question

john-b avatar image
john-b asked

AC Thor 9S / 15000 Quattro - not frequency shifting

Morning all,

ive recently had a new system commissioned and I am struggling to get the Quattro to frequency shift for the AC Thor to kick in, we added the PV assistant in VE Configure and left the default settings, batteries are 100% and sun shining bright, I have 12.7kw of Solar panels with two 250/100 MPPTs.


Batteries are two sets of BYD 13.8.

Can anyone see what I’m doing wrong, AC Thor is set to frequency mode.

Assistants
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10 Answers
Lucian Popescu (Victron Energy Staff) avatar image
Lucian Popescu (Victron Energy Staff) answered ·

Hi John, please edit the settings of the Quattro, and in the charger menu, lower the voltage for absorption. The frequency is going up when the battery voltage is higher than the absorption voltage. Please tell me if that worked.

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john-b avatar image
john-b answered ·

Hi @Lucian Popescu (Victron Energy Staff)

please can you advise a recommended voltage to input, I am not too experienced with this system yet.


These are my setting for the two sets of BYD B-box 13.8s



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john-b avatar image
john-b answered ·

@Lucian Popescu (Victron Energy Staff)


these are my current settings


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Lucian Popescu (Victron Energy Staff) avatar image
Lucian Popescu (Victron Energy Staff) answered ·

So, you are charging the batteries using mppt chargers, correct? If yes, then the absorption voltage defined in the quattro must be lower than the voltage defined in the mppts. You can try with 54 volts, if it is not enough try to reduce it more.

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john-b avatar image john-b commented ·

Hi Lucian,


Yes the batteries are charged using the two 250/100 MPPTs, if I change the Quattro absorption to 54v then what should the Float setting be?

thanks


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Robert Bazalgette avatar image Robert Bazalgette commented ·
Hi Lucien,

Have you seen any improvements in the frequency shift control of the Victron ? I am still struggling with this. I am surprised you suggest playing around with the voltage settings in the charge controllers as a solution. Surely you can see that is a recipe for battery damage ? The settings for our batteries are very sepcific, and the system records voltages, so in the event of a warranty claim this would be a problem. Some of the other contributors here have described similar problems with the AC Thor and Vitctron inverters.

When the solar regulator starts to reduce charge current to the batteries because the target voltage has been reached, that is the time to start increasing the frequency. Whenever the charge regulator is on bulk, the frequency should be back to 50 Hz so the system doesn't drain the batteries.

Please can you feedback to software developers at Victron and ask for a proper solution.



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john-b avatar image
john-b answered ·

@Lucian Popescu (Victron Energy Staff)

I changed the absorption voltage in the Quattro to 54v and float to 53.8v and once reset with new parameters the AC Thor started taking power for about a minute then the frequency went back to 50hz and switched AC Thor back to standby.


still plenty of sun and only 300w ac output on the Quattro.

here is a picture of MPPT settings, can you see anything wrong in here?



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Lucian Popescu (Victron Energy Staff) avatar image
Lucian Popescu (Victron Energy Staff) answered ·

Can I have a look at that system? is it connected to vrm?

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john-b avatar image john-b commented ·

@Lucian Popescu (Victron Energy Staff) yes sure, how do I send you the details?

I can send portal ID or invite you?

64cfd94d04dc

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Lucian Popescu (Victron Energy Staff) avatar image Lucian Popescu (Victron Energy Staff) ♦♦ john-b commented ·

yes, can you please change my rights to admin?

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john-b avatar image john-b Lucian Popescu (Victron Energy Staff) ♦♦ commented ·
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Lucian Popescu (Victron Energy Staff) avatar image Lucian Popescu (Victron Energy Staff) ♦♦ john-b commented ·

Looks like it is working now, you can fine-tune it by changing that absorption voltage

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Lucian Popescu (Victron Energy Staff) avatar image Lucian Popescu (Victron Energy Staff) ♦♦ Lucian Popescu (Victron Energy Staff) ♦♦ commented ·

the frequency is high but the consumption is low, do you know the reason?

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john-b avatar image john-b Lucian Popescu (Victron Energy Staff) ♦♦ commented ·

Hi @Lucian Popescu (Victron Energy Staff), I presume it’s because the water is up to temperature, like now for example AC Thor is seeing 53hz but both heaters are already at temperature.


