Author Topic: No brand/5500W inverter disaster porn  (Read 1045 times)

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Offline lighthunter

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Re: No brand/5500W inverter disaster porn
« Reply #60 on: June 13, 2021, 08:29:48 pm »
Hey guys!  I have some new? 245w panels i want to put on a tracker i havent built yet and watts are wasting so since my main 2 channel grid tie is no longer maxed out at 3600 because of the heat its running at 2560w in the hottest parts of the day, i thought i'd add a few (5) of the panels to one of the arrays.

I started by measuring the mppt voltage at 255v and current at 6A. Then i added 5 245w 60 cell panels which shouldve bumped voltage up to 380v (30-5v each for heat=25) and current relatively unchanged. That isnt what happend. The grid tie mppt somehow choose to run it at 428v and 3.5A to 4A.  The gti output went from 2560w to 3200W so output improved but not like it should have.  I saw it at 3600 even a couple weeks ago when it was cool. The other string was running between 6 and 7 amps at 210v today and the currents are usually similar.

So im guessing its because i have a mixed group of panels in a string but its wierd ive never had that issue before. I was gonna throw on a different grid tie inverter to see it missed the correct mppt voltage like this one but it wouldnt turn on... frequency fault. Now after all the rambling... the relevance to this thread. So the 8010 48v inverter in the original post is making sine wave at 60.2hz. Kinda odd, i knew it was slightly off because my phase align detector relay switches on and off like every 3-5 seconds and the pj i used to use took over a minute sometimes 5 minutes for the phases to align meaning the frequency was matched to grid very close.

I dont need to change this immediately but i will at some point, guessing the 0-100hz adj mode would be easiest, i also thought about adding a cap to the crystal to slow it down a bit but might make it less stable.

So has anyone else had an mppt lock in at the wrong voltage? I tried dropping panels out one by one, nothing resolved it. I even checked max current of the entire array which was over 7 amps proving all connections were good and every panel was carrying current.  *edit* i realize somethin about the numbers dont add up. The current shouldnt have dropped so low though which i think indicates a problem.

Hope everyone is having fun and enjoying the sun :)
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Offline Pete

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Re: No brand/5500W inverter disaster porn
« Reply #61 on: June 14, 2021, 03:39:55 am »
Hi LH , my take is that it will depend on the current that the new panels are able to produce. Their maximum current will be the maximum current in the string,
I don't have a grid tie so don't know how that stuff works, I tend to mix panels by wiring them to separate regulators in parallel.
That way I can mix different string voltages and currents.
Then my regulators only handle 100 volts max and 50 amps out. So that is my limit on each string.
There is a possibility that you have a high resistance joint on one of your connectors, if you are using those plugs and sockets that the panels come with they can sometimes not be seated properly and not make good contact.
Hope you find the problem
Pete

Offline dochubert

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Re: No brand/5500W inverter disaster porn
« Reply #62 on: June 14, 2021, 12:18:38 pm »
Hi guys,
I think Pete may be right about the new panels limiting your max string current, making the mppt voltage go up instead.  What's the current rating on the added panels versus the current rating on the original panels?  Just guessing here but sounds similsr to what happened to me adding panels to my grid tie string back in San Diego.  In my case the panels I added were higher wattage but output didn't increase as much as I figured.  Don't remember what the actual numbers were, but the results of adding dissimilar panels was disappointing.
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Offline lighthunter

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Re: No brand/5500W inverter disaster porn
« Reply #63 on: June 14, 2021, 06:48:52 pm »
Yeah, i agree, I need to split the new ones into their own group. Since they are 60 cell i can move them to another spot that already has 2 strands awg6 or 13.3mmsq wire and direct connect to 48v battery, others have mentioned this works well. Im wondering aboutthe heat compensation. 2 x 30v panel -5 each for heat = 50v mid day max pwr volts. Battery volts is usually 54-56v mid day, wont that hurt output? Lets see, 50 vs 55 is 2.5v above max power per panel. String configuration error is 428v - 380v = 48v รท 16 = 3v mpv error per panel. Both errors are same direction. Maybe i better get busy like Pete an build the array rack n pivot an put all 12 together an see if the inverter can find the 340-360v sweet spot. All the fancy mppt stuff i wish they were just designed to adjust array volts manually with a temp compensation. Thanks guys!!
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Offline Pete

