incagarcilaso

On the CCGX under Settings/Relay you can configure the relay. I'm not sure how the generator start and pump functions work, I assume the relay is then controlled by another subsystem, but the other two settings make more sense. The default is to activate the relay when there is an alarm condition, but you can also activate it manually.
If you set it to manual, you can control it in software using dbus, see attached images.
Doesn't look like an SoC based setting is possible out of the box, but it would be easy enough to make your own, at least if you have some python experience. You can look at my bms-bridge code to get an idea how to query and write a setting. That project has everything to create your own little service on the device. The constant querying of the value is a little inefficient, it is possible to subscribe to changes, but it's probably good enough.

The simplest option is to pass 230V through the BMV relay and push that into the SIG2 connector. I would assume that whatever is inside the heat pump will be a 230V relay or contactor drawing less than 1 Ampere, so that should be all you need to do. You would of course have to test it first and make sure it really uses less than 1 amp.
Second option would be to use a lower DC voltage, get a contactor or relay of the same voltage, and wire the contactor/relay to the BMV in the same manner. Then use that secondary relay/contactor to switch 230V into the SIG2 connector.
What I'd probably do is use a 24V signal. Standard irrigation stuff, and 24V relays are easy to find. Small 24V transformer, switching through the BMV, then run that 24V wire all the way to the heat pump. Place the 24V relay at the heat pump, and connect 230V via that relay to SIG2. This way you have a low voltage signal going to the heat pump and no high voltage AC on the back of your BMV.
Edit: The 24V scenario is how I switch my well-pump. In this scenario I use a RainBird irrigation computer that already HAS a 24VAC output for "master valve", I pass that through a rectifier (half-wave was good enough) and switch a small 24V relay (broken garage door openers and daylight switches are good sources for such 24V relays) which in turn powers the pump. This means I need only a thin 24V signal wire running to the pump, so I avoid a whole lot of compliance and safety issues that way.

Yes, and the last 3 weeks have shown them to be excellent. Here is an update for those who are looking at this technology: Within 3 days (yes, just 3 days on a bank of 24 1500Ah 2V cells!) the mid-point had been reduced from 4.6% (very poor condition) to be in the 0.2-0.4% in the last stages of bulk charge, although from measurements some of the cells were still clearly with a much higher and some with a much lower voltage than others (remember that because of the nominal voltage for operation of the HA02s I have to wire them up to pairs of cells not individual cells). This means that when there is a high load when the batteries are fully charged and that suddenly switches off, I still get the jump to a 2.6% deviation for a while. However, the HA02s continute to work and over the last 4 weeks they are now improving these voltage differences in the individual cells so that when this high load switch off occurs I'm not getting that jump in deviation as before. I've also noticed that they have changed the deviation on the strings so that sometimes the string that always had the lower voltage has the higher voltage - this is clearly when the boxes are passing more current to the lower voltage cells to equalize everything. Hoping that in the next few weeks all the voltage differences will be ironed out and I won't have any seriously damaged cells. The 4 cells with very low voltages are now perfectly balanced with voltages in the average range. They higher voltage cells are still slightly higher but nowhere near as much as before. I'm not expecting miracles so very happy to wait another few weeks for HA02s to complete their work with this very large, deep charge, battery bank. Just fabulous little black boxes!

Yes, and the last 3 weeks have shown them to be excellent. Here is an update for those who are looking at this technology: Within 3 days (yes, just 3 days on a bank of 24 1500Ah 2V cells!) the mid-point had been reduced from 4.6% (very poor condition) to be in the 0.2-0.4% in the last stages of bulk charge, although from measurements some of the cells were still clearly with a much higher and some with a much lower voltage than others (remember that because of the nominal voltage for operation of the HA02s I have to wire them up to pairs of cells not individual cells). This means that when there is a high load when the batteries are fully charged and that suddenly switches off, I still get the jump to a 2.6% deviation for a while. However, the HA02s continute to work and over the last 4 weeks they are now improving these voltage differences in the individual cells so that when this high load switch off occurs I'm not getting that jump in deviation as before. I've also noticed that they have changed the deviation on the strings so that sometimes the string that always had the lower voltage has the higher voltage - this is clearly when the boxes are passing more current to the lower voltage cells to equalize everything. Hoping that in the next few weeks all the voltage differences will be ironed out and I won't have any seriously damaged cells. The 4 cells with very low voltages are now perfectly balanced with voltages in the average range. They higher voltage cells are still slightly higher but nowhere near as much as before. I'm not expecting miracles so very happy to wait another few weeks for HA02s to complete their work with this very large, deep charge, battery bank. Just fabulous little black boxes!

