UPDATE:
So far so good and since replacing the fuse holder, fuse #3 has not blown again.
ANOTHER ISSUE:
Inverter 2 runs hotter than inverter 1. Reminder this is grid-tied system
with 2-GVFX3648’s in series for 120/240V. The fan on inverter #2 had
malfunctioned, but I was able to replace it and get that going again. Even
with the replaced fan, inverter #2 is still running noticeably hotter. My
understanding is that both inverters in this system are essentially “Masters”,
since this is grid-tied. Shouldn’t the load/generation be split between the
two and hence they run equally as hot? I did check the stacking and they were
both set to “Master” which is I think what they recommended for grid-tie. I
tried switching the ports on the Hub that they are plugged into to see if that
would change anything, but no change. I did also noticed while I was there
last week that while both inverters had the solid yellow “AC IN” light on,
inverter #2’s green “Inverter” light was always on, while inverter #1’s green
“Inverter” seemed to come and go…
Any ideas?
Thanks as always,
Amos
Amos Post
Integrity Energy
W 802.763.7023
C 802.291.2188
ienergyVT.com <http://www.ienergyvt.com/>
Facebook <https://www.facebook.com/integrityenergyllp?ref=hl>
> On Apr 15, 2025, at 8:40 AM, Amos Post <[email protected]> wrote:
>
> Hi all,
>
> I decided to start with the simple stuff. While I don’t have a string curve
> tester (I should have one), yesterday I tested strings 1,2,3 individually
> under load. String 3 is the one that’s been blowing the fuse. I did not
> test strings 4-6 which are on a separate charge controller and combiner.
> Here are the results:
>
> String 1- 7.1A at 76V
> String 2- 7.77Aat 79V
> String 3-7.13A at 78.3V
>
> I did notice that the second charge controller with strings 4-6 was running
> about 100watts more (1800w vs 1700w). The conditions were clear blue skies.
> I replaced the fuse holder and fuse. If it blows again I’ll try switching
> strings to see if it follows…
>
> Thanks for your feedback and I’ll keep ya’ll posted.
>
> Amos
>
>
> <IE LOGO 150x78.jpg>
>
> Amos Post
> Integrity Energy
> W 802.763.7023
> C 802.291.2188
> ienergyVT.com <http://www.ienergyvt.com/>
> Facebook <https://www.facebook.com/integrityenergyllp?ref=hl>
>
>> On Apr 11, 2025, at 4:07 PM, Jerry Shafer via RE-wrenches
>> <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>> Wrenches, Amos, blowing of a 15 amp fuse is not a ghost in the machine, it
>> is an actual issue no way around it, shorted modules, shorted diodes, in
>> most cases it's a home run, way back when USE-2 white wure was failing and
>> would crack and break off mostly this would result in a GFI trip. The fuse
>> is blowing because of over current and a single string of your vintage will
>> max out at far less than 10 amps but the other two strings will back feed
>> this fuse with close to 20 then pop.
>> Sharp had module failures resulting in cell shorts, look very close there. I
>> have inspected arrays with extreme exposure differences, this will effect
>> performance but should not pop a fuse. Do you have a module string curve
>> tester, this very well may show an issue of the string but eyes on the array
>> is required to located the cause.
>> I have seen nails through wires, conduit, racking in contact with the back
>> of the module but this will trip the GFI breaker not the string fuse.
>> Fun times.
>>
>>
>> On Fri, Apr 11, 2025, 12:49 PM david quattro via RE-wrenches
>> <[email protected]
>> <mailto:[email protected]>> wrote:
>> One time I had similar, but different problem: 1 Amp ground fault fuse
>> consistently blowing, sometimes after 1 day sometimes after weeks/months. I
>> tried everything - replaced home runs, checked VOC, VMP, swapped DC input
>> into a different inverter, etc. it kept coming back to this one string. I
>> checked every module VOC, ISC, every connection, no pinched wires, no
>> discernible problem, but fuse blowing.
>> Luckily it was a medium size commercial job (on a fire station) so I was
>> able to scatter all the modules of this suspect string all over the roof,
>> and carefully track where I had put them. That’s when the problem went away
>> and never came back..😂
>> Best I could figure was a slight manufacturing error that had a
>> compounding/cumulative effect. So once I got those consecutive serial
>> numbers away from each other no more problem. Either that or the fire chief
>> was fucking with me and he was burning out the fuses, which I doubt
>>
>>
>>
>> On Fri, Apr 11, 2025 at 8:05 AM Mac Lewis via RE-wrenches
>> <[email protected]
>> <mailto:[email protected]>> wrote:
>> Hello Amos,
>>
>> Have you checked for voltage imbalance for each string? If you have a bad
>> diode, that string may run low on voltage and be trying to send current
>> toward the weak string (this is the reason you have these breakers). I'd
>> run each string independently and see what Vmp is. If you are missing some
>> voltage that may be a clue. You can also independently clamp each string
>> during operation.
>>
>> I like IR cameras for this type of thing. It may just be a bad connection,
>> heat build up, fuse holder issue.
>>
>> Let us know what you find out
>>
>> On Fri, Apr 11, 2025 at 8:07 AM Amos Post via RE-wrenches
>> <[email protected]
>> <mailto:[email protected]>> wrote:
>> Hi Wrenches,
>>
>> I have a bit of a puzzler that I’m trying to get sorted out. I’ve been
>> servicing a Grid-Tied Battery Backup system that’s about 17-18 years old.
>> The system comprises of 2-GVFX3648s in series, with 2-MX60(at least I think
>> they are 60s) CC’s. Each CC has 3 strings of 3 tied to it, and each string
>> has a 15A in-line 600V fuse. The modules are I believe are like 230/240Watt
>> 60 cell modules (sorry I don’t have pictures/specifics). We replaced the
>> flooded batteries with AGMs about a year and a half ago.
>>
>> The situation is one of the 15A string fuses keeps blowing. It’s now
>> happened 3 times and its the same fuse every time. First we just replaced
>> the fuse and under the surge/lightning assumption. Fuse blew again. Then I
>> thought I found the culprit. The #6 PV output from the combiner to the PV
>> input breaker for the CC was a bit darkened and very warm to the touch when
>> I replaced the fuse the first time. So I though maybe it was a loose
>> connection on that lug and that caused everything to heat up and eventually
>> blow the fuse. I cut and stripped the wire back and cleaned the lug and
>> re-seated the wire in the lug. Fuse blew again within a few months time. I
>> then checked the Junction box on the roof where the USE-2 wire connects to
>> THHN, and did a visual inspection of all the wiring on the roof. All of the
>> Jbox connections and everything on the roof “looked” ok. I have also check
>> all of the connections inside the Outback DC load center, and they look ok.
>> Fuse replaced 3rd time and then it blew again.
>>
>> Before I take all of the panels off the rack, check panels, re-check string
>> wiring on the roof, is there anything else I should be checking? Seems like
>> that warm wire in the Combiner box is telling me something but I can’t
>> figure out what...I believe this is a new problem in the last 2-3 years but
>> we are not 100% sure when the problem first came up…
>>
>> As always, thanks for your help/ suggestions!
>> Amos
>>
>>
>> <IE LOGO 150x78.jpg>
>>
>> Amos Post
>> Integrity Energy
>> W 802.763.7023
>> C 802.291.2188
>> ienergyVT.com <http://www.ienergyvt.com/>
>> Facebook <https://www.facebook.com/integrityenergyllp?ref=hl>
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>> "Yo solo sé que no sé nada." -Sócrates
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