Cabling for Controller to Battery and battery to Inverter

[paulcheung]

Maximum solar input voltage, according to the specs in the manual, is 150V dc. My panels Max output is only 1280W, and this CC is capable of handling 3200W.

Voc , from the spec label on the panels, is 21.6.

As previously posted, this CC is brand new and replaced an eight year old Xantrex C40 PWM model, which never presented this sort of problem! Beginning to suspect something very wrong with this new CC!

How are these panels wired? in series or parallel? how many in one series if in series?

[Sunking]

Panel Voc is 21.6. and maximum output for the 16 x 80w panels is only 1280w. Thus all within spec of the CC - it's specs say Max solar input voltage 150V and max input power 3200w. Thus if the CC is going into OVD because of PV input, then clearly there is a problem with the CC, not the panels, which worked perfectly for over eight years when connected to the old CC - a Xantrex C40 PWM.

Nice and sunny today so around noon will connect my DVM to check battery voltage when the CC goes into an OVD. I understand from your advice that if battery voltage increases to the OVD level then the CC is not regulating properly?

It does not matter if the controller is shutting down from input or output over voltage trips. If the panel input Voc is below the specified maximum (Roughly 120 volts or less from the panels to a 150 volt controller) for the controller, or if the controller output voltage exceeds battery voltage, then there is no question the controller is faulty as everything is working within specified working limits. That is unless you have a wiring, or configuration problem.

Now with said with 16 x 80 watt panels there is a good probability of wiring problems on the input, but no input wiring problem should cause the controller to over voltage the batteries, unless the controller fails and connect the controller directly to the panels which is a common Failure Mode when the FET shorts out that connect input to output. This is one reason why we use over current protection.

[Sub]

There are two important characteristic voltages associated with a panel:

Your CC must be able to safely handle the Voc voltage of your string of panels. The fact that during normal operation the voltage may be lower is not enough to keep the CC safe.
Your CC will take a varying amount of power from the panels depending on how low the battery is and therefore how much current it can accept.
If the battery state is such that the CC will use less than the maximum panel power, then an MPPT CC will draw less current and let the panel voltage rise from Vmp toward Voc.

That is one potential reason for an OVD indication, if it refers to the input from the panels.

If the OVD indication comes from reading too high a voltage at the battery, then it is an indication that the CC is not regulating the charge current correctly and/or the connection between the CC and the batteries has too high a resistance or an inconsistent resistance (bad connection.)

Panel Voc is 21.6. and maximum output for the 16 x 80w panels is only 1280w. Thus all within spec of the CC - it's specs say Max solar input voltage 150V and max input power 3200w. Thus if the CC is going into OVD because of PV input, then clearly there is a problem with the CC, not the panels, which worked perfectly for over eight years when connected to the old CC - a Xantrex C40 PWM.

Nice and sunny today so around noon will connect my DVM to check battery voltage when the CC goes into an OVD. I understand from your advice that if battery voltage increases to the OVD level then the CC is not regulating properly?

[Sub]

Voc

May be the CC is triggered by maximum input voltage instead the output voltage. what is the maximum input voltage for this CC? and what is the VOC on these panels?

Maximum solar input voltage, according to the specs in the manual, is 150V dc. My panels Max output is only 1280W, and this CC is capable of handling 3200W.

Voc , from the spec label on the panels, is 21.6.

As previously posted, this CC is brand new and replaced an eight year old Xantrex C40 PWM model, which never presented this sort of problem! Beginning to suspect something very wrong with this new CC!

[inetdog]

I have no technical training, but it seems odd to me that the CC will go into OVD just because the sun is shining brightly. Being familiar with the regulator on my car, I would have thought that it is the CCs job to regulate incoming voltage from the PV to prevent battery overload. It seems too that this CC (eTracer 60A) is a bit of an odd one out, in that most do not have programmable OVD etc settings installed (according to the advice from our local installer). Also,it seems the CC is going into OVD in response to high voltages coming from PV rather than high voltage in the battery bank.

There are two important characteristic voltages associated with a panel:
1. The open circuit voltage, Voc. This will be more or less independent of the amount of light shining on the panel and will basically depend on the number of cells in series that make up the panel.
2. The maximum power voltate, Vmp. This will be about 80% of Voc and will also be more or less independent of the amount of sunlight.

