OK4U-100 GridTie Inverter Wiring Hookup

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System
System Posts: 2,511 admin
in Grid Tie and Grid Interactive Systems #1
Could someone please tell me the wiring hookup for a OK4U-100 GridTie Inverter. There are 4 wires on the output side, white, black, blue and red or orange. Which wire does what?

This is only my second week into the solar electric hobby. I was given 4 Bp 75 watt solar panels and 2 OK4U-100 GridTie Inverters. After some reading here I thought I might as well put them to good use and learn at the same time.

Thanks for the help.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #2
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    From here, it appears that the OK4U is out of production, unreliable, is not UL/NRTL safety rated (therefore illegal in the US), and does not include the-anti-islanding safety feature...

    So, from all of the above--it would be better if you did not install it--especially on utility feed power lines... The chances are small that anyone would be hurt/killed--but it is still there.

    Most information I could find with a quick look around the web was this website out of the Netherlands--You can try throwing it through Google Translate and see what you can glean from it (Tried Dutch>English and it sort of worked--maybe more German?).

    You can also try variations of Trice Microsine 100 and see if you find anything helpful there.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #3
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Thanks Bill for the post, not as encouraging as I had hoped but you are correct, the lack of anti-islanding is not desirable.

    I'll check out the site to see what information I can translate from it. Sounds like it might be more productive to parallel the 4 panels into an inverter.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #4
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    You will not be able to connect the four panels directly to a 12 vdc to 120 vac inverter successfully...

    A off-grid type inverter (standalone inverter) pretty much is designed for use with a DC battery type source. Solar panels just are not a stable enough voltage source--plus the inverter will shut down anytime you tried to draw any larger loads or the sun goes behind a cloud.

    You will either need to use a true off-grid system (panels, charge controller, inverter) or a larger grid tied system (usually 1,000 watts of panels would be the minimum practical with equipment available in the US today) and follow the regulations (building codes, NEC, utility requirements) for connecting utility interactive solar inverter (grid tied).

    There are other options/configurations possible out there--but not for smaller systems like this. Also, these other methods require a bit of engineering and solar/electronic experience to pull off safely (plus more $$$).

    If you want to build a very nice little off-grid emergency system (battery backup), look at these components:

    MorningStar MPPT solar charge controller (get the battery temp sensor option)
    MorningStar 300 watt inverter

    And while it is not cost effective for this small of system--I would still highly recommend a battery monitor too... It is the best way to understand how your battery is performing with the solar charger and inverter (if you over or under charge your battery--you will quickly kill them).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    interesting that you were given those items. your friend got any he could give to me?:D the used market is tough enough to find some items and it never stops to amaze me that so many have been given stuff like this. you can't blame me for asking if i can have some.;):D
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  • System2
    System2 Posts: 6,290 admin
    #6
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    LOL Niel sorry. It's my understanding that panels were acquired at a garage sale. Now that I am starting to understand the concept I am wishing for more or them.

    Following along with an earlier post in this thread I am leaning towards a setup using the MorningStar MPPT solar charge controller. My next quest is for a couple of reasonably priced deep cycle batteries. I have 2 high-pressure sodium yard lights and if I could run them off an inverter for free at night I would be satisfied. Here in Florida we have no shortage of sun so maybe the batteries would charge all day ready for the next night. I'll have to re-read some of the threads here, I think I saw something about calculating the amp hours for the demand.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #7
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Just to be clear--Solar electricity is a long way from free...

    Usually, utility power is around $0.10-$0.30 per kWhr...

    Solar PV Grid tied power is around $0.20-$0.50 per kWhr

    And off-grid solar PV power is probably $1.00 per kWhr or more (can be less, but usually more)...

    What adds a lot to the costs are the extra equipment (charge controller, inverter, batteries, battery monitor, and such), plus the fact that the batteries need to be replaced every 5-15 years...

    So--to keep your off grid costs low, conservation is the key word. For example, you don't want to keep security lights on 12 hours per night--but, perhaps, install motion sensors to turn on efficient flood/spot lights, etc...

    And, you can very quickly calculate the cost solar lighting vs utility power and string a few hundred feet of cable from your power source to the lights (or whatever).

    For example, assume a pair of 100 watt HP Sodium lights running 12 hours per night...

    100 watts * 2 * 12 hours * 1/(0.8 batt eff * 0.85 inverter eff) = 3.53 kWhrs per night

    That is 30days*3.53kWhr/day=106kWhrs per month

    Using this website and assuming you are near Daytona Beach FL, using 0.52 derating factor for off-grid solar, all else set to defaults, you would need about 1,656 Watts of solar panels to power these lights 12 hours per night through the three months of winter (summer, you would need less lights at night and collect more power because of the longer days).

    1,656 Watts of solar panels would cost around $8,000 (excluding batteries, charge controller, inverters, mounting etc.)...

    Battery wise, assuming 3 days of no sun, and 50% maximum discharge, you would need:

    3,530 Watt*Hours * 3 days * 1/50% discharge = 21,180 Watt*hours of batteries...

