Grid Tied Grief!

[gtuplin]

[QUOTE=sensij;n324966]Please take a picture of how the final wiring is connected at the inverter. If the inverter has several mppt's, but you have just one combined home run, you need to make sure only one mppt is active.


Good idea, I will take a picture and post. I am not sure but if the dc control board combines at the inverter would it be default one MPPT? When only one terminal (dc) is connected the 4 terminal
are live so I thought this to be a load or input sharing strategy but just assumption on my part.

[SunEagle]

I still think there is a wiring issue. Unless I am reading the data sheet wrong the Growatt 10000 only has 2 MPP strings each rated 36A. Yet you mentioned 4 strings of 12 x 250 watt panels each. That would require wiring 2 sets of 12 in parallel and then wire each of those pairs to one of the input strings on the inverter.

Is it possible that the electrician got the + and - wrong on a some of those parallel wired sets which could have canceled the production output?

[gtuplin]

I still think there is a wiring issue. Unless I am reading the data sheet wrong the Growatt 10000 only has 2 MPP strings each rated 36A. Yet you mentioned 4 strings of 12 x 250 watt panels each. That would require wiring 2 sets of 12 in parallel and then wire each of those pairs to one of the input strings on the inverter.

Is it possible that the electrician got the + and - wrong on a some of those parallel wired sets which could have canceled the production output?

Well guessing that anything is possible at this point, does the data below make sense? I am sure he assumed that the 1-4 string would mean dividing into 4 strings was the best choice. again what you are saying makes sense to me.

I am just looking in the manual and here is what it says:
Input data:
max dc power 10350W
max dc voltage 600v
start voltage 360v
dc rated voltage 379v@240v
pv voltage range 345-600v@240v
mpp voltage range 345-480v@240v
max input current 36amp
max input current per string 16amp
number of mpp trackers/strings per mpp tracker 1/4

[SunEagle]

Well guessing that anything is possible at this point, does the data below make sense? I am sure he assumed that the 1-4 string would mean dividing into 4 strings was the best choice. again what you are saying makes sense to me.

I am just looking in the manual and here is what it says:
Input data:
max dc power 10350W
max dc voltage 600v
start voltage 360v
dc rated voltage 379v@240v
pv voltage range 345-600v@240v
mpp voltage range 345-480v@240v
max input current 36amp
max input current per string 16amp
number of mpp trackers/strings per mpp tracker 1/4

That is a little different from what I read. The data sheet was the same except it had the max input current per string at 36amp and the number of mpp trackers/strings per mpp tracker 1/2. Maybe it is a different model.
This was for a Growatt 10000TL-US

[gtuplin]

That is a little different from what I read. The data sheet was the same except it had the max input current per string at 36amp and the number of mpp trackers/strings per mpp tracker 1/2. Maybe it is a different model.
This was for a Growatt 10000TL-US

No same model, but I did check on line and found that as well but when I clicked on data sheet it was the same as my manual. I expect data sheet to be correct but then again?

[gtuplin]

Sorry if you get multiple replies I seem to having some posting issues.
So yes its the same model, I also checked on line and found the tech on it but once I looked at data sheet on same page it appears the same as my manual.

[bcroe]

My feeling is that it isn't a wrong wiring issue, because I didn't see that causing the power to drop as
the peak time approaches. That doesn't rule out DEFECTIVE wiring, but that would likely show up as
a lot of heat and maybe smoke. Therefore the component tests I listed could be done in a day or so. Bruce Roe

[gtuplin]

[QUOTE=gtuplin;n324971]

Please take a picture of how the final wiring is connected at the inverter. If the inverter has several mppt's, but you have just one combined home run, you need to make sure only one mppt is active.


Good idea, I will take a picture and post. I am not sure but if the dc control board combines at the inverter would it be default one MPPT? When only one terminal (dc) is connected the 4 terminal
are live so I thought this to be a load or input sharing strategy but just assumption on my part.

Several pictures of bare board as well as final configuration of running inverter. The rear view of the bare board appears to combine all connections.

[Mike90250]

First, with a system of this size, you should be running DC circuit breakers in the combiners, not fuses. Fuses are generally not safe to remove when there is power present, and you will draw a huge arc, destroying the fuse clips. Same with the MC4 connectors, never mate/disconnect with power in the system, they are not designed to break a circuit and will destroy the gold plating.

