"Plug and play" grid tie inverters

Has anyone ever used a "plug and play" grid tie inverter? (An inverter that hooks up to a solar panel, and then plugs into an AC outlet) If you have, could you please post your experience with these? I am looking into purchasing one.

For those who don't know what I'm talking about, here is an example of one;http://www.gogreensolar.com/products/250-watt-grid-tied-inverter



Also, someone told me that not all electric meters can handle putting electricity back into my house. Is this true? And if it is, is there a way to tell if I have a meter that does allow me to?

Thanks a bunch!

Comments

  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: "Plug and play" grid tie inverters

    Please do a search on this site,,, there has been considerable considerable conversation on the subject so there is no reason to do it all over again.

    One note: The units are NOT UL listed and CANNOT be plugged in LEGALLY to the grid. You also run into insurance issues!

    Tony


    PS This is one of the discussion threads: http://forum.solar-electric.com/showthread.php?t=3051&highlight=simple+grid+tie+inverter&page=3 There are sure to be others!
  • BB.BB. Super Moderators Posts: 26,760 admin
    Re: "Plug and play" grid tie inverters

    GoGreenSolar appears to be a residence (at least where the RMA's are sent, with at least one other company registered there).

    What they are selling may work, but as Tony/Icarus said, it is difficult to believe that anyone will allow you to legally connect this inverter/system using the standard net metering agreements.

    For example, if you search for Delaware net metering agreement you will find:
    PV Installations Less Than 25 kW
    Most, if not all, residential installations and many non-residential installations fall into this size category of PV installations. For these installations, the interconnection requirements of Delmarva Power and the Delaware Electric Cooperative are fairly straightforward and standardized. Some basic requirements are:

    • PV systems must comply with the Institute of Electrical and Electronic Engineers standards for PV Systems.
    • PV modules need to be certified by a nationally recognized testing laboratory as meeting the requirements of a Underwriters Laboratory (UL) standard.
    Inverters must be certified by a nationally recognized testing laboratory for safe operation and certified as meeting a UL standard.

    For PV installations less than 25 kW, solar contractors usually fill out the appropriate interconnection agreement forms and make sure a PV system is properly connected, although the utility account holder’s signature on an interconnection agreement is required.
    • Will the vendor stand behind product. Don't know.
    • Will the inverter work? Don't know.
    • Will it be safe? Don't know.
    • Will it be legal? No.
    • Will your home be safe. If you have lightning in your area, probably not.
    • Will it meet building & NEC codes. No.
    • Should you do it. No.
    • Has it been done by others before and nothing happened. Probably.
    • Is it worth $0.10-$0.20 of power per day per inverter--not to me.
    $350 inverter and $1,250 for 250 watts of solar panels, assume 200 watts * 4 hours per day average per year, assume $0.15 power cost:

    ($350+$1,250)/(200w*4 hours*365d/y * $0.15pkWhr *1w/1,000kW)=36.5 years payback...

    And, presumably, this installation would not (legally) qualify for any State or Federal rebates/tax credits.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: "Plug and play" grid tie inverters

    My opinion of such hardware would be much more favorable if you could get UL or CSA listing, and it was acceptable to the utility. Since these products seem to have anti-islanding so that they can't back feed a dead grid it seems that they could be made safe. It these were listed and legal, it WOULD allow people to put in very small scale PV systems. The wouldn't really pay, but it would be a way for people to see how the whole thing works,,especially if they couldn't afford a large conventional grid tie system.

    Tony
  • BB.BB. Super Moderators Posts: 26,760 admin
    Re: "Plug and play" grid tie inverters

    Forgot to answer your other question...

    Older mechanical meters (over a decade or so) old, may turn both forwards and backwards.

    Newer mechanical and electronic kWhr meters may or may not turn backwards--it is up to your local utility and how they ordered their meters.

    Sometimes, you can search for your brand and model of meter and find the specifications (and options markings) online.

    Depending on the loads in your home, you may never generate enough energy to turn your meter backwards at that low of power levels (200 watts or so will power a fridge and standby loads for TV's, home entertainment systems, some cell phone chargers, door bell transformer, etc.). In those cases, your meter will just simply turn "forwards" at a slower rate.

    Lastly, if your utility suspects you have connected any GT Inverter without filling the proper paperwork (my meter has a notice to the meter reader that the meter does turn both directions--plus there are solar power warning stickers on the meter boxes and disconnects, and a note on my account of same)--The utility has the right to disconnect your electric service. And your local building department could tag your home not fit for habitation without electric power.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: "Plug and play" grid tie inverters

