF-Grid system that will be dedicated 100% to this basement area. However, I am also going to wire the entire basement as an extension off my main Grid Panel (not connected to solar in any way - systems are COMPLETELY separate). I plan to basically Double-Wire the basement. For example.... If I want a wall socket by my bed - then I will basically run two SEPARATE circuits in and install 2 wall sockets - one labeled GRID, and the other labelled SOLAR. If I want a light to be powered from the grid, I plug it into the grid socket,a nd if I want to switch it to Solar, I just plug it into the Solar labeled socket. I have my reasons for this. I want every single outlet to be able to switch back and forth at will - so A SYSTEM WIDE TRANSFER SWITCH WILL NOT WORK. It will cost me a bit of money, but I am ok with that because it suits my needs for this project.

HERE IS MY PROBLEM / QUESTION: I am also going to have several things that are hard-wired. Ceiling Fans, the Blower on my whole house AC/Heat system, Sump Pump etc. Does anyone have a suggestion for the best way to be able to switch between the Solar and Grid circuitry on these hardwired systems. I' having a hard time communicating this concept to my electrician, who is I think being intentionally stubborn because he simply doesn't understand why I am wanting all this - which from my perspective is none of his business. Help?


  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    No idea how/if it fits with code, but maybe a double pole, double throw switch per circuit? Not sure about switching the neutrals.
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  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    Speaking as an electrican it's not a case of being stubborn, but rather a case of abiding by rules and regulations applicable to said trade, in order to accomplish a divided system, the two should be completely divorced, the grid system installed by a regular electrican, the solar by another person well versed in solar applications, the two should never be related to one another. This analogy is based on your assessment, but there are better ways to achieve grid/offgrid ballance by using available technology in the form of inverter chargers. No I'm not attempting to convince you to change your mind, but offering an alternative solution, in the form of grid assist, load shaving, battery  charging etcetera. Notwithstanding the fact that grid power can not be beaten on a cost per Kwh,  it would be wise to utilize grid whenever possible, not being judgemental, just pointing out reality. 
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  • BB.BB. Super Moderators, Administrators Posts: 32,800 admin
    You really need to look at making a switched (protected) sub panel. The sub panel is behind a transfer switch (manual/automatic/ac inverter automatic/relay etc.---Your choice).

    And you wire to the protected panel all of the (hardwired and other) that you want AC mains powered when grid is up and battery+inverter powered when the mains are down.

    I cannot think (off hand) of a handy wall switch like unit that you would want to install for ceiling lights/fans.

    In theory, Estragon's suggestion of a three way light switch could work... It just switches from system A 120 VAC hot to system B 120 VAC hot. And you have a second on/off/vari-speed-light switch for the overhead fan.

    I am not a big fan of this... You have the real question of how you wire up the AC neutrals from your main utility panel and from your AC inverter (sharing a common neutral to the point of use). PSW/TSW inverters are supposed to be isolated and should be able to live with a shared neutral--But I am not sure you could get a building inspector to buy off on this method--And I am not a fan of this either (sharing a common neutral between two or more concurrent power sources).

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  • MrM1MrM1 Registered Users Posts: 487 ✭✭✭✭
    edited July 2018 #5
    You might want to look at the multi- circuit transfer panels from Reliance Controls.  The ProTran 2 line might do what you want.  These panels can do transfers on a circuit by circuit bases.  Each circuit is controlled by a 3 position toggle switch (Grid / Off / Solar) and is breaker protected.  Simply substitute your inverter output for the generator output that the panel has on the label.   These panels mount about 18" from you main panel, but control whatever circuits you chose to run thru the ProTran 2.    And they are UL Listed and Code compliant (at least in the US)

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  • keepdoingkeepdoing Registered Users Posts: 4
    MrM1 - you win the prize for best answer!  Thanks!  That is exactly what I needed.  Just ordered one from Home Depot....

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