Your CC must be able to safely handle the Voc voltage of your string of panels. The fact that during normal operation the voltage may be lower is not enough to keep the CC safe.
Your CC will take a varying amount of power from the panels depending on how low the battery is and therefore how much current it can accept.
If the battery state is such that the CC will use less than the maximum panel power, then an MPPT CC will draw less current and let the panel voltage rise from Vmp toward Voc.

That is one potential reason for an OVD indication, if it refers to the input from the panels.

If the OVD indication comes from reading too high a voltage at the battery, then it is an indication that the CC is not regulating the charge current correctly and/or the connection between the CC and the batteries has too high a resistance or an inconsistent resistance (bad connection.)

[paulcheung]

May be the CC is triggered by maximum input voltage instead the output voltage. what is the maximum input voltage for this CC? and what is the VOC on these panels?

[Sub]

Is it a problem with the CC?

When you get your digital multimeter, the first thing to do is measure the voltage directly on the output terminals of the controller. Also measure the voltage directly on the input terminals of the inverter. And measure the voltage directly on the battery terminals.

Try to do this under several conditions:
It would be good to know those numbers when the system is relatively at rest (at night with minimal load).

Also get those numbers while there is strong solar charging (it would be nice to get the measurements when the OPD event occurs, but for the purpose of this troubleshooting, it is not necessary.)

And finally, get those numbers with a heavy load (run the microwave at night while you take themeasurements)

If you can get these measurements, that would be a very good first step in troubleshooting your problem.

In the meantime, you can do a visual inspection of all connections. If you have an infrared thermometer, you can look for hot spots... you must do this when there have been strong currents (charging and/or discharging) for awhile. You can also re-torque connections. It wouldn't hurt to disconnect the battery cables and clean the battery terminals and cable connectors.

--mapmaker

1. It took a couple of weeks for the new digital multimeter to arrive. So, I visually checked all joints, put my hand on connection points, no kinks and no heat detected. Became increasingly concerned about frequent OVDs when sun shining brightly. Contacted my nearest solar installer hoping he could trouble shoot things for me, but he is reluctant to work on other people's installs - also probably a bit annoyed I didn't purchase through him. He did say two things; firstly that on his installs he always uses one set of cables for to and from the battery bank - thus disagreeing with the supplier's opinion that the inverter and controller should not share the same cables to the battery! Secondly, that he had never heard of a CC having OVD.

2. That comment made me think, so went back to the Operation manual for the CC, and also for the Inverter. Yes, the CC definitely has settings for OVD, also UVD. So does the Inverter, which I found is preprogrammed to work between 42V and 62V, thus performing an OVD at 62V. The CC default setting for OVD was 64V and default for Charging Limit was 62V. The CC and Inverter voltages did not seem compatible, so I experimented with lowering the OVD and Charging Limit settings on the CC finally settling on 61.1V for OVD and 60V for charging limit. I also slightly lowered the setting for Absorb from 58.8V to 58.4V.

3. Now when sun shining brightly, the CC still goes into OVD at around 61V but the inverter does not, which means power supply to the house does not get interrupted.

4. On the same day as 2 & 3 above, my new digital multimeter arrived. I have been taking measurements at several times;

(A). At 7.30am before sun over horizon, voltage from CC out was 50.9; at battery terminals 50.9; at Inverter input 50.8.

(B) at mid morning CC out 55.4; batt terminals 55.4; at inverter 55.3.

(C) at about 1pm straight after the CC went into OVD, - CC out was 59.1; batt terminals 59.1; at inverter 59.

At the time the CC went into OVD I was watching the analogue voltage meter. It was a time of lovely bright sun. The needle rose rapidly from 56V to over 60V (the Max reading is 60V), then as the CC went into OVD the needle just as rapidly dropped to 56V. For the next few minutes, while the sun was unobscured, that sequence continued to cycle. Rising from 56 to over 60, OVD occurring, and dropping back to 56. I assume if the sun had continued to shine brightly that process would have continued.

I have not yet performed voltage tests at night under load, nor been able to perform a system at rest test - still waiting for consistently settled weather when I will disconnect charge and load around midday, leave for four hours before testing.