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Re: No brand/5500W inverter disaster porn
« Reply #64 on: June 14, 2021, 10:29:14 pm »
Hello again LH. Remember that the voltages on the panel label that relate to maximum voltage at full power will change. As the load decreases the panel voltage will rise towards the open circuit voltage.
I have never seen my panels at full output. The sun sneaks up and the panels start to charge the batteries long before the full sun gets on them. So the regulators are throttling back well before the panels are putting out their maximum power.
I think you are on the right track with splitting up the odd panels. From the labels they seem to have very different specs.
Pete

Offline Pete

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Re: No brand/5500W inverter disaster porn
« Reply #65 on: June 14, 2021, 11:08:59 pm »
Here are a couple of pictures of my new panel rack. We get very strong winds on the mountain so it is (hopefully) solid enough.
Pete

Offline lighthunter

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Re: No brand/5500W inverter disaster porn
« Reply #66 on: June 16, 2021, 06:19:01 pm »
 Beautiful work Pete! It would take a lot of wind to bother that mount! Looks strong, you got some good materials and fair bit of work into that project. Guessin you have a reason they are off the ground a bit. My solution to wind is to be back against a grove of trees and the front down low so wind cant get much lift. We have deer but so far they havent run into my panels. Seems like someone here mentioned Emu can be troublesome.

Keep up the good work! It pays off, i know i sure enjoy a good hot shower from solar heated water each morning!
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Offline dochubert

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Re: No brand/5500W inverter disaster porn
« Reply #67 on: June 16, 2021, 07:45:23 pm »

Pete!
That's an awesome panel mount!  Stronger looking than a lot of buildings.  In fact you could probably close in the front and back, put a door on the end and use it for storage! :)
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Offline Pete

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Re: No brand/5500W inverter disaster porn
« Reply #68 on: June 16, 2021, 07:55:00 pm »
LH ,No Emu here but we do have Wombats ( think miniature bulldozers). Wallabies and Possums abound here too, but the Wallabies don't climb and the possums are too light to do much damage. Also being off the ground allowed me to easily clip the wires along the wood frame. The panels are off the ground to stop them climbing on them and to ensure that I don't have to keep brushcutting the grass that is in front of them too often.
There are trees and bushes behind the water tanks to the West and South (which is where our strongest wind comes from) We regularly get winds up to 100 klm in winter but our house and where the panels are is protected a bit.
I usually over build, I only want to do a job once if possible.
Hi Doc , I just saw your post. Yes I did think about that, but I have enough storage space and yep I basically built it to the standard a small building would have.The rocks are so big here that pulling one out of the ground required a winch, and a friend levering it up at the same time. Some of the post holes had to be moved a bit to miss rocks that I could not get out. The joys of living on a Granite mountain. We love it here and are not planning on leaving, except in a box
Cheers
Pete
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Offline lighthunter

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Re: No brand/5500W inverter disaster porn
« Reply #69 on: June 27, 2021, 10:51:20 am »
Good morning guys, I wanted to update the solution i had questions on in post 63 "string of various brand panels running wrong max power point for the mppt channel" The grid tie mppt channel was targeting 428v at 3-4A. The whole inverter was maxing out at 3200w in full sun with two strings. (the other string output normally runs 1750w by itself)

A week ago i got a new grid tie inverter and needed to test it to make sure i didnt get a lemon. So i moved the low amp problem string to the new inverter and wow what a difference. String volts went to about 400 and output from that string alone was more than both strings were putting out on the other inverter. This at 10:30 am with a 30 deg light angle err.
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Offline lighthunter

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Re: No brand/5500W inverter disaster porn
« Reply #70 on: June 27, 2021, 11:14:16 am »
No doubt cloud edging was involved with that kind of power
because i think the panel string only
adds up to 4kw.

In addition the other inverter was still running other string at 1350w.

So thats a pretty big improvement by switching mppt volts.

Like i said, those numbers hardly add up, (why i attached photos) im sure later today when the clouds clear and it heats up the numbers will be more realistic but the point is, an mppt can choose the wrong numbers and its worth a check. Ive no doubt the other inverter has nothing wrong with it. It just somehow chooses the first power peak it sees without sweeping the range.
While troubleshooting I thought maybe im overloading it causing it to choose an incorrect voltage to manage power but no sir, i even removed the other string and removed a few panels from string. The real problem of course being mismatched panels but sometimes thats all weve got to work with.
All in all was very happy with result and happy inverter worked!
 