Yes, and the last 3 weeks have shown them to be excellent. Here is an update for those who are looking at this technology: Within 3 days (yes, just 3 days on a bank of 24 1500Ah 2V cells!) the mid-point had been reduced from 4.6% (very poor condition) to be in the 0.2-0.4% in the last stages of bulk charge, although from measurements some of the cells were still clearly with a much higher and some with a much lower voltage than others (remember that because of the nominal voltage for operation of the HA02s I have to wire them up to pairs of cells not individual cells). This means that when there is a high load when the batteries are fully charged and that suddenly switches off, I still get the jump to a 2.6% deviation for a while. However, the HA02s continute to work and over the last 4 weeks they are now improving these voltage differences in the individual cells so that when this high load switch off occurs I'm not getting that jump in deviation as before. I've also noticed that they have changed the deviation on the strings so that sometimes the string that always had the lower voltage has the higher voltage - this is clearly when the boxes are passing more current to the lower voltage cells to equalize everything. Hoping that in the next few weeks all the voltage differences will be ironed out and I won't have any seriously damaged cells. The 4 cells with very low voltages are now perfectly balanced with voltages in the average range. They higher voltage cells are still slightly higher but nowhere near as much as before. I'm not expecting miracles so very happy to wait another few weeks for HA02s to complete their work with this very large, deep charge, battery bank. Just fabulous little black boxes!

Yes, and the last 3 weeks have shown them to be excellent. Here is an update for those who are looking at this technology: Within 3 days (yes, just 3 days on a bank of 24 1500Ah 2V cells!) the mid-point had been reduced from 4.6% (very poor condition) to be in the 0.2-0.4% in the last stages of bulk charge, although from measurements some of the cells were still clearly with a much higher and some with a much lower voltage than others (remember that because of the nominal voltage for operation of the HA02s I have to wire them up to pairs of cells not individual cells). This means that when there is a high load when the batteries are fully charged and that suddenly switches off, I still get the jump to a 2.6% deviation for a while. However, the HA02s continute to work and over the last 4 weeks they are now improving these voltage differences in the individual cells so that when this high load switch off occurs I'm not getting that jump in deviation as before. I've also noticed that they have changed the deviation on the strings so that sometimes the string that always had the lower voltage has the higher voltage - this is clearly when the boxes are passing more current to the lower voltage cells to equalize everything. Hoping that in the next few weeks all the voltage differences will be ironed out and I won't have any seriously damaged cells. The 4 cells with very low voltages are now perfectly balanced with voltages in the average range. They higher voltage cells are still slightly higher but nowhere near as much as before. I'm not expecting miracles so very happy to wait another few weeks for HA02s to complete their work with this very large, deep charge, battery bank. Just fabulous little black boxes!

It is, and these HA02s work wonders. The sooner they are fitted to any bank the better.

Don't worry about that - it helped clarify that all was OK. 
So, I am amazed! Yesterday, after just 3 days in operation (yes, just 3 days!), the marvellous little black boxes have brought my mid-point deviation down to 0.2% during bulk charge (which I have set at 55V at the moment while I am trying to get the batteries equalized). Even when these were first installed the best I saw was 0.4%.
So now, during the bulk charging phase, when the inverters hold the batteries at 55V for anything from 20 mins to 1 hour before settling them to float at 54V, I am getting a well balanced bank (although I still have to check the individual voltages in each of the 12 cells in the two strings). However, when in discharge and during charge up to around 97%, the mid-point deviation does increase to around 1% but I imagine that with time this will improve as well.
It seems appropriate that I bought these HA02s on aliexpress,com, the little brother of alibaba.com because they remind me of magic carpets, magic lamps and genies. They are like four little magic lamps that have flown in on a magic carpet and released the genies on my battery bank. I will never belittle inexpensive Chinese electronic boxes again!

