How to add an external gfdi

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  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    I will probably go back to 10 when I am ready to use the other 2 panels. 10 will produce 1800 watts, and even 8 will probably produce 1800 watts when the sun it out. With 12 pannels I have been producing 1800 Watts since 10am, and it is cloudy. I used 10awg wire, then converted to 12 awg to go into the inverter (that is as large as it will use). They all go in a series, then go about 35 feet to the inverter. However I have been measuring my voltage at the inverter, and even 8 panels it never dropped to 200VDC, but it seems to like it better at 300VDC or higher. The thing that is kindof odd, is that watching the voltage, it will stay steady for a while, then it will jump around about a 30-40v range for about 30 second, then go steady again. Is that the inverters mppt searching? I am wondering if the voltage is close (within 100v) then it causes it to spike below 200v so fast that the voltmeter does not show, but it resets the inverter?

    I live in Weston ID, 42.0372° N, 111.9786° W

    solarvic wrote: »
    Why don,t you try 11 panels and see if you still get 1800 watt output? Another suggestion, Did you use heavy enough wire from panels to inverter and what is the length from panels to inverter? If you have too small of a wire you would lose some voltage. Maybe you needed all the 12 panels to overcome the voltage drop. I know some people are parinoid about putting thier location on thier particulars but it would make it easier about trying to give them advice. Temperatures and location give posters more info to help diagnose thier problems. What might be right for my location would be altogether than someone living in Florida, Per Say. If you livedSomewhere like in Canada where they might get -40F 12 panels mght be too much but if you lived in Florida you might need all 12 panels just to get your inverter to work. :Dsolarvic:D
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    By the way, here is a picture of the panels.

    Attachment not found.
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: How to add an external gfdi

    There are times when it may be an actual GT Inverter internals issue... Try giving the Mfg. customer support line a call and ask. On rare occasions, there can be a software upgrade involved.

    It sounds like you have gone above and beyond in your testing.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: How to add an external gfdi
    I hooked up all my solar panels (a total of 12). I was planning on using 4 of them for battery charging for another project. With 12 I have not seen it shut off at all, and the voltage is around 350 or so. It goes up to 15 amps output even when cloudy, but I feel like I am not utilizing my panels very well (almost 2700W of solar panels only putting out 1.8kw).

    So I guess this was the problem, but it doesn't make sense to me that the inverter won't just work at any voltage over 200. It should say you need 300-600VDC, not 200-600VDC.

    OK lets do some rough arithmetic:

    1800W / 15 A = 120V on the output, (good) so now 1800W / 350V = ~ 5.1A Very poor
    and 350V / 12 panels = 29V per panel ( good)
    corrected 5.1A from 12 panels ( Not great)

    from previous posts (SVic) the panels are ~220W rating / 29 V = ~7.6A per panel

    So you are losing ~ 2.5 amps (20%) per panel.... IMHO it is a wire size/distance issue or a bad wire connection somewhere ...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    The max output of the inverter is 1800 Watts. So I think it is just limiting it somehow when I reach 1800w.
    westbranch wrote: »
    OK lets do some rough arithmetic:

    1800W / 15 A = 120V on the output, (good) so now 1800W / 350V = ~ 5.1A Very poor
    and 350V / 12 panels = 29V per panel ( good)
    5.1A / 12 panels = 0.425 A per Panel ( NOT good)

    from previous posts (SVic) the panels are ~220W rating / 29 V = ~7.6A per panel

    So you are losing ~ 7 amps per panel.... IMHO it is a wire size/distance issue or a bad wire connection somewhere ...
  • solarvicsolarvic Solar Expert Posts: 1,060 ✭✭✭✭
    Re: How to add an external gfdi

    I agree with westbranch. But is seems you didn,t get the message I was trying to convey to you. The temperature and where you live has a lot to do with what kind of output you can expect. For me I only live south of Lake Erie about 50 miles and get a lot of cloudy days so need more panels than someone that lives where it is more sunny. Are these solar panels new or are they some of the ones that someone was sellling on EBAy that might be the ones someone got replaced because the outp[ut was too low. BP had some bad panels that were rep[laced. On of the monitors here had his replaced under warranty because of low output. Guessing someone got some of them and sold on Ebay. Still might work, Just need more of them. :Dsolarvic:D
  • solarvicsolarvic Solar Expert Posts: 1,060 ✭✭✭✭
    Re: How to add an external gfdi

    David. I missed the post where you said your location is. Your latituse is similar to mine and I planned my solar array for -22f and high temp of 98 f. So I don,t think you would have any problems with using 12 panels but for sure I would try just 11 panels and see where that puts you. If you can get the full 1800 watt output most of the time with 11 then maybe you could get some more for the other project. Remember you probably might need to try to get this all on the 2012 tax year for your 30% tax rebate. I would follow Bills advice ant talk to engineers at exeltech to see if they think there are any issues. :Dsolarvic:D
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: How to add an external gfdi

    I will bet Cdn dollars to donuts that the problem is probably 1 or 2 of the original array of , was it 8?, that is causing the problem. I am leaning towards a low A producer and it is pulling the array output down.
    I think that you have shown the additional ones are OK as output rose when they were added. Is it possible to disconnect some of the original ones, one at a time?

    hth
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    Thanks all for the input. I really don't think the problem is the panels because:

    1- the original panels put out 12-13A before the inverter would reset, which is not bad output.

    2- With more panels it increased until it hits the max output of the inverter (15A).

    So the problem is that the inverter needs 300vmp to keep it running, but I can't get that without 11-12 panels (10 was working well too).

