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torrmundi avatar image
torrmundi asked

MPPT not working?

Hi, I have 4 MPPTs regulating 4 panels in a nearly flat array. Today, full sunlight and wildly different charging:

No1: 310 WH, bulk mode, 7 amps

No2: 0 WH, bulk mode, 0 amps

No3: 250 WH, bulk mode, 1-5 amps

No4: 350 WH, bulk mode, 6-8 amps

No2 has not given more than 10 WH in a day since 10 days ago. 12 days ago it yielded 390 WH.


Solar: four of Kyocera KD140GX-LFU, Pmax 140watts, Voc=22.1vdc, Isc=8.7A, Vpm=17.7v, Ipm=7.9A, all panels mounted skyward on salon roof.
Regulation: four of Blue Solar MPPT 75/15 regulators, firmware v1.46
Batteries: three of Lifeline GPL-4DL AGM batteries, 210 AH each
No loads are connected to any regulator.
Line losses to Batt terminals can be 1.0 volts or more at full charge rates.
Smart Battery Sense installed.
MPPTs are networked via Smart Bluetooth Dongles (Rev2).
Magnum Energy shunt and battery monitor (not connected with Victron).


When will there be a synced MPPT network for Blue Solar 75/15 devices? Version 1.47 is not released for 75/15.


MPPT Controllers
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3 Answers
JohnC avatar image
JohnC answered ·

Hi @torrmundi

I can't answer your specific 'when' question. In this case I'd enter troubleshoot mode to try to narrow down your issue.

Try 'denetworking' them and confirm that each is performing as it should, totally alone. In Bulk mode preferably to see what each can do, even if you need to shut down the others or add a load to get it maxing W in Bulk.

Your panel V is also close to batt V, and the difference there in practice is worth noting.

Come back..



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torrmundi avatar image
torrmundi answered ·

I tried turning all "Charger Enabled" off except #2 and noticed that the Vb was above 14 volts (my battery was about 12.6v at that time). I immediately thought of a loose connection to the battery wires so I took a look at the charger wiring. Guess I need to do a thorough cleanup here. Is it ok to let the panel go high open circuit voltage without any load? (I googled this and the answer is OK for open circuit).


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Justin Cook avatar image Justin Cook ♦♦ commented ·

@torrmundi, I'm seeing case deformation in this MPPT; I'd very strongly suggest replacing that unit entirely given at this point, given that we can't be sure what kind of damage could be caused to the internal components on this unit.

It is okay to let the panel go VOC, but of course be extraordinarily careful when handling those wires if you don't have a fuse or breaker on the PV side to be able to isolate the controller. The PV wires will be live, of course, so I recommend that you either cover the panel that's feeding this unit or disconnect the MC4 connections or, at the very least, completely insulate each of the PV wires with either wirenuts or electrical tape or something of that nature when you remove each one from the MPPT.

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torrmundi avatar image
torrmundi answered ·

@JohnC I cleaned up the connect with a diamond file and got it looking electrically clean (just not pretty). After reconnection, I've had 80WH yield. The Vbatt is almost identical to my battery monitor reading at low currents, so I feel happy about that. It is also similar performance to the panel next to it.

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hi @torrmundi, Please do not use that MPPT anymore, it is not safe!! Also, please let an electrician check your system. loose connections can cause fire. I noticed on the PV connection (positive) there are also signs of heat and corrosion. use clean cables, with ferrules and don't hesitate to use a little (!) bit of electrical grease to prevent corrosion.

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torrmundi avatar image torrmundi Daniël Boekel (Victron Energy Staff) ♦♦ commented · 
@Daniël Boekel please outline the risks that cause you to declare this regulator as unsafe.  In addition, can you explain what safeguards are designed into the Blue Solar regulators to avoid over-temperature and to avoid fires if overtemperature occurs? <BR> I expect that many MPPTs operate at very high temperatures in hotter climates, and may be installed in areas with little or no ventilation.  <BR> Your direction to use ferrules is not in the installation instructions for the Blue Solar / Smart Solar regulators. Nor does ABYC require them or even recommend them, AFAIK, when using stranded conductors with compression plate type connectors (as used in Victron MPPTs). <BR> I did look up this subject, and found that CE regulations require them in some applications.  Apparently the compression of the ferrules removes oxygen and prevents moisture ingress over time, lowering the contact resistance over a period of years.  I think the use of an electrical grease is well founded. ABYC regulations, see https://www.proboat.com/2016/09/terminal-connector-compliance/


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Justin Cook avatar image Justin Cook ♦♦ torrmundi commented ·

@torrmundi, there are scorch marks at the terminal and there is significant case deformation on this controller - it would be highly irresponsible for anyone to recommend that you continue using it. Once the case has literally deformed from the heat caused by a loose connection, it is impossible to tell what other damage may have been caused internally. Please replace the unit.

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