Midnite Classic 150 produces no power whilst in Solar / Bulk Mode

Started by NoPowerBills, October 18, 2017, 07:47:59 PM

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NoPowerBills

Midnite Classic Rev 4 - FW - Classic 2126 / Network 2097 Arc protection switched off.

On overcast mornings the Classic will show the Mode as Bulk, but be producing no power. Even though there is plenty of power available (ie. panels are sitting at 95v, normal operation under load is 77 - 82) The only way to get the unit charging is by switching the mode "Off", changing to Legacy P&O, switching the mode back "On". Then Revert to Solar Mode. Then normal operation resumes - until the next day.

It only appears to happen when we have a very "soft" start to the day. Ie. There is some fog around and ambient light rises very slowly. But even when we are in full sun, showing Bulk mode there is no charge delivered. There is no partial shading of the bank which is 7 strings of 3 for a total of 5.25Kw. The system works fine where we have a "normal" sunrise - eg. no cloud.

Any help appreciated as this means we can't leave the site unattended.

TIA

australsolarier

the best suggestion i have to you:
leave it in legacy P&O mode. i had similar problems with solar mode. it would cycle from shade to full in a blue sky. suddenly reduce output in bulk mode.
p & o is not without problems, but by far not like p&o mode.
switching between "force bulk" and "force float" often solves faults too.

Sunshine

There are a few reasons this could be happening. If your array is mismatched sometimes it will deliver conflicting data to the Classic, causing a lack of charging. Partial shading on some strings can also be an issue(although you mentioned in your case it is not). As Australsolarier suggested, we would recommend that you try running the Classic in Legacy P&O and see if this allows it to charge correctly. If it does, there is no harm in running your system that way, the only change is it slows down the MPPT sweeps slightly which can have it's own set of advantages. If it does not, we would recommend trying a hard reboot of your Classic(consult the manual or call tech support if you need assistance). If the problem continues after reboot, you would need to call our tech support department to have your Classic repaired.

NoPowerBills

Thank you - I will try P&O mode for now and report. Forcing bulk or absorb does not seem to bring the charge on.

WizBandit

Did you recently upgrade the firmware? If so did you do the mandatory factory reset?

In full sun on the array, turn off the combiner breakers except one string.
Record the Voc and Vmp for that string, turn it off and do the same for all strings, on one at a time only. They should be pretty close on voltage.  Be sure one or more strings are not connected reverse polarity.
What model of combiner box are you using? Has to be the MNPV12 for 7 breakers.

CDN-VT

Agree with WizBandit testing for each string structure .
As for a reboot of the system . Post MNGP & Classic firmware's because they need to match or be of the same flavour for the firmware .

For the REBOOT , turn off all solar & then control from the main classic breaker . Record all /or download all settings with the computer interface.
Do the reboot / reload & see if it works better.

Firmware update for the classic also has a MNPG update on it's firmware !!
VT
Canadian Solar 350W 37.6 VOC  30.6 VMP 8.22 ISC 7.87 IMP ,-15 c +30c max  4 strings in 2 in Series for 24v Classic 150 -1020 Ah  Freezers & fridges ~~~ Second Array same panels of 3sx3 parallel for 24 V Classic 150 -440 Ah Outback Barns & out blds.
48Vdc almost done,11Strings up of 3s11P same panels

NoPowerBills

Quote from: australsolarier on October 19, 2017, 01:00:59 AM
the best suggestion i have to you:
leave it in legacy P&O mode. i had similar problems with solar mode. it would cycle from shade to full in a blue sky. suddenly reduce output in bulk mode.
p & o is not without problems, but by far not like p&o mode.
switching between "force bulk" and "force float" often solves faults too.

Hi, Legacy only made it worse - less inclined to start even on days with a "good" sunrise" The only thing that gets it charging is changing modes and then mod/off/on - or a restart from the GUI. Forcing absorb or Float doesn't work. And yes, it has had a full restart and upgrade to latests F?W. No panels are shaded at sunrise - so it's not a partial shading thing. Hard to believe it's a hardware issue, since a restart DOES make it work.

If we have to send it back for repair we'll have to buy another unit, since we can't be without power for weeks. And if that's the case it is unlikely to be a MIdinite after this.

dbcollen

Midnite has really good customer support, call them and if it needs to be repaired ask them to cross ship you one. They will ship you a new one and you put the old one in the box and ship it back to them. No down time  :)

Vic

Quote from: WizBandit on October 19, 2017, 07:50:10 PM
Did you recently upgrade the firmware? If so did you do the mandatory factory reset?

In full sun on the array, turn off the combiner breakers except one string.
Record the Voc and Vmp for that string, turn it off and do the same for all strings, on one at a time only. They should be pretty close on voltage.  Be sure one or more strings are not connected reverse polarity.
What model of combiner box are you using? Has to be the MNPV12 for 7 breakers.