Don't worry about that - it helped clarify that all was OK. 
So, I am amazed! Yesterday, after just 3 days in operation (yes, just 3 days!), the marvellous little black boxes have brought my mid-point deviation down to 0.2% during bulk charge (which I have set at 55V at the moment while I am trying to get the batteries equalized). Even when these were first installed the best I saw was 0.4%.
So now, during the bulk charging phase, when the inverters hold the batteries at 55V for anything from 20 mins to 1 hour before settling them to float at 54V, I am getting a well balanced bank (although I still have to check the individual voltages in each of the 12 cells in the two strings). However, when in discharge and during charge up to around 97%, the mid-point deviation does increase to around 1% but I imagine that with time this will improve as well.
It seems appropriate that I bought these HA02s on aliexpress,com, the little brother of alibaba.com because they remind me of magic carpets, magic lamps and genies. They are like four little magic lamps that have flown in on a magic carpet and released the genies on my battery bank. I will never belittle inexpensive Chinese electronic boxes again!

Benjamin Franklin in 1747 said current flow was from positive to negative. It was an arbitrary. He assigned two type of charge as positive and negative. No one at the time knew anything of electrons. JJ Thompson discovered electrons  in 1897 and we now know that they have a negative charge and if we apply a voltage electrons flow towards positive in a wire. But its not too difficult to remember that Franklin's convention is the flow of positive charge. If we dissolve table salt in water and apply a voltage the sodium ions (positive charge) flow from positive to negative. So if you think like a chemist and not like an electrical engineer everything is fine. 

 
Forgive my crude graffiti on your beautiful diagram.
Current flow is always circular back to source. To ease our understanding of what is happening we are going to divide this into two discrete units (it is not but will help our understanding).
We have a battery (source) which is high "powering" the HA02. The battery comprises two cells so current flow is into the HA02. Work is being done powering the circuitry and there is current flow back to source. So in effect there is a very small discharge. In the second half the HA02 is the source. Where the did it get is power from? The first set of batteries of course. We now are charging the low voltage pair and work is being done changing lead sulphate into lead and lead dioxide at the cathode and anode respectively. This chemical process raises the voltage marginally. Current flow is circular back to source which is the HA02 in this instance (not really but you get the picture). So yes it looks correct.
 

At around 220ah they are at 90% SOC - yes I'm lucky. I bought these second hand. They were 12 months old and came from a telecoms installation where they were in float for most of the time (emergency back up, which rarely kicked in). They have to change them every 12 months. They came with history, provenance and a 2-year guarantee but cost just 30% of the new price - otherwise I would never have been able to justify the cost.

Just so you can see what we are talking about - here they are, with the 4 HA02s connected. Gives you an idea of how difficult it is to shift these things around at over 100kg a piece and the way they are tied in together (two copper plate sheet connections on each). It's impossible to keep the balancer wires any tidier because of the way they have to reach each cell in each cluster.

Yes, I get the cricket analogy. Noted @Don, so if it becomes absolutely necessary I may be able to get some used cells to replace faulty ones from the same source as these, since they have to replace theirs every 12 months for brand new ones.

Yes, to replace them with new cells is a problem. I think a person should take the "Cricket" approach, lol. Granted, this will be very difficult to do as second hand batteries with a history is not something that is readily available. Are you familiar with cricket or have ever watched a cricket game? If someone hits a six and the ball goes over the pavilion and is lost, they bring out a box with balls that have done more or less the same amount of overs, that looks and feels the same as the ball that just got lost. They don't replace it with a new ball.  