Was the initial problem (the inverter going into OVD) caused by incompatible OVD settings on the CC and Inverter? Or, is there a fault with the CC?

I have no technical training, but it seems odd to me that the CC will go into OVD just because the sun is shining brightly. Being familiar with the regulator on my car, I would have thought that it is the CCs job to regulate incoming voltage from the PV to prevent battery overload. It seems too that this CC (eTracer 60A) is a bit of an odd one out, in that most do not have programmable OVD etc settings installed (according to the advice from our local installer). Also,it seems the CC is going into OVD in response to high voltages coming from PV rather than high voltage in the battery bank.

Look forward to reading your opinions re the above, and in meantime will carry on with checking with my multi meter when weather conditions permit.

I checked the Monitor on the CC just now and watched as it performed an OVD. The monitor showed battery voltage as 59.1 and PV voltage as 88.9. I am a bit confused by the PV voltage, as if anything I thought my array was a bit small for my new battery bank, being 16 x 80W panels, thus only 1280W total. Installed by previous owner who told me they are wired to produce 48V. So do not understand how they can output nearly 90V?

Another thing about the CC concerns me. Only twice, in just over two months it has been installed, have I seen it reach Float. The CC is programmed to Absorb charge for two hours, then I assume it should go to Float?

[Sub]

Thanks, Mapmaker



The battery cables are 15mm in diameter (which I think equals AWG 0000) so should be thick enough.

I have asked my daughter's partner (who owns a large electrical business) to send me a new digital voltage meter, so will do the checks you recommend when it arrives. Will post result. If any thing needs fixing will call in an expert to do it.

Thanks for your patience with someone who has limited technical expertise!

Fortunately the tree fell on the south side of the house so missed the solar water heating panels on the north side of the roof. No room for PV panels on roof so they are on a sturdy platform about 40 meters from the house. Some people did lose PV panels in the storm - someone not far from us had reportedly $25K worth of solar ripped off by the wind. And separate from the storm, worryingly, a neighbour about 2 kilometres up the road from us had their solar system stolen last week while they were away.

[mapmaker]

Just had another read of the controller operation manual, and apart from saying there is an optional cable available for connecting to the remote battery voltage port, nowhere does it say what it is for! Which raises the question, should I have one?

Quite a storm! Hope the falling trees didn't hit your solar array.

If you have proper cabling, you don't need a remote voltage sensor. 'Proper' means thick enough that there is insubstantial voltage drop across the cable.

The reason I was asking is because if you have a remote voltage sensor installed, that could be contributing to your problems. My best guess about your problems is that you have a bad connection somewhere in the power wiring. It could be a bad crimp in a cable. It could be almost anywhere, but I suspect it to be in the battery cables and/or shared wiring of the inverter and controller.

When you get your digital multimeter, the first thing to do is measure the voltage directly on the output terminals of the controller. Also measure the voltage directly on the input terminals of the inverter. And measure the voltage directly on the battery terminals.

Try to do this under several conditions:
It would be good to know those numbers when the system is relatively at rest (at night with minimal load).

Also get those numbers while there is strong solar charging (it would be nice to get the measurements when the OPD event occurs, but for the purpose of this troubleshooting, it is not necessary.)

And finally, get those numbers with a heavy load (run the microwave at night while you take the measurements)

If you can get these measurements, that would be a very good first step in troubleshooting your problem.

In the meantime, you can do a visual inspection of all connections. If you have an infrared thermometer, you can look for hot spots... you must do this when there have been strong currents (charging and/or discharging) for awhile. You can also re-torque connections. It wouldn't hurt to disconnect the battery cables and clean the battery terminals and cable connectors.

--mapmaker

[Sub]

[QUOTE=mapmaker;117351]The purpose of the "Remote battery voltage sensor port" is NOT for you to measure voltage at that location. It is for a pair of wires to run to the battery so the controller knows the battery voltage through a means other than the power cable.