> mpp voltage range 345-480v@240v So, this is the target voltage range for your PV strings, so in cold winter morning conditions, they are bumping that upper limit of 480 - 500VDC, and in summer, heat fade keeps them above 345VDC.

[gtuplin]

First, with a system of this size, you should be running DC circuit breakers in the combiners, not fuses. Fuses are generally not safe to remove when there is power present, and you will draw a huge arc, destroying the fuse clips. Same with the MC4 connectors, never mate/disconnect with power in the system, they are not designed to break a circuit and will destroy the gold plating.

> mpp voltage range 345-480v@240v So, this is the target voltage range for your PV strings, so in cold winter morning conditions, they are bumping that upper limit of 480 - 500VDC, and in summer, heat fade keeps them above 345VDC.

Ok so maybe my terms are incorrect ( I did apologize in advance) I believe they are a combiner/ DC disconnect? This is one of the only approved products available here and seriously expensive!! Nothing would ever be removed until load was off, cant remove fuses until locked out it appears. I have added a few pics.

[DanS26]

I know this sounds too basic or too obvious...but have you checked all the fuses in the combiner boxes for continuity?

You need a DC clamp on ammeter to compare output of each string. That is how you are going to diagnose this problem. If all strings have the same low current, then disconnect two of the strings, then measure current again. If current goes up for the remaining strings then your problem lies with the inverters.

Make sure you power down the inverters and open DC disconnects before disconnecting strings......you can do damage by disconnecting strings under power.

[gtuplin]

Nothing is to basic when your trouble shooting but yes all fuses are good and have spent the day tracking data so come sundown I will have a complete log.
One of my tests today was basically that but because I don't have the clamp on and the electrician is off for the weekend I did it this way. I started inverter and took reading of watts producing then turned off inverter went to DC combiner /disconect turned it off then de fused one string at a time and the result was about 25% decrease in production each fuse/ string. That would indicate to me that each string works in a correct proprtion to out put but still provides no reason for the overall lack of production.

[sensij]

It looks like black and red wires are being combined in the combiner. Am I seeing the picture correctly?

[gtuplin]

[QUOTE=sensij;n325019]It looks like black and red wires are being combined in the combiner. Am I seeing the picture correctly?[/QUOTE

Yes but it appears all 4 lines at the fuse breakers are live positive I can double check tomorrow to eliminate, I will follow lines back to junction boxes.

[gtuplin]

So after collecting data all day and a few tests I really don't have anything concreate but do have a lot of strange things going on!
I conducted a test that was designed to test the line full theory or grid not accepting output, not sure if its a perfect test but best I could think of. I first took readings from each of four invertors then went up to the 10kw house system and shut it down then added a large load to the grid then back to the 4 inverters to check if it ramped up but no notable change was found. Next I took readings from invert 1 and turned off 2, 3, 4 in hopes that the single inverter would ramp up but no notable difference found. Next I shut down one system removed 3 fuse/ breakers in combiners then engaged system again but found that the readings were about 25% of the full recorded value and increased by the same as the other strings were added.
The output today seemed better than yesterday but still about 1/3 of expected output and each inverter showed a steady increase in wattage as the sun came around up to about 3200 by 11:40 but then it starts to fall off. By next reading it was down to 2110 at 12:45 then 1606 at 4:00 so for what ever reason I decided to shut all the systems down ( I was checking something just didn't make a note of it) but when systems were put back on line the numbers jumped considerably and about the same value to each system but this one I was tracking went from 1606 at 4:00 pm to 2490 at 4:20 PM and continued to climb to about 2700 by 4:40 and then slowly downward to 330 at 6:55 pm. It was still sunny but the systems shut down very early due to lack of amperage, voltage is still up and the inverters continue to try to restart .
The total out put today from 48,000w system was 108KW, the house system 10,000w was 62kw. Not a shining review!
So back to my original question, does anyone think that the high power overhead transmission lines could be causing some interference in some way or how about my new 50kv transformer could it be malfunctioning? can that even happen? Can the grid refuse power? Should I continue a search for a duplicated wiring error?
The only thing I really know are that my panels test fine singly, all strings are consistent, all inverters react identical and that when up and running I am at 20-25% of expected out put
Kinda running out of things to test!
Anyways I appreciate the feed back, Thanks