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
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.
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.
Thank you - I will try P&O mode for now and report. Forcing bulk or absorb does not seem to bring the charge on.
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.
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
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.
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 :)
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
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?
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.
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.
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
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.
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.
Did you say which firmware version your Classic has ? I looked though all the previous posts but didn't see it or I missed it.
Larry
The latest. As far as I know there is nothing after 2126
Quote from: Westbranch on November 17, 2017, 12:14:30 PM
...a back-feed situation and damage , in your system , to the whole ARRAY....
hi, why would a string of 3 panels spontaneously "back feed"? The Array seems happy to deliver enough power to the capacity of the classic, eliminating the possibility that the array is damaged. Also there is no evidence of physical damage, so not sure what you mean by a series of panels (3) "back feeding".
Quote from: NoPowerBills on November 17, 2017, 07:31:14 PM
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.
Hi N P B,
Thanks for the PV info, here is a Link to the complete date on those:
https://www.enfsolar.com/pv/panel-datasheet/Monocrystalline/5003
These PVs should be fine as far as minimum string Vmp is concerned for strings ot three. Just run the Classic Sizer with all of that data, and look at the Vin for your lowest temperature of record for your site ...
As was noted before, you must run the Classic Firmware and the MNGP versions that are compatible. Please let us know what is your MNGP FW Version #.
Believe that Down Under, an "isolator", is a DC relay ?
The DANGER in not running a real Combiner with a DC breaker for EACH PV string, is that if one PV develops a Fault, like a short, that as many as six other strings can run its Isc rating into that one PV. This could be as much as about 42 Amps combined into that one PV. This can easily cause a FIRE.
No time now, gotta get to work. FWIW, Vic
Vic, thanks for answering that much more simply than I could.
ej
Quote from: Vic on November 18, 2017, 11:53:34 AM
As was noted before, you must run the Classic Firmware and the MNGP versions that are compatible. Please let us know what is your MNGP FW Version #.
Hi, From the Status App:
- Classic Rev: 2126
- Network Rev: 2097
So the MNGP will be the latest, it's all embedded in the one download - 2126. And both the Classic and the MNGPw were updated in the same session.
Point taken about the combiner - if 3 panels in series fail/get damaged, there could be a "backfeed". But since this is not happening now, can we leave that as a future project and not the cause of these weird non-start days? BTW the maximum current in such a situation would be closer to 27A (ie. string of 4, one fails leaving 3 at Isc - right?)
Thanks for the info though.
N P B in 'the normal situation, where there are more than 2 panels in series' you would have 0ne breaker for each string of 3 PVs and the 'connection' would be in the combiner box. It only takes out 1 bad panel to cause a back feed... in the normal setup that would eliminate 3 panels total..., the one that failed and 2 more that were in that string....
However the way you have connected it, 1 shorted PV , has the potential to Kill off all your PVs and probably cause a serious fire...
Quote from: NoPowerBills on November 18, 2017, 04:37:51 AM
The latest. As far as I know there is nothing after 2126
Not that you need it but the new talking version of firmware is out there in beta form though seems to be just fine
2154 6/26/17 MNGP
2151 5/26/17 Classic
2122 network
Larry
Since nothing else has worked it may be worth trying this F/W. Where to find it? Nothing on the Midnite site:
http://www.midnitesolar.com/firmware.php?firmwareProduct_ID=1
Quote from: NoPowerBills on November 28, 2017, 02:38:51 AM
Since nothing else has worked it may be worth trying this F/W. Where to find it? Nothing on the Midnite site:
http://www.midnitesolar.com/firmware.php?firmwareProduct_ID=1
Instructions and links are in the document in the first post of topic below -- Voice Beta .docx
http://midniteftp.com/forum/index.php?topic=3746.0
Larry
Thanks Larry, no way would I have found that on my own!