    Thanks a lot for all your help. After reading what you both have to say, I'm pretty sure I'm not going to buy a plug and play grid tie inverter ;)
  • eman21401eman21401 Registered Users Posts: 4
    edited April 1 #7
       Hello, I bought two plug and play GTI units on ebay recently. They work great and are perfectly safe on dedicated circuits... Yes, these units do have anti- Island protection as per NEC regulations. Which brings up the question, Why hasn't the NEC properly addressed these useful devices by now ? Yes, they are not UL approved or listed, but they should come up for review. They have been out for several years. They could make quite a difference. I started off with a battery based system.
  • eman21401eman21401 Registered Users Posts: 4
    looking forward to your comments...
  • mike95490mike95490 Solar Expert Posts: 7,249 ✭✭✭✭
    eman21401 said:
       Hello, I bought two plug and play GTI units on ebay recently. They work great and are perfectly safe on dedicated circuits... Yes, these units do have anti- Island protection as per NEC regulations. Which brings up the question, Why hasn't the NEC properly addressed these useful devices by now ? Yes, they are not UL approved or listed, but they should come up for review. They have been out for several years. They could make quite a difference. I started off with a battery based system.
    The device mfg has to submit a couple devices to UL and pay for the testing.  If that's too hard to do, skip the test and sell from ebay - more profit and they have "plausible deniability" when your house burns down.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • jonrjonr Solar Expert Posts: 845 ✭✭✭✭
    You say that they are "perfectly safe" and meet the regulations.  How can you be sure of this?
  • eman21401eman21401 Registered Users Posts: 4
    jonr said:
    You say that they are "perfectly safe" and meet the regulations.  How can you be sure of this?
    Thanks for your comment. I have installed 5 of these systems and have been using them everyday for the past 8 months. They work great ! As far as safety, plugging them into a dedicated circuit solves the stray current issue. Also, using only half of their rated wattage is a good idea to prevent possible overheating. As for regulations, they are not NEC approved or UL certified. That is a issue I hope they address when they re-convene to update the code book.  I suspect big business and politics plays a part in that decision. I am a Master Electrician in MD USA .
  • BB.BB. Super Moderators Posts: 26,760 admin
    NRTL verifications are more than first article inspection.

    There is material tracking (is the flame proof plastic traceable back through suppliers & raw materials), manufacturing processes and safety tests, equipment calibration, unannounced inspections once or twice a year, etc.).

    There used to be trade barriers (could not import into xyz country until you paid for local testing & certifications).

    For several decades now, the NRTL (Nationally recognized testing laboratories) system had pretty much eliminated those trade barriers.

    Plug and play gt inverters are not an issue when you have dedicated AC "solar" circuits.

    Any derating you may apply could help, but they do not make the units "safe".

    I can understand companies not wanting to pay $xx,000 to List a product, and for ongoing listing services -- But UL started as an independent insurance laboratory/agency to reduce loss of property and lives from fire (and reduce insurance company costs).

    If you are installing these systems as a contractor, you may be leaving yourself open to legal issues later.

    An example here:

    http://forum.solar-electric.com/discussion/3375/panel-fire-question/p1

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bill von novakbill von novak Solar Expert Posts: 694 ✭✭✭✭
    eman21401 said:
       Hello, I bought two plug and play GTI units on ebay recently. They work great and are perfectly safe on dedicated circuits... Yes, these units do have anti- Island protection as per NEC regulations. Which brings up the question, Why hasn't the NEC properly addressed these useful devices by now ? Yes, they are not UL approved or listed, but they should come up for review. They have been out for several years. They could make quite a difference. I started off with a battery based system.
    They have been out for much longer than that.  I ran some tests on a 120VAC pluggable inverter about 15 years ago.

    "They could make quite a difference" is a problem.  If they did "make quite a difference" - if people were installing 3KW+ systems with these units, similar to the sizes of existing systems - then you'd either run into serious safety problems running 3KW on 120VAC circuits, or you'd  be running several dedicated circuits for these.  And if you did that, you'd wonder why it's a problem to hardwire a single circuit for an inverter, but it's easy to run several more circuits just for this.

    (OK so solution here - use a 240V 30A plug, so that 1) you can't move it to an undedicated line and 2) you get much more power.  Great, that solves that safety issue.  Now you have to deal with grounding.)

    Also, people unplug stuff and then plug it back in, often in a more convenient location.  That will cause a problem with these, because consumers don't know what circuit goes where in their home.  And they will work just fine plugged into a non-dedicated line, at least until the fire starts.

    I have installed 5 of these systems and have been using them everyday for the past 8 months. They work great !

    Did you run a dedicated 120VAC line for every one?  If so, was that really cheaper than running a single 240VAC circuit?

     As far as safety, plugging them into a dedicated circuit solves the stray current issue. Also, using only half of their rated wattage is a good idea to prevent possible overheating. As for regulations, they are not NEC approved or UL certified. That is a issue I hope they address when they re-convene to update the code book.  I suspect big business and politics plays a part in that decision. I am a Master Electrician in MD USA .
    I suspect the biggest reason is that no one can figure out the problem with overloading a specific circuit.  (And no, you cannot get around that by just saying "use only dedicated lines" because people can and do ignore such warnings.)  And that means that UL does not want to certify devices that can cause fires, because that degrades their reputation, and they rely on their reputation.  Likewise, reputable manufacturers do not want to sell devices that pose such risks - although when you add the isolation of a different country's legal system, such devices are indeed available.

    For a case in point, look at the problems Orison is having getting their grid interactive batteries approved.  Similar problems.  And they have a much easier task - they don't have to deal with lightning protection.
  • EstragonEstragon Registered Users Posts: 1,418 ✭✭✭✭
    Two separate issues really IMHO.

    As Bill said, there's the device itself, which UL (underwriters - insurance interest - labs) test to ensure meets standards for consistent material and production quality. As a master electrican, you wouldn't want to install wire that could be copper, could be aluminum, could be whatever's cheapest to make at the time. You'd also like to know the insulation temperature rating is reliable. Insurance companies like to know the same thing for the same reasons. The material or device will have the properties described within a defined bound of certainty.

    The NEC is more about how things are used. As a master electrician, you'll know that a 15a breaker may be a fine, reliable device, but if you put it on a circuit with 18ga wire, not so much. I have issues with bits of the NEC, but for the most part it tries to make assembled systems safe, as they are commonly used, and resiliant with a single fault.

    A non-ERTL approved product used in a non-NEC application is not a failure of either ERTL labs, or the NEC. It's a failure of manufactures to test and make a case for safe use of their product.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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