That's nice and convenient.
Low voltage cells can be due to plates starting to short circuit OR they may in fact be in better health than the others and just take longer to reach voltage as there is still electrolyte available and the cell therefore has a lower resistance. 
Batteries that go high are definitely weaker than your other cells . Electrolyte is used up in the charging process resistance increases and the voltage goes up faster than the other cells.

At around 220ah they are at 90% SOC - yes I'm lucky. I bought these second hand. They were 12 months old and came from a telecoms installation where they were in float for most of the time (emergency back up, which rarely kicked in). They have to change them every 12 months. They came with history, provenance and a 2-year guarantee but cost just 30% of the new price - otherwise I would never have been able to justify the cost.

I have four balancers on the whole bank. Luck would have it that two balancers on these two very low voltage cells - just a fluke. I was measuring amps in the HA02 connection wires yesterday and I was surprised to see the values fairly low - around 1 or 1.5 amps in most cases. I was expecting higher readings. However, on the wiring conneceted to these very low voltage cells the readings were at 2.5A. This probably means that the HA02s are doing more with these particular cells, right? At any rate, I was expecting to see amps closer to the max values of 10A for the HA02s.

Dream: SOC of 90% is 150ah 

I see what you are saying but this is more about discharge percentages and full charge frequency than balancing. I agree with you that occasional deep discharges do no harm (although this depends on the battery technology type to some extent) and can even be beneficial in some cases.
The problem with batteries being out of balance (especially of the 2V type where you have 24 elements) is that some in fact never ever fully charge even though you think your bank has fully charged. When you talk about having a full charge at least once a week, you may see that the "bank" gets to 100% but if the individual cells are out of balance then what is actually happening is that some are over charging (all the time) and some never fully charge (stay at effectively 80%). When this happens they are not going to last very long.
In my case, I have 2 cells that are way out of balance from the rest and when the bank shows 100% charged and floating at 54V, these two are only charged at 2.07V (75%) rather than at 2.25V so they never fully charge and others are at 2.62V to compensate, which means they are way overcharged and floating far too high all day every day. This also means that as soon as the bank has to assume any load it falls straight down to 48.5V from 54V floating because of those poor cells and so they provide you with less power for less time. 
The bank readings only really give you a part of the story - the individual cell voltages will affect the life of the batteries as well as the amount of power they can give you each day when in discharge. I think balancing is crucial.

I see what you are saying but this is more about discharge percentages and full charge frequency than balancing. I agree with you that occasional deep discharges do no harm (although this depends on the battery technology type to some extent) and can even be beneficial in some cases.
The problem with batteries being out of balance (especially of the 2V type where you have 24 elements) is that some in fact never ever fully charge even though you think your bank has fully charged. When you talk about having a full charge at least once a week, you may see that the "bank" gets to 100% but if the individual cells are out of balance then what is actually happening is that some are over charging (all the time) and some never fully charge (stay at effectively 80%). When this happens they are not going to last very long.
In my case, I have 2 cells that are way out of balance from the rest and when the bank shows 100% charged and floating at 54V, these two are only charged at 2.07V (75%) rather than at 2.25V so they never fully charge and others are at 2.62V to compensate, which means they are way overcharged and floating far too high all day every day. This also means that as soon as the bank has to assume any load it falls straight down to 48.5V from 54V floating because of those poor cells and so they provide you with less power for less time. 
The bank readings only really give you a part of the story - the individual cell voltages will affect the life of the batteries as well as the amount of power they can give you each day when in discharge. I think balancing is crucial.