    Or, in Amp*Hours at the 20 hour rate (usually a standard rating) you would need:

    21,180 Watt*hours / 12 volt battery bank = 1,765 Amp*Hours of battery bank.

    Or, if you used a "golf cart" sized battery:

    Crown 395 Amp-Hour Deep Cycle Battery, 6 Volt

    2x (6volt battery) 1,765 Amp*Hours / 395 = 9 batteries (round up to ten, each battery weighs ~121 lbs)...

    Or around $2,500+ worth of batteries (which will usually last you around 4-8 years)...

    Of course, it could be done or you can change how much light, how long at night, etc...

    But your best bet would be to figure out how to do the night lighting using as little power as possible (and no matter the source of your power, you will require less of it).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #8
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Thanks Bill for taking the time for such a detailed post, I can see that I do have a lot to learn about this solar stuff.
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  • System2
    System2 Posts: 6,290 admin
    #9
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    Re: OK4U-100 GridTie Inverter Wiring Hookup
    Digi_Com wrote: »
    Could someone please tell me the wiring hookup for a OK4U-100 GridTie Inverter. There are 4 wires on the output side, white, black, blue and red or orange. Which wire does what?

    This is only my second week into the solar electric hobby. I was given 4 Bp 75 watt solar panels and 2 OK4U-100 GridTie Inverters. After some reading here I thought I might as well put them to good use and learn at the same time.

    Thanks for the help.

    Digi,

    If you're still interested, I have my OK4-U installation manual in .pdf format. Happy to send it to you if you want.

    Chris
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  • System2
    System2 Posts: 6,290 admin
    #10
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Please be very careful about connecting these to the grid.

    I strongly advise you to search for OK485 data interface and use the software to make sure they are operating correctly. I currently have two operating for 4 years and have managed to find a new one as a spare, but I have found out that even though the spare is labeled as 120 volt 60 hz, it is operating at 50 hertz when I tested it - so much for my spare inverter.

    I have the connection diagram available as PDF if you want a copy. Black/white go to 120 volt AC power, orange/purple are for data.
    Does anyone have the password to enable me to correct the frequency on my spare OK4U/MicroSine using the NKF software?

    I would be willing to buy those two inverters from you if you are interested.
    Sincerely, GoGoSolar.

    I too was trying to remove a sodium light from the grid and ended up making LED lighting as the sodium light was too power hungry for off-grid solar/battery operation.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #11
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Free solar power to light sodium lights=not free!

    Consider using changing you sodium lights for something more efficient, and then use your PV for something that might be a bit more useful.

    Tony

    PS Any time any one wishes to give away panels, particularly BP or Siemens I would be more than willing to take them...
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  • System2
    System2 Posts: 6,290 admin
    #12
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    During my system development, I did change out my 250 watt sodium to a so-called 70 watt sodium, thinking it would be better, but it burned out the first inverter (150 watt). I tested the actual consumption and it was actually 240 VA (volts times amps, 2 amp at 120 volt) but the 70 watt rating was Power factor adjusted, thus the inverter burn-out - the inverter didn't care about power factor. I designed and installed LED strip lighting under the eve of my garage, all the way around, and it consumes under 1 amp @ 12 volt DC. I have had this running over 5 years now. I have learned a few things from this project, including that all LEDs are not created equal, despite their ratings or batches.

    I was thinking fluorescent lighting, but here in northern Canada, the temperature gets too low for reliable operation.:D
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  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    #13
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    Re: OK4U-100 GridTie Inverter Wiring Hookup
    niel wrote: »
    interesting that you were given those items. your friend got any he could give to me?:D the used market is tough enough to find some items and it never stops to amaze me that so many have been given stuff like this. you can't blame me for asking if i can have some.;):D

    It is still surprising to us how often we hear stories of people giving away (or nearly so) panels - in one recent case a dozen 10-year old but never used 100 watt Siemens panels that someone had stocked up on for the Y2K panic at a yard sale for $20 each.

    What is more disconcerting though is that from time to time we hear stories about larger systems being just trashed. A few weeks ago some home foreclosures near Phoenix resulted in some 200 180 watt panels being ripped off the roofs with no regard to saving them. All were damaged far beyond repair.

    Even with all the solar hype in the past couple of years, there are still a lot of totally clueless folks out there.
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  • PowerGuy
    PowerGuy Registered Users Posts: 6 ✭
    #14
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    OK4U-100 GridTie Inverter Wiring Hookup

    We have two OK4U-100 (Microsine MS100) units on our tracking arrays to deal with a couple of panels that are not compatible with our series & parallel strings that are connected to an MX-60 charge controller, battery bank, and inverter. Initially, the the two MX100's generated a near maximum on the specifiocations, about 90 watts each, or about 1.5 amps at 124 vac combined. Lately, however, the production has dropped off substantially, to about 60 watts each. The panels are clean, and both MS100's seem to be doing the same thing. We do not have the data links connected, so do not know what is happening inside the MS100's.