Hi N P B,

WizBandid  had a great suggestion above.

1.  Have you tried doing those measurements?  What were the results for each string,  please.

2.  Please confirm the FW version for the  MNGP.   What is that version number?

In your first Post,  you note PV input voltage to the Classic to be about 77- 82 V.   This is a bit too low for a 48 V battery bank,   especially if it is cool/cold.   What was the approximate outside ambient temperature when you were seeing the above PV input voltage to the Classic?

Have you run your system configuration through the Classic String Sizer (?):
http://midnitesolar.com/sizingTool/displaySizing.php

Please post the results.   OR  if you are unable to do that,   please give the make and model number for your PVs  ...   are all the PVs identical?

What is the system voltage,
What is the make,   model number for your batteries,  and what is the approximate battery temperature ???

And that you have updated all of your settings since you did the Classic Reset,   after doing the FW Update on the Classic AND the MNGP?

Thanks for all the answers!  Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

NoPowerBills

OK - 21 panels of Earth Sun, 3 in series x 7. The lower voltage mentioned is at sunrise. OC something like 115V, I'll have to check the specs. But at sunrise when the panels have a low angel of sun, the charger is in Bulk Mode but not charging with the Input voltage showing about 95 - 105v at ambient 15 - 20C. The 77 - 82 is what the Classic runs the panels at in MPPT when charging.

Battery temp is irrelevant as we run LiPO4. Float voltage is 58.4 - Bank voltage at sunrise never below 52V. (Same issues when we had PbSO4 - bank voltage never below 48V)

All panels in all strings are the same. No "combiner" used - all parallel connections are soldered. No reverse connected banks. We can see the full potential of the array happening when things ARE charging. Besides it's been like this for 6 years - no wiring changes since commissioning!

All FW is the latest downloaded - I believe there will be no further updates - new product coming?

NoPowerBills

Quote from: dbcollen on November 11, 2017, 10:10:59 AM
Midnite has really good customer support, call them and if it needs to be repaired ask them to cross ship you one. They will ship you a new one and you put the old one in the box and ship it back to them. No down time  :)

Mate, we are in Australia - not US.

Westbranch

you could open a "TICKET" here  http://www.midnitehelp.com and you will probably get Whizbandit...  and as he said you need to check each string individually which means you will need some kind of Combiner Box...

Soldering all the strings together leaves them potentially susceptible to a back-feed situation and damage , in your system ,  to the whole ARRAY....

my suggestion .... add a combiner box.
KID FW1811 560W >C&D 24V 900Ah AGM
CL150 29032 FW V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
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Cotek ST1500 Inv  want a 24V  ROSIE Inverter
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Vic

Hi N P B,

Thanks for the reply and some answers.

First  running 7 parallel PV strings with no Combiner,   can be a FIRE HAZARD.   Strings of three or more PVs  really need a Combiner  and separate DC circuit breakers for each string.   The Combiner also makes trouble-shooting relatively easy.

Thanks for the brand of your PVs,   BUT  without the exact model numbers,  it will not be possible for any of us,   or you to run the MidNite Classic String Sizer,   as noted in the previous link.

Data can be helpful when trying to help diagnose  system performance issues.

When noting PV input voltage to the Classic (CC),   the charge stage for the CC  output power or current at  solar conditions, etc  are important.

Am at a remote site today,  but if you reply with that important data,  we can try to help determine if there may be a configuration issue,   an issue with the CC,   or some other system problem.

I do not yet do any Li battery systems,   but others here can help with that.

Thanks,   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

NoPowerBills

Thanks.

Sorry - I didn't fully understand your question on the combiner. 3 strings run to an isolation switch and then DC breaker. Other 4 strings - isolator - DC breaker.

Panels are: https://www.solarquotes.com.au/panels/sunearth/tpb156x156-72-p-250w.html

As mentioned, on a slow morning (hazy, foggy start) The CC will show Bulk Mode, near Voc - consequently no current, until rebooted or mode changed followed by a mode on/off. A mode on/off does not start the charging.



NoPowerBills

Quote from: Vic on November 17, 2017, 03:10:45 PM
...it will not be possible for any of us,   or you to run the MidNite Classic String Sizer,   as noted in the previous link...   Vic

Ran the tool and the result is fine, 1.1 CCs required - MidNite Solar recommends a second controller be added after 1.2

Minimum working MPPT voltage is calculated at 81v and that's in the ball park of what we see.

Anyway - we've never had an issue not getting enough power in when it IS charging, and the array was speced higher to give more input on cloudy days. None too worried about getting the last watt out on a good day.

Besides we don't want more than 100A going in to the Lithium bank so that's a hard limit anyway. Having a second controller would only give us a 16% boost when the full array potential was available and the bank was ready to accept it - this wouldn't be for more than, say, 15, minutes and rare occurrence. So not worth bothering about trying to get an extra 0.2KW/h for a few days of the year.