I see what you are saying but this is more about discharge percentages and full charge frequency than balancing. I agree with you that occasional deep discharges do no harm (although this depends on the battery technology type to some extent) and can even be beneficial in some cases.
The problem with batteries being out of balance (especially of the 2V type where you have 24 elements) is that some in fact never ever fully charge even though you think your bank has fully charged. When you talk about having a full charge at least once a week, you may see that the "bank" gets to 100% but if the individual cells are out of balance then what is actually happening is that some are over charging (all the time) and some never fully charge (stay at effectively 80%). When this happens they are not going to last very long.
In my case, I have 2 cells that are way out of balance from the rest and when the bank shows 100% charged and floating at 54V, these two are only charged at 2.07V (75%) rather than at 2.25V so they never fully charge and others are at 2.62V to compensate, which means they are way overcharged and floating far too high all day every day. This also means that as soon as the bank has to assume any load it falls straight down to 48.5V from 54V floating because of those poor cells and so they provide you with less power for less time. 
The bank readings only really give you a part of the story - the individual cell voltages will affect the life of the batteries as well as the amount of power they can give you each day when in discharge. I think balancing is crucial.

I see what you are saying but this is more about discharge percentages and full charge frequency than balancing. I agree with you that occasional deep discharges do no harm (although this depends on the battery technology type to some extent) and can even be beneficial in some cases.
The problem with batteries being out of balance (especially of the 2V type where you have 24 elements) is that some in fact never ever fully charge even though you think your bank has fully charged. When you talk about having a full charge at least once a week, you may see that the "bank" gets to 100% but if the individual cells are out of balance then what is actually happening is that some are over charging (all the time) and some never fully charge (stay at effectively 80%). When this happens they are not going to last very long.
In my case, I have 2 cells that are way out of balance from the rest and when the bank shows 100% charged and floating at 54V, these two are only charged at 2.07V (75%) rather than at 2.25V so they never fully charge and others are at 2.62V to compensate, which means they are way overcharged and floating far too high all day every day. This also means that as soon as the bank has to assume any load it falls straight down to 48.5V from 54V floating because of those poor cells and so they provide you with less power for less time. 
The bank readings only really give you a part of the story - the individual cell voltages will affect the life of the batteries as well as the amount of power they can give you each day when in discharge. I think balancing is crucial.

Hi @incagarcilaso
I use SolMon for my PVoutput uploads.  It uploads v7 to v12 which are the fields needed for the Extended Data.  The data is uploaded in the same string as the other pvo data and once each field is labelled in pvo then it displays as per my pvo extended data.
The mappings are as per my request to @Edmund Pohl during his development of SolMon.  I'm sure @Manie could add this in ICC.  The only change I would make is for the v12 which needs a small decimal shift
Be aware:  PVO is 5 minute data and so you WILL lose out on seeing spikes in the various bits of data.  So PVO is not a great monitoring tool for detailed analysis.

OK, so with thanks to @Chris Hobson for all his help via Skype the other day, I now think these are wired up correctly. Before making the changes the boxes were getting very hot - I now know why. Now they are not even warm. It seems obvious now that it was totally wrong to have the polarity reversed on some of the connections to the HA02 on some pairs. The complicating factor was that I was working in pairs of cells (because the minimum nominal working voltage for the HA02s is 3.6V), which gave me positives and negatives on both sides of each pair. Unfortunately, 6 days connected incorrectly means that the reverse has happened and the batteries are now even more out of balance - the low voltages are now lower and the high ones higher. On the positive side this would seem to suggest that these HA02s work and have an impact in a short period.
The first day of charging correctly today seems to show that they are doing what they should, although they may need some time to bring the imbalance under the 1% mark (currently running at 3.8% mid-point deviation). I have been measuring amp values in the HA02 connection wires today and the most I seem to see is 2.6 A in some while a lot are just around the 1A mark. This seems low but maybe with time this will change. In principal these could have up to 10A flowing through them.
@Mark's comment about jumping across the bank with the connection on single HA02s is interesting. I also wondered if this was a good idea. Now I am learning a little more about these HA02s I feel that it may not be an issue to have cells 1-4 and 21-24 hooked up to one box.
Another small disadvantage with these HA02s is they don't have any indicators on them at all - not even a single little LED to show when they wind into action out of passive mode. Let's see how it all progresses. One thing is clear - the bank now has to be better than just leaving it out of balance with the mid-point deviation growing steadily. That would have meant an early demise for the bank.

Lol, I know the feeling. 
Hang in there. It is a once off. You get it right, you never have to do it again.