Grid Tie Inverters

Discussion in 'Connecting to the Grid' started by murray2paddles, Aug 1, 2009.

  1. jasincole

    jasincole WindyNation Engineer

    I watched the video on youtube where larry discusses his panel that he makes for around $550. Looks pretty damn nifty if I do say so myself. But, in that short ten minute video larry said something that I can not quite figure out. He stated that his setup is not selling back power to the electric company but instead is supplementing his power usage. Then in the next sentence he stated that sometimes he watches the meter going backwards. Now as far as I understand it, if the meter is going backwards then power is leaving your system and heading out to the grid. To me this is a clear statement that he is 'selling back power' as he will not be charged for that electricity since the usage you are charged for is directly related to the meter reading at the end of the month. Can anyone tell me exactly what he meant, if not larry himself, as I don't see the difference at all. Unless larry knows for a fact that he can not produce enough electricity to have a zero consumption at the end of the month and if he did the only way to get paid for that which he produces in excess is to use net-metering. I also live in PA about 2 1/2 hours north of larry and would very much like to know what he means. :)

    I plan on using a setup very closely to larry sometime in the future and if I can get away with non-ul listed grid-tie inverter then I see it as a cost benefit to me and am inclined to venture down this path myself.
  2. TomT

    TomT WindyNation Engineer

    Well I do not know how efficient my system is but I have an old electric meter and believe it or not it will go backwards.
    I am using a non UL with island protection. To sell back and or get energy credits for later in the year when usage goes up. Would be up to your energy provider. I am trying to just slow the meter so I will be close to 0 each month. So at this point I will monitor it myself and not go with NET Metering. But will check into it if they start complaining about low usage.
    They have once when I started using compact fluorescents and then again after I started using unvented heaters , put everything on power strips and turn them off when not using them. And only dry whites in the dryer. With all that I have cut usage down almost 70 percent from what I was using.

    Attached Files:

  3. murray2paddles

    murray2paddles WindyNation Engineer

    I do know what Larry means, Some states accept credits for sun only and not wind. I suggest you contact him on a private message so he can explain his situation to you.
  4. murray2paddles

    murray2paddles WindyNation Engineer

    It can happen another way also. My meter is the same as the photo of Tom's.
    We both have the older dial and clock style, these ones can turn backwards. I am not in a contact with my provider but am able to run my meter backwards on good wind days.

    I was told the newer style meters will not turn backwards, maybe some of you can share with us if that is correct .
  5. leamywind1

    leamywind1 WindyNation Engineer

    If you are supplementing your electric bill and you get to run your meter backwards now and then you are reducing your electric bill and power consumpion by wind or solar. If you are making enough power to cover your electric bill by more then 50% then you should go UL as the price tag to buy that much solar or wind is a lot. You would want to go UL to get your rebates and cover your cost.
    You are not getting paid for putting it back into the grid with a non UL inverter, only slowing your meter down or running it backwards to spin the numbers on the meter backwards that the meter reader is reading each month. Anyone using the non UL grid tie inverter would not be contacting the utility because most do not want to buy a UL inverter reagrding cost, or it will not work for a low voltage wind turbine, or go through all of the red tape to do it. From my experience the anolog type electric utility meters spin backwards and they are illustrated in this forum topic. I do not think the digital one's do although I have not had experience in seeing that. When I do a net meter system for a customer the utility comes and changes out the meter with a new one since all of my customer's get UL inverters, permits, inspections and so forth. As a business I can not install a non UL inverter for a customer due to liability issues for my business.
    Each utility is different. If you go back and go thruough all of my video's I explain this for a utlity company called PECO. I show and tell about the solar system and the net meter system required by that utility company.
    I deal with 3 in my state PECO, MET ED, and PPL.

    Most micro wind turbines will not work with a UL inverter due to the UL inverter needs to high of a voltage to operate. Sure I can wire them in series but why do that ? I am looking for the most power out of them starting at the lowest wind speeds. High winds is just not realistic to me. 30MPH maybe 10 times a year at my site. That is why I run 4 turbines inn paraelle. Jacking the amps and keepinfg low volatges. I produce more watts in lower realistic wind speeds of 6-15MPH winds. Solar panels are wired in strings. Very easy for 10 solar panels to hit 300v. Not so easy with a micro wind turbine, espicially just one. Sure you can install all kinds of gizomos-devices-transfomers to up your turbine voltage but, that will not pass inspection. Reconfiguring a UL inverter is out of the question.

    This is why we all are trying to use the China ones. Working at 10.8v is way easier volatge mark to hit, to make power from low wind to high. Trying to hit a voltage window of 100v + (even with MPPT) for a UL inverter would only come 3 times a year for most us out of hurricane force winds and we all know that is just no realistic.

    I can not speak for any utility company regarding using the non UL inverters but I have been using them for a while with my wind and I have not had one problem. I also live right down the street from my township building, you can see all of my turbines from miles away as I live on a hill. No questions asked from them either. You need to have several wind turbines or solar to start making any difference in green energy production. 300watts of anything in my opinion will not raise any red flags regarding grid tie. So I guess you have to have an answer for two things when using a non UL grid tie inverter. If I burn down my house with them will my insurance cover it? If my utility finds out what do I say?
    These are the two question you would need to figure out own your own.
    Any other questions I will be happy to try and answer.
    I hoep this helps

  6. Minnesota

    Minnesota WindyNation Engineer

    Speaking of these Chinese GTIs, here is a video on the INSIDES of the Sun 250 and the Power Jack 300:

    I have also done a series of performance vids on these units working separately as well as in parallel. I have more videos planned. They DO NOT work in parallel very well. One will heavily dominate.

    Here also is my database of realistic sustained power people have been seeing. By sustained I mean for hours on end without overheating, and in shaded 75F ambient air:

    SSI-200 (14V) 200w
    Power Jack 300 (14V) 143w
    Power Jack 600 (24V) 324w
    Power Jack 1200 (24V) 500w
    Sun 250 (10.8V) 150w
    Sun 500 (24V) 320w
    SFGTI 500 (12V) 360w
    GP2-400 (10.8V) 150w (only one data point so this likely is incorrect)

    The genearl rule of thumb is to stay under 50% of the sticker rating for all units other than the SSI-200.

    The biggest risk with these is overheating and having an input voltage that exceeds the upper end, limiting their use with wind turbines unless other steps are taken.
  7. TomT

    TomT WindyNation Engineer

    That one that I have is a direct connect. I just got an email back from the manufacturer.
    It drops out in high wind gusts when the voltage jumps over 28v. It does a good job keeping it below 28v but it high quick gusts it shuts down output and brakes the turbine to slow it down for approximately 5 secs and tries again. So I am going to keep it with the diode setup for now.

Share This Page