    We found on the data interface sofeware on the internet and downloaded it. We also researched the RS485 to RS232 interface issue, and ordered a di-directional converter. We are not sure, but hope that this converter and SW will allow us to figure out what went wrong in the MS100's (if anything).

    For now, we would like to know if anyone has experienced anything like our drop off in energy production on the MS100's.

    Also, if anyone has any information on how to connect up the converter, the data leads and a computer serial port, we would appreciate any hints. We have an old XP laptop with a serial port set aside for this service.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #15
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    What brand/model/age of solar panels are you using? I would tend to think that the micro inverters will either work or die--and it would seem unlikely that they decline in output together... Also check wiring/junction boxes for corrosion. If you can measure panel voltage/current would be helpful too.

    Any brown/burned spots under the glass (make sure the glass is clean, my panels make a eucalyptus/oak leaf tea/stain where water/rain dries out and look all the world like burned panels at the lower edges).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • PowerGuy
    PowerGuy Registered Users Posts: 6 ✭
    #16
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Thanks for response. We measured the panel stats yesterday in strong sunlight at noon, and got OC voltage and current very near spec, also, when connected to the MS100's, the voltage dropped off to within 2 v of maximum power point, so appears to be operating OK. We agree that the modules should work at near 100% or not at all! We plan to check the amperage output directly this afternoon.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #17
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Also check the short circuit current (DVM set to 10 amp across panel leads/connection--OK to short a single panel).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • PowerGuy
    PowerGuy Registered Users Posts: 6 ✭
    #18
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Thanks BB. I misspoke in previous post. I measured both OCV at near spec and Short Circuit current, with a good Multi-meter (set on 10 amps as you suggest), and then voltage under load. Panel OCV was within a couple volts of expected, same with SS current. And, the voltage under load, i.e., connected to the MS100, was near maximum power point. I did not measure DC current under load but can still do that. I measured AC current out in strong sunlight and got only 0.21 amps, or about 1/4 of spec and 1/4 of what originally was measured when installed 6 months ago. Today, I checked all the connections and found them to be sound. I noticed that the voltage at the array with the MS100 offline was 123.6 vac and with the unit on line, but producing only 0.21 amps (26 watts where previously it was 90 watts), the voltage rises to 124.5 vac. This seems to be normal as the MS100 needs to have a slight increase in output voltage over line votage in order to create the power flow in the right direction. The MS100 seems to be rated up to 127 vac, so a higher line voltage than nomimal 120 vac should not be the problem. As I have two MS100's and both are doing the same thing, and started doing it at the same time, the cause would not appeare to be inside the MS100's. I have ordered the RS485/RS232 converter and downloaded the MS100 sofeware, so may, if I am very lucky, be able to interogate the units to see if that helps to narrow down this problem.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #19
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Sounds like you have narrowed the problem down... Enphase would probably be the nearest replacement units at this time.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • PowerGuy
    PowerGuy Registered Users Posts: 6 ✭
    #20
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Yeah, assuming I wanted to rewire the entire installation for 220 vac! No 120 vac units currently available, apparently.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #21
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    There is a company that makes 120 VAC GT inverters (need to be mounted inside structure) called SWEA... But I would not recommend them myself.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • PowerGuy
    PowerGuy Registered Users Posts: 6 ✭
    #22
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    I will check it out, was not aware there was another 120 v system out there other than the discontinued MS series.

    The mystery deepens. I just checked the 100 watt panel I have connected to the MS100. It is running at 35 vdc and 2.6 amps while connected to the MS100, very near the MPP voltage and only 0.5 amp short of MPP amperage (3.05 amps), but it was only 8 am local time (not DST) on our tracking array, so this was normal. Thus, the panel is operating properly and is putting out 2.6 x 35 = 91 watts (91% of spec) and the MS 100 was producing 0.21 amps at 125.6 vac or 26.4 watts. Based on simple physics, the missing 65 watts must be showing up as losses and thus extra heat in the MS100, but it seems to be operating normally.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #23
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    There is always the possibility of a meter/measurement error too (rare but DVM/etc. have failed in many weird and wonderful ways--and check the meter batteries too)... The "lost energy" does not sound "right" (of course, it is possible that the inverter is failing "this way").

    I am not recommending the SWEA--If it is possible to rewire for 240 VAC--then I would go with the Enphase (or other new brands coming out now) than the SWEA.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • PowerGuy
    PowerGuy Registered Users Posts: 6 ✭
    #24
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    Re: OK4U-100 GridTie Inverter Wiring Hookup

    Meter error was considered a possibility, so we measurred it directly with a Digital multimeter, a clamp on inductive amp meter, and also measurred the output contribution at the watt meter that totals all energy production from the arrays, both MX60 and MS100's controbution. All agreed that the output from the MS100 was only about 20 to 26 watts rather than 85 to 90 watts. It would appear that the output has dropped off dramatically but we are concerned that both of our MS100's did the same thing simultaneously. We are waiting for delivery of the RS485/RS232 converter and hope that we can establish contact with the MS100's and ask them what the heck is going on! Thanks for your input.
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