    So I think I need to do what was mentioned, and call the company and see why it is resetting with 230-250v. If the inverter needs that high of voltage, I will just have to run the extra panels and loose the extra power produced , or get a different inverter (I should have got the 2500watt inverter I was thinking of getting).

    Thanks.

    p.s. I can disconnect each one individually.
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    Sorry, I have been reading over this a few times, and the last little bit is confusing to me. Since the panels are in series you can't divide by the number of panels, so each panel is really putting out an average of 5.1A, not 0.425 (unless I am missing something). Still not great, but not as bad as your post made it look.

    Also, before adding more panels, the 8 panels were putting out at least 12A*125v=1500W which is 83% of the panels rated output. It has gone up to 13A*125= 1625 which is 90%.
    westbranch wrote: »
    OK lets do some rough arithmetic:

    1800W / 15 A = 120V on the output, (good) so now 1800W / 350V = ~ 5.1A Very poor
    and 350V / 12 panels = 29V per panel ( good)
    5.1A / 12 panels = 0.425 A per Panel ( NOT good)

    from previous posts (SVic) the panels are ~220W rating / 29 V = ~7.6A per panel

    So you are losing ~ 7 amps per panel.... IMHO it is a wire size/distance issue or a bad wire connection somewhere ...
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: How to add an external gfdi

    Ooops, my bad, will correct original post, I should not have divided by 12.

    What is strange is that adding more panels stabilized things and gave some improvement in output, somethings just not right...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    Just to update, I just got of the phone with xltech, and they confirmed that it is a low voltage, and that it is caused when the mppt adjusts every few minutes to make sure it is correct. When it does it can spike the voltage down bellow 200v faster than my meter can read it. He suggested 9-10 panels, and said there was nothing that could be done with the inverter to change how it does that.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: How to add an external gfdi

    With that low an Amperage output, it begs the question : what is the benefit of the MPPT function in this case? To get it to work adn be stable, you have to over-panel, a lot IMO.

    Seems like PWM would give just as much and be more stable.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    Yes, I think it is a wast with my panels. If I were to do it again, I would get a higher watt inverter, or get higher voltage panels. If I had an array of 400-500VDC, and 1800 Watt, then I think it would work great. I think 10 180W 24v panels would work great.
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: How to add an external gfdi

    Probably depends on how long the MPPT "scan" lasts... If it is only a fraction of a second every hand full of minutes--then it is not killing the overall output by very much at all.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    Well it does if your panel voltage is near the range of the inverter, and causes it to restart at each scan.... With higher voltage, the scan is fine.
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: How to add an external gfdi

    I agree that it is not ideal--But how long does it fail to output AC power during a scan? Fraction of a second, seconds, minutes (there is a 5 minute timeout if the AC output voltage/frequency goes out of spec.).

    It would not be difficult for them to "hide" the scan issues if they wanted during the design process (for example, only show the red LED if input voltage falls for >1 second--for example).

    Others here have experience designing MPPT based systems--Perhaps they can offer some insights into the trade-offs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    When it resets, the amperage drops to zero for a second, then it slowly starts climbing. It takes about 1-2 minutes to hit full power, then it resets again (with 8 panels).
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: How to add an external gfdi

    Yea--That is not good. :cry:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    Is there anything like a voltage multiplier that would double my voltage output of the panels?
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: How to add an external gfdi

    I don't think there is anything that would be practical for your needs. There are some products that are intended to help with shading/weak panels/etc... (www.solaredge.com ? And I am not sure exactly what they do) But I would not spend extra money on new hardware to try and "fix" your inverter's operation.

    At this point, it sounds like you may need to think about returning the product as it is not working well for your application.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    well at least I have learned a lot from this little project.

    I think I will just run it with 10 panels, and see how it works (it didn't shut off as often as 8 did).
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    Just an update. I have been running 10 panels, and it seems to work great. The only time it kicks off is when a cloud goes by or something. In the last 4 days it has averaged 8kwh put back into the grid per day. I don't feel like that is too bad, since I am also running my house at the same time, so it is probably putting out 10 or more kwh/day. Also it has not been perfect weather, some clouds, and a little rain.
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    Another update:

    with hot days, I have been having more problems. I increased to 12 panels, but even with that I would come home to check on the inverter and it would be off, blinking the code for solar array voltage out of range. I don't know why it wouldn't start back up again, and when I checked the voltage was over 400vDC. So I contacted xlgt again, and they are sending me a new inverter. They say the did firmware updates that should fix my problems. I am impressed that they would send me a new unit, but I really hope it fixes this. I will update again when I get the new unit installed.
  • DustyDusty Solar Expert Posts: 271 ✭✭✭
    Re: How to add an external gfdi

    So, did the new inverter solve the problem??? Hope so!
    Another update:

    with hot days, I have been having more problems. I increased to 12 panels, but even with that I would come home to check on the inverter and it would be off, blinking the code for solar array voltage out of range. I don't know why it wouldn't start back up again, and when I checked the voltage was over 400vDC. So I contacted xlgt again, and they are sending me a new inverter. They say the did firmware updates that should fix my problems. I am impressed that they would send me a new unit, but I really hope it fixes this. I will update again when I get the new unit installed.
    XW6048, 3.4KW PV, Grid-Tied, always tweaking.
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi
    Dusty wrote: »
    So, did the new inverter solve the problem??? Hope so!

    I have not received it yet. As of Monday they hadn't shipped it yet. I will update when I get the new one.
  • davidwillisdavidwillis Solar Expert Posts: 104 ✭✭
    Re: How to add an external gfdi

    When I got the new one, I hooked it up to 10 panels, and it has been working without turning off (at least not that I have seen). I hooked it up on Thursday, so it has been going 4 days, and they were hot days in the 90s. So it looks like it has fixed it.
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