Victron 75/50 MPPT system not working!

[themacleanfamily]

Starting to pull my hair out with this one. I'm now on my 2nd of these controllers and still it doesn't seem to be working as it should. I've been offered a MorningStar Sunsaver as a replacement , however before I go down that route i'd be grateful for any advice regarding possible issues with the set up/choice of controller which may be the culprit.
I should say that I am not experienced in this field although I did do a lot of research prior to installing the system on my boat.

Boats electrical system is 24v split across two battery banks. Each bank consists of 4 x 128ah batteries linked to give 24v - Therefore a total of 8 x 128ah batteries set up as 24v.

2 x 190w 24v Kyocera Solar Panels linked + to + and - to - via 'Y' connectors supplied by the company and thereafter via supplied solar cables to the MPPT reg.

The controller is a Victron 75/50 MPPT.

+ and - cable inputs from the panels and + and - outputs via supplied solar cable to a positive and a negative splitter bar. These bars then split the supply into two so that both battery banks are being fed from the controller. There is a fuse installed on each positive feed to each bank. These fuses have always been intact.

There is also a Rutland wind generator connected independently to the battery banks through its own regulator.

When the MPPT controller is connected no LED's are lit which seems a bit of a design flaw as it took me a fair while to realise that it wasn't actually doing anything.

The banks have to be extremely depleted - 23v before the blue 'bulk feed' led illuminates on the controller. At that point the panels voltage was measuring 30.1v.

I would have expected the panels to continue charging the banks then move onto a float charge, however the led goes off and the controller remains dormant when the voltage gets to 23.6 and the banks therefore remained at 35% state of charge according to my battery management system.

Unless i'm missing something, I was expecting the panels to keep the battery banks topped up at 100% state of charge at all times when sitting on the mooring and no loads being taken from them, however it seems that the controller only kicks in when the banks are extremely low and then switches off again despite the banks being far from charged up.

I'd be really grateful for any thoughts on the set up or suggestions as to the problem.

Thanks in advance

[sensij]

Try putting your solar panels in series, instead of parallel. Maybe the voltage on them is dropping too low? The only kyocera panels I'm seeing are 20 V, not 24.

[Wy_White_Wolf]

What's the VMP and VOC of your panels?

WWW

[paulcheung]

Assume the batteries are 12 volt 128 ah. the bank is 24 volt 512AH. that need 1200 to 1500 watts panels to keep the bank happy. You panels are grossly undersized. no matter how you spin it, you need more panels.

[themacleanfamily]

Thats really interesting regarding there not being enough panels. Unfortunately i'm maxed out on space and these were the biggest 24v panels watt wise that I could fit onto the boat. I'm assuming if I just had the panels feeding into only one of the banks - therefore 256ah that I would still be under or would that help? Also I take it the size of the MPPT Controller is irrelevant in this scenario?

[paulcheung]

Unless you have other charging source, even one bank 256AH at 24 volt is too large for the panels, you need at least 21.5 amps charging current for C/12 charge rate. The most current your 380 watts panel can give you is 16 amps and on a boat even worse.

[LETitROLL]

Starting to pull my hair out with this one. I'm now on my 2nd of these controllers and still it doesn't seem to be working as it should. I've been offered a MorningStar Sunsaver as a replacement , however before I go down that route i'd be grateful for any advice regarding possible issues with the set up/choice of controller which may be the culprit.
I should say that I am not experienced in this field although I did do a lot of research prior to installing the system on my boat.

Boats electrical system is 24v split across two battery banks. Each bank consists of 4 x 128ah batteries linked to give 24v - Therefore a total of 8 x 128ah batteries set up as 24v.

2 x 190w 24v Kyocera Solar Panels linked + to + and - to - via 'Y' connectors supplied by the company and thereafter via supplied solar cables to the MPPT reg.

The controller is a Victron 75/50 MPPT.

+ and - cable inputs from the panels and + and - outputs via supplied solar cable to a positive and a negative splitter bar. These bars then split the supply into two so that both battery banks are being fed from the controller. There is a fuse installed on each positive feed to each bank. These fuses have always been intact.

There is also a Rutland wind generator connected independently to the battery banks through its own regulator.

When the MPPT controller is connected no LED's are lit which seems a bit of a design flaw as it took me a fair while to realise that it wasn't actually doing anything.

The banks have to be extremely depleted - 23v before the blue 'bulk feed' led illuminates on the controller. At that point the panels voltage was measuring 30.1v.

I would have expected the panels to continue charging the banks then move onto a float charge, however the led goes off and the controller remains dormant when the voltage gets to 23.6 and the banks therefore remained at 35% state of charge according to my battery management system.

Unless i'm missing something, I was expecting the panels to keep the battery banks topped up at 100% state of charge at all times when sitting on the mooring and no loads being taken from them, however it seems that the controller only kicks in when the banks are extremely low and then switches off again despite the banks being far from charged up.

I'd be really grateful for any thoughts on the set up or suggestions as to the problem.

Thanks in advance

Your batts are probably 6v x 4 = 24v per bank, then the 2 banks in parallel, so 24v @ 256ah total, one bank would be 24v @ 128ah, you would have roughly enough panel for that. As others have said you do not have enough panel(s) to keep the entire battery bank properly charged, however it still seems like there is something else also going on. When you first hook up the controller you hook it to the batteries first only (without anything hooked to the solar input) correct? That procedure auto sets the voltage for the controller and should get the led(s) working properly, it should be charging all the time because of the panel/battery size ratio, the leds should be more active.