Thanks for your help, appreciate it

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Lucian Popescu (Victron Energy Staff) avatar image Lucian Popescu (Victron Energy Staff) ♦♦ john-b commented ·

With pleasure, you can delete my account from your system in VRM

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john-b avatar image john-b Lucian Popescu (Victron Energy Staff) ♦♦ commented ·

Hi @Lucian Popescu (Victron Energy Staff)

The frequency of the Quattro is still high (52.6hz) with no solar available so it’s now depleting the batteries ☹️

Do we need to adjust the parameters again?


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Lucian Popescu (Victron Energy Staff) avatar image Lucian Popescu (Victron Energy Staff) ♦♦ john-b commented ·

Hi, you need to play with that voltage and find the right value. It is pretty hard for me to do it remotely, especially having situations like the one above, when the water is too hot and the system is not consuming.

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john-b avatar image john-b Lucian Popescu (Victron Energy Staff) ♦♦ commented ·

Ok thanks, will make some adjustments later

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Lawrence avatar image
Lawrence answered ·

Be interested to know if you got this to work?

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Robert Bazalgette avatar image
Robert Bazalgette answered ·

Hi, Lucien Popescu, https://community.victronenergy.com/users/1959/lucian-popescu.html

I have a very similar setup to the one you have been helping here. It is slightly smaller. We have a 5 Kw Multi plus GX inverter, a 250 / 100 Blue smart MPPT charge controller. 5.2 Kw solar PV, and 48v 200 Ah LiFePo battery bank. We are using a MY PV Thor connected to a 3 Kw immersion heater for hot water.

We have the Frequency shift enabled using the PV inverter support assistant.

Sometimes this works quite well, but often in partial sunlight we see the batteries at 100% SOC, the Multi keeps the frequency at 50Hz, so the Thor does not deliver any power to the immersion, even when the water temperature is below 20 C. Power from the solar is reduced to a very small level because the batteries are full. When the boost function on the MY PV Thor is activated, power from the solar increases, showing there is surplus available. However this draws the full 3 Kw from the inverter, and draws from the batteries to make up the difference. It is not ideal, and means we are taking power from the batteries to heat water, which we don't want.

I am reluctant to mess about with the charge voltage settings, these are set in both the Multi and the MPPT controller to the battery manufacturer's specified values, and using different settings may invalidate warranty.

Please can you help with this ?

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Hi, unfortunately the only way to make it work is to play with the voltage on the multi side. Frequency will be increased only when the battery voltage is higher than the value defined inside multi for absorbtion.
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Robert Bazalgette avatar image Robert Bazalgette Lucian Popescu (Victron Energy Staff) ♦♦ commented ·
Hi Lucien,

You can see from this thread, and others, that the PV inverter support assistant does not work well for off grid water heating. I have a home built system using an Arduino, that works much better. I think Victron should sort out a better solution !

We monitor current in and out of the battery once the battery reaches absorbtion phase. If the charge current remains at the tail current level we know there is potentially more solar energy available, so we increase the power to the immersion heater. If that causes current to be taken from the battery, we reduce the power to the immersion. In a system with a BMS installed there is already a shunt resistor which shows the direction and volume of amps in or out of the battery, so all the assistant needs to do is query that once the batteries are at absorbtion level.

There are multiple devices available for on grid systems to divert surplus power to an immersion heater, but these don't work for an off grid, battery backed system. I have been struggling with this for over two years. To repeat :

1. The PV inverter assistant does NOT work well for off grid diversion to hot water.

2. It is really not a good idea to change the charge settings to accomodate the assistant. The assistant should work with the available data. Changing the absorbtion level on one charger and not the other ? Sounds like the battery manufacturer would not approve, and might invalidate warranty.

3. There are many off grid applications that would benefit from a means of diverting surplus solar to hot water. Either a dedicated separate control, for eg using the BMS shunt and a proportional relay. Or an assistant that actually works with the Multi plus, and changes the frequency so the AC Thor can operate properly.