--mapmaker

Oops, a case of split focus by me - very busy at moment clearing up after a once in 60 year storm, 510mm (just over 20") of rain in three days, gale force winds, non stop rain for five days, already had a lot of rain earlier in the month, ground sodden and the gales uprooted six large trees, one of which landed on my house. Two other large trees snapped off about head level. We live on a hillside 150metres above sea level, but many parts of the region suffered major flooding. We were cut off several days with washouts and slips on our road, and telephone service out for 7 days. The region without grid power for ten days. Have had 8 days of fine weather since, so very busy clearing up. Have large stack of wood from only two trees to split up for firewood, and still six trees to go!
Plus I should now be building the deck and installing French doors on the sunny side of my house ready for summer, and having the distraction of the new battery bank and controller not performing, has been getting in the way.

So, I made an assumption that the remote voltage port was for the voltage meter, just had a close look, and the cables for the voltage meter are in fact wired into the controller sharing the outlets from controller to battery.

Sorry to alarm you! Just had another read of the controller operation manual, and apart from saying there is an optional cable available for connecting to the remote battery voltage port, nowhere does it say what it is for! Which raises the question, should I have one?

[mapmaker]

There is an outlet on the controller named "Remote battery voltage sensor port". I have an analogue voltage meter connected to that. The meter sits beside the inverter by my back door. I know they are not as accurate as a digital meter, which is why I am researching battery monitors, and will buy one of them soon.

The purpose of the "Remote battery voltage sensor port" is NOT for you to measure voltage at that location. It is for a pair of wires to run to the battery so the controller knows the battery voltage through a means other than the power cable.

If there is bad connection between the controller and the battery (in the power cable), the battery will not see all the volts that the controller is making. If the controller has battery sense wires, it will see that the battery is at lower voltage than the controller's output, and the controller will keep raising its output voltage in an attempt to raise the battery voltage that it measures through the sense wires.

--mapmaker

[Sub]

Does your controller have voltage sense wires?

--mapmaker

There is an outlet on the controller named "Remote battery voltage sensor port". I have an analogue voltage meter connected to that. The meter sits beside the inverter by my back door. I know they are not as accurate as a digital meter, which is why I am researching battery monitors, and will buy one of them soon.

At time of OVD events the analogue meter, which only goes to 60V, was off the scale, but it does that regularly at times of good sun, even on my old battery bank and the old PWM controller with no adverse effects.

No OVD so far today even though we have good sun, the only difference from the other days is the controller now says Charge Mode is "Floating", whereas before it was on "Absorb" - don't know if that would make a difference?

In the meantime I will do some testing when my new voltage meter arrives.

[mapmaker]

The batteries are new, but could a "bad" battery cause this sort of thing? My voltage meter has died and I have a new one on order, so will check individual batteries when it arrives.

Yes, a bad battery could cause it, but my best guess is a bad connection.

I suspect that the voltage that the inverter sees is NOT the same voltage that the controller sees. That's why I asked how/where you are measuring the voltage. The voltages on the battery should be measured, but I really think you need to measure the voltage on the inverter input terminals at a time of OVD. I predict it will be higher than the voltage you read on the controller screen. Does your controller have voltage sense wires?

--mapmaker

[Sub]

OVD is that fault on the INVERTER or on the CONTROLLER

I had a high resistance wire that nearly smoked my ePanel, and my first indicator was high battery voltage sensed only by the charge controller.

On the Controller.

Re your questions in previous post, the readings I quote are from the LCD monitor on the controller.

When it goes to OVD everything shuts down, hence no power to the inverter, and the inverter "beeping" happens when power is restored. The OVD shut down only happens for a few seconds at a time, and it would have taken me a while to realise what was happening, except I happened to be standing in front of the controller when it went into OVD.

The controller monitor also has a read out for minimum and maximum voltages for the day - when I checked that after last OVD shutdown, it read, min 50.6V and max 62.2V, and since the OVD setting is 64V that does not compute in my head!

I will try and get a wiring diagram, or if I can work out how to post a photo that will show how things are wired up.

The batteries are new, but could a "bad" battery cause this sort of thing? My voltage meter has died and I have a new one on order, so will check individual batteries when it arrives.

[Mike90250]

OVD is that fault on the INVERTER or on the CONTROLLER

I had a high resistance wire that nearly smoked my ePanel, and my first indicator was high battery voltage sensed only by the charge controller.