Micro inverters?????

Discussion in 'Off Grid Living' started by rsbhunter, Feb 5, 2012.

  1. rsbhunter

    rsbhunter Monkey+

    Ok, here is a prime example that a little bit of knowledge can be a dangerous thing!!! I looked at the "Enphase" micro inverters, and price wise, for just the inverters, they look comparable to , say, an OutBack FX3524 inverter...Now, i understand that the cabling and extras would be more $$$$, but IF, as explained, they work independently of each other, if one panel gets shaded, the others STILL are able to put out 100%. In other words , no anchor on the remaining panels.....Now, i realize that i haven't done alot of research yet, but what knowledge is out there about the pro's and con's of this new technology....Thanks for the limitless supply of knowledge AND patience you all have and share with us "newbie's" rsbhunter [applaud] P.S only time i will use an emoticon, promise...
  2. TnAndy

    TnAndy Senior Member Founding Member

    Yep....that's true, they operate independent with each panel. AND a case could be made for not having your inverter centralized.....if a single inverter goes, power stops....whereas losing just one micro inverter only takes out that panel/inverter.

    Here's the GREAT BIG --->BUT:

    Micro inverters are GRID TIE ONLY.....if the grid goes down, so does your ability to produce power. ( UL 1741 standard ).

    "Hybrid" inverters, like the GTFX3524 ( GT meaning it's a 3500w 24v inverter that meets UL 1741 and can be tied to the grid ) have two sets of contacts in them.....one ties to the grid, and opens if the grid goes down. When that happens, a second set of contact CLOSE, and allow you divert the power from the inverter to where ever you desire.....like a transfer switch, then to the house. That's the way I'm set up.

    Now, I've seen talk of mickey-mousing around grid tie inverters, and fooling them into thinking the grid is still up using another inverter/batteries to "simulate" the grid, but I don't know of anybody that has done it, and it would take some additional wiring, a transfer switch and such....so don't think you can easily fool them.

    Also, to run ANY system off grid, you simply MUST have batteries. It's not possible to run power off panels alone, there is no buffering if you try to draw more than the panels can supply, or if a cloud simply passes over head, and you "brown out" an appliance as the power drops off.

    SO, when building a system, you need to decide right from the GitGo....is this a grid tie only system to reduce my power costs, and payback is real issue with me.....


    Do I want power when the grid is down, ( or flat never want it hooked to me to start with )

    Because they are two very different critters.
  3. rsbhunter

    rsbhunter Monkey+


    I was wondering if there wasn't a catch...they all show to be 220V which didn't sound right with an off the grid system....to bad they werent made for off grid,,,,sounds like it could be a bonus to us who are either off grid, or planning to be, being grid tied is not an option for me...thats why i went to the guy's that know this stuff!!!!Thanks, rsbhunter
  4. TnAndy

    TnAndy Senior Member Founding Member

    Micro inverters are a real handy way to go with a grid tie only system......as I said, you don't have the issue of one main inverter taking down the whole system, and Enphase has a nice web based monitoring system so a glance at a screen tells you if they are all working, and what your production is, and has been. IF I were going grid tie only, I'd probably go with them.

    As to 220/240v, that's no problem for an off grid system either.....in the case of Outback, you simply use two inverters, one is wired as the "master" and the other as "slave" to phase the two 120v outputs opposite of each other, just like the power company does it. It also requires an Outback "Hub" controller to sync the inverters in the correct phase.

    Here is my setup, putting out true 240v. The Hub is the little black box mounted on the left side of the grey "Flexware" panel ( my AC output panel ).


    I probably wouldn't have gone with 240v, but my power company required a true 240v system to back feed to them.....the first system they allowed to connect was a 120v, and I think they had all kinds of problems metering it, so they said "no more of those"......which is fine.......now I have true 240v in case I do need it. I keep saying "true" 240v, because they do make transformers that bump up the 120v to 240v, and will work for some applications, but it's not "true" poly phase 240v...it's 240v that you still have to use a neutral on ( which you don't normally with "true" poly phase 240v )
    kellory and rsbhunter like this.
  5. rsbhunter

    rsbhunter Monkey+

    Micro inverters

    NICE SETUP!!!!! Were you a electrical engineer in a previous life? Or maybe the present one? When i set up my system i'll buy you a round trip ticket to Colorado so you can shake your head when i wire it wrong!!!!! Seriously though, that is a very professional looking set up....rsbhunter
  6. rsbhunter

    rsbhunter Monkey+


    Have to thank you for the heads up about the Amperage, more so than wattage being the critical parameter on the charge controllers....rsbhunter
  7. TnAndy

    TnAndy Senior Member Founding Member

    I don't fly, so save your money. If this country ever decides to get serious about air safety ( or safety in general ) and let's me pack on a flight, I'll go back to flying. Until then, if I can't drive or boat there, forget it.

    No, I'm not an EE, nor was I ever. I do have a State electrical license in TN, and have done a fair amount of residential and industrial wiring over the years, but this was a whole new ball game in solar. I even went and took a course to get NABCEPT certified ( solar installer ) after I put mine in, and then came back and made modifications to my screw-ups.

    If you'll buy that pre-built Outback power panel, honestly, there is nothing you can't be talked thru on the net. The hardest part is assembling the right components in the right order after you decide on panels, and they've taken all the mystery out of it with that pre-built board.

    Seriously, after I put that one in for a buddy, I'd NEVER go back, even doing it for myself....they are as close to "plug 'n play" as you're gonna get.
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