Please can you raise this with whoever manages development at Victron. The ability to use the AC Thor and frequency shift control, would be a useful feature if it worked properly. Victron literature claims this is an approved configuration with third party hardware. My experience, and others, has not been good. We find two undesireable behaviours :

1. There is plenty of surplus sun but the Multi does not increase the frequency.

2. The frequency stays high beyond the period when there is surplus solar, and so drains the battery.

3. Having incorrect settings for absorbtion voltage has been cited as a contributing factor in premature battery failure, in one case.




1 Like 1 ·
Lawrence avatar image Lawrence Robert Bazalgette commented ·
Hi All,


Im an MY-PV Distributor in NZ and have done all the training on this system. Its not designed to divert DC coupled solar into an element on the AC side. It works perfectly diverting AC coupled solar from an inverter that responds to Frequency.

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Robert Bazalgette avatar image Robert Bazalgette Lawrence commented ·
The AC Thor works perfectly. It is the frequency respnse control of the Victron that doesn't. The assistant is designed as a way to limit the output of a PV inverter. What is needed is an assistant that is designed to increase frequency to control the immersion load. The immersion is on the AC side.
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Tallal Butt avatar image Tallal Butt Robert Bazalgette commented ·

As you are aware, In real stand-alone systems (without grid access) with Victron, my-PV power controller ("AC•THOR") reacts to changes in the frequency. You might be aware that this is controlled by the battery inverter according to the SOC of the battery. The regulation is therefore up to Victron and AC•THOR only react to it.

There are various setting on the AC•THOR to improve this. In every stand-alone system, however, this is definitely a trial-and-error process during commissioning, since every system is individual.

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Robert Bazalgette avatar image Robert Bazalgette Tallal Butt commented ·
Thanks Tallal,

I wonder if anything has been done recently to improve the situation with off grid diversion to hot water ? I found a firmware update for the Multi that seemed to have improved the response, but that has now reverted.

There is an issue with the SOC reported by the Multi. We have a BMS in the system that shows the SOC but it is not accurate at all. I believe this may be because the batteries are now a few years old. Even though they are holding charge, the SOC reading gradually drops from 100% when synchronised, to 0% after a few weeks. When the Victron MPPT shows float, and the batteries are at float voltage, but the SOC is reporting 0%. I could adjust the Ah setting in the BMS, but I don't know exactly what to set it to.

If the Multi relies on the SOC reading to control the frequency shift it makes it unreliable.

Do you have any suggestions ?

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nilsk avatar image
nilsk answered ·

Hi all,

I struggle with the same problem.

My config:

Victron MultiPlus 48/5000/70-100, Product ID 2624, Firmware v498, off grid

Victron SmartSolar Charger MPPT 250/100, Product ID A050, Firmware v1.61

Lithium battery YUASA 2x15 cells, 120 AH

REC 1Q-BMS on CAN Bus

Victron Venus GX

MyPV AcThor 3 kW single phase wiht a heating cartridge 2500 W, frequency control.

The MultiPlus frequency control setting is to go to 51 Hz at battery full.

ess.jpg

But it didn't work the way I hoped.

I want the frequency to increase in case of surplus.

This would be the moment when the Solar Charger decreases the charging power. But the frequency only increases when the maximum battery voltage is reached (my BMS is set to 60.02 volts). However, the control behaviour is such that the battery voltage drops to 59.79 volts in float and remains there. That's why the MultiPlus regulates the frequency down again immediately. So I only have a few minutes in which the AcThor could work. How can I ensure that the frequency remains at 51 Hz as long as I have a surplus?

071122.jpg

Thanks for your support!

Nils



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ess.jpg (31.6 KiB)
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Robert Bazalgette avatar image
Robert Bazalgette answered ·

Has Victron done anything to improve the frequency shift control ? It is frustrating to many users that this does not work well for off grid, where there is DC charging via MPPT solar charger. In a system where the Multiplus has VE direct communication to the charge controller it should be possible to make this seamless.

The frustration comes when the PV controller reduces power to the batteries, to maintain the charge profile. There may be kilowatts of solar power available, but the system only draws a few watts to keep the battery voltage in the target range. With the sun shining, and the HW cylindar cold, the system should respond by increasing frequency. The ACThor works perfectly when the frequency rises, dumping power to the immersion heater.

It is not adviseable to change the voltage settings in the battery charge algorythm. Surely a recipe for battery problems ?

I would like to see a separate assistant for frequency shift dedicated to HW diversion.


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