[LETitROLL]

Try putting your solar panels in series, instead of parallel. Maybe the voltage on them is dropping too low? The only kyocera panels I'm seeing are 20 V, not 24.

+1, you do need to double check the voltage of your panels, and they do need to be wired in series for best results as long as the VOC x 2 does not exceed 75V. The 2 panels wired in series and hooked to just one of your battery banks would almost certainly work fairly well in good sunny weather, but you need to double check the specs on your panel(s) first to make sure. The symptoms you are describing are exactly what would happen if your panel voltage was too low, the mppt controller can take excess voltage and convert it to current, but with low voltage it can only charge when the battery is very low (below solar input voltage level), you have them hooked in parallel which only doubles current and keeps voltage same as 1 panel, almost certainly too low for this situation. Mppt controllers can boost current, they do not boost voltage, so you are best running higher voltages into the controller then it can adjust as needed, just do not exceed 75v input max.

[inetdog]

Your batts are probably 6v x 4 = 24v per bank, then the 2 banks in parallel, so 24v @ 256ah total, one bank would be 24v @ 128ah, you would have roughly enough panel for that. As others have said you do not have enough panel(s) to keep the entire battery bank properly charged, however it still seems like there is something else also going on. When you first hook up the controller you hook it to the batteries first only (without anything hooked to the solar input) correct? That procedure auto sets the voltage for the controller and should get the led(s) working properly, it should be charging all the time because of the panel/battery size ratio, the leds should be more active.

If you run the two banks in parallel, the rule of thumb would suggest 2(for 24V) x 256 Watts = 512 Watts as a minimum panel power.
You only have 380 watts if using an MPPT CC, so that is on the small side.
If you only run one bank actually operational at one time then the panel power could deliver enough for a C/8 charge rate, but you would have to worry about keeping the second bank charged and you would be going into a deeper discharge than necessary every day.

[themacleanfamily]

To answer some of the questions posed so far -

The panels are Kyocera KD190GH-2YU which have a rated VMP of 23.6 and Voc of 29.5.

The panels which are 24v are wired in series to the MPPT controller.

Each of the two battery banks consist of 4 x 12v 128ah batteries which are wired in parallel to give 256ah at 24v on each bank.

From what i'm reading here I only have enough panel power to feed one of the banks. This would be fine as I could adapt the system to have the wind generator feed into bank 2 which is totally isolated when not in use and the solar panels feeding bank 1 which runs the bilge pumps and therefore even when isolated may have the odd load as the pumps cycle on and off very occasionally to pump out the bilge.

If i'm correct in my assumptions above do you think that the MPPT controller I have currently (Victron 75/15 MPPT) is suitable or now way too big?

[themacleanfamily]

Apologies slight correction - The Controller is a Victron 75/50 MPPT not 75/15 as in the previous post

[sensij]

2 x 190w 24v Kyocera Solar Panels linked + to + and - to - via 'Y' connectors supplied by the company and thereafter via supplied solar cables to the MPPT reg.

The banks have to be extremely depleted - 23v before the blue 'bulk feed' led illuminates on the controller. At that point the panels voltage was measuring 30.1v.

The panels are Kyocera KD190GH-2YU which have a rated VMP of 23.6 and Voc of 29.5.

The panels which are 24v are wired in series to the MPPT controller.

Setting aside the battery sizing for the moment, you have statements here that conflict.

Panels in series are wired + to -, with the + of one panel and the - of the other connecting to your charge controller. If you are using Y-connectors as you initially stated, those panels are wired in parallel. Also, the voltage of panels wired in series is added, while your actual voltage reading (30 V) is consistent with the Voc of panels wired in parallel.

The panel you listed is considered a 20 V panel. A 24 V panel would have a Voc of over 35 V. It is confusing, sort of the way a 1/2" schedule 40 pipe doesn't actually measure 1/2".

If what you initially wrote is accurate, your system is cutting out because the panel voltage is too low. Get rid of the Y-connectors, wire them in series... the combined Voc will be 59 V, safely under the 75 V max allowed by this charge controller. When wired to a 24 V battery, that CC will be compatible with up to 1400 W of panels as long as the voltage requirements are met, so it is not close to being maxed out at all.

[Wy_White_Wolf]

...
The panels are Kyocera KD190GH-2YU which have a rated VMP of 23.6 and Voc of 29.5. ...

They are not nominal 24V panels. They are grid tie panels. You need to wire them in series to charge your batteries.

A 24V panel will have a VMP of 35 to 36 volts and a VOC of over 40 volts.

WWW

[themacleanfamily]

Oh Dear i'm really showing myself up here!

I've obviously mixed up my series and parallels which is probably confusing matters and has thankfully been spotted and pointed out.

However despite my attempt at confusing things I'm pretty sure that I should be able to get this system working with a few tweaks -

Re wire both the panels in series through to the MPPT although i'm not sure how best to do that so a quick run down would be useful.

Only have the Mppt connected to one battery bank as even wiring them in series wont be enough to charge both the banks.

Keep the existing MPPT as changing to a smaller one eg the 75/15 would have no effect on performance.

Am I getting close?

Really grateful for all the expertise here.

[LETitROLL]

Each of the two battery banks consist of 4 x 12v 128ah batteries which are wired in parallel to give 256ah at 24v on each bank.

4 x 12v 128ah batteries which are wired in parallel will yield 512ah at 12v

24v 256ah would be possible but would take a series/parallel combo, then you have the 2 banks in parallel again? We need you to double check that and make sure you don't have your series/parallel mixed up again so that we can make sure we are providing the most accurate help possible.