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Offline lighthunter

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Re: No brand/5500W inverter disaster porn
« Reply #71 on: June 27, 2021, 11:55:44 am »
 Those numbers are wonky. I knew something was up but still very confused why they would display REACTIVE power on a grid tie display meter rather than REAL power. evidently, this is one of those fancy power factor correcting inverters and it doesnt like my phase angle and is trying to correct it...

I thought of deleting the previous posts out of embarassment but maybe its good for humor.... or drama.... if your into that kind of thing. So am waiting for the clouds to clear so i can measure current and volts of the array to give me actual real power HA!
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Offline lighthunter

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Re: No brand/5500W inverter disaster porn
« Reply #72 on: June 27, 2021, 12:18:25 pm »
These are the ACTUAL values, seem to agree with my clamp meter too.  So 398v x 9.5A = 3781W from the array. The rated stamped values are 16 panels 5x250w + 5x200w + 5x245w +
 1x320w= 3795w rated and 10 of those panels are 5 yrs old.
Still illustrates the mppt tracker on the other inverter was a problem. Not the only one of course.

The power meter on the new inverter sure is misleading. What are they tryin to impress somebody??? Yeah yeah sure fooled me ::)

Oh well as long as it works and hey it can correct all the problems it wants with the power im all for that!!

Cheers hope everyone is doing well!!
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LH

Offline Pete

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Re: No brand/5500W inverter disaster porn
« Reply #73 on: June 27, 2021, 05:51:30 pm »
Good to hear that you have sorted it out. Seems that creative accounting spreads to other situations too.
I guess that the manufacturers are trying to copy Volkswagen and fudge the figures to sell more inverters.
Cheers
Pete

Offline lighthunter

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Re: No brand/5500W inverter disaster porn
« Reply #74 on: August 12, 2021, 06:54:58 pm »
Update,   there has been a bit of discussion about disabling the overcurrent protection on the egs002 board (which is used on this inverter).  The reasons for disabling were to do with poor shutdown control when triggered sometimes resulting in blown FETs. The disable procedure i think went something like, remove 393 SOT and jumper pad 1 to 4 and short  pads 7 to 8.

If you find that procedure difficult to maneuver and really dont want anything to do with current limit there is an option. Just snip or break pin one (IFB) off of the egs002 board and plug back into its edge connector taking care to line up with original hole positions and your off to the races, no overcurrent trouble to worry about, use fuses or breakers.

Why do i know this and why did i do it? 

The voltage feedback uses isolation transformer which insulates control circuit from any ground loop problems that might influence the sensitive voltage control circuit. If you omitted the tiny Vfb isolation transformer you would have all kinds of miserable problems.

The IFB doesnt have a means of isolation, (though you could make one) my system developed a problem where the overcurrent protection would trip out at random. When this happend it would shut off power to the house and my controller would switch to grid then after 16 sec the inverter would start up and do it all again. There is a small delay like 44/100 of a second for an unplanned power failure transfer this of couse isnt friendly to some appliances. Too much info i realize but you get the point. Having your main battery inverter switch off randomly through the day isnt good. I tried figuring out the real source of the problem, finally thought i nailed it when i noticed it occured instantly when relay contact closed for array 1 to grid tie 1. Great i thought now i have it cornered. Very little rain this summer but i noticed this problem only occured after a rain. So i grab a meter thinking the array has high voltage leaking. A 10mohm input meter showed 6v max of leakage between either hv terminal to ground. Scratching my head i thought, i dont need the power right now, ill just leave the array unplugged. Believe it or not that afternoon the inverter did it again even with the offending array unplugged. So id had enough, had wasted a good 4 hrs, had pulled new wire in underground conduit to the array etc. Shut power off to everything, removed board busted pin off, plugged back in and hasnt been a problem since. I might do something with an optoisolator later but for now i like it. I dont think overcurrent shutdown ever saved mosfets from a screwdriver across the output leads anyhow but could be nice if you use yours to capacity. Mine usually only runs at 1/2 capacity.

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LH