Jankzilla

Don’t forget you need to know how much power those PoE switches are using. If you want to save some money, I would recommend buying a kill-a-watt for R400-R500 and conducting an energy audit. Figure out how much power you are actually using. For example, one of my computers has a 750W power supply, but it only uses about 250W most of the time. If I based my spec on 750W I would end up buying a battery 3x larger than I need, and the batteries tend to be the most expensive part of any such build.
 
Once you know how much concurrent power you need in watts, multiply that by the number of hours you need it for. So say it’s 1000W and you need it for 4.5hrs, that’s 4500Wh or watt hours (aka 4.5kWh). I would add a good 20-30% on top for safety and efficiency losses.

Also consider the difference between how much you’re actually using and how much you could theoretically use. Computers use way more power starting up or shutting down for instance. Your 1000W system might pull 2000-3000W at peak, so make sure to size the inverter accordingly.
I recently did the calculations for Stage 6 myself. It gets a little bit complicated if you are trying to work out the minimum requirement. If you are going off worst-case (ie a full 4.5hr outage instead of 4.1hr or whatever) and you need it to always stay on, you need to figure out the weird parts of the schedule. Particularly where one day ends and the next begins. For example, you will usually have at least 4.5hrs between outages, but every few days (where I live) we get a 4.5hr outage either 2.5hrs before or after a 2.5hr outage. So you have to figure that you either need to be able to recover for or from a 4.5hr outage within 2.5hrs.
 
One method is to get batteries that can charge that fast (honestly most rackmount batteries can do 0.5C which means that they can be charged in 2hrs with a sufficiently powerful charger/hybrid inverter) or to get enough headroom that whether you have 2.5hrs, 4.5hrs or whatever, you aren’t going to be so close to the line that you need to worry. The latter is the more expensive option clearly. Note that most rackmount batteries are 48V, I think the Pylontech UP2500 is a notable 24V exception.
 
Also note that some non-rackmount inverters frequently get placed on their back in a rackmount configuration but that isn’t really ideal as they are designed to be vertical for cooling purposes. If you are going to mount them in this configuration, make sure the room has adequate cooling.

You cant say no to my request and in the same sentence tell me you will provide best service.  I will still have to waste my time effort and money to make Dyness work.

This is far from truth, unfortunately you need to know your input from the grid side to determine your charge on the battery side if you are drawing from the grid. Same applies if you are drawing from PV. The inverter is not a generator and therefor you can not ignore the input power. 

That looks like a Growatt manual? OP has a Goodwe... (Perhaps you should read the OP 😛)

Are you referring to that PVmaster app? It is one of the most worse developed apps I have ever seen. 

My understanding is that legitimate Axperts (which could have a vastly different name, like a Kodak OGPlus) are made in the Voltronic factory, whereas clones are copies made in other factories in China, using stolen firmware and a schematic diagram reverse engineered from the real thing. The clone maker might understand the reason that an expensive part is used, and use a similar quality one, or they might just throw together any cheap junk and rely on the reliability reputation for the genuine Voltronics. They might use identical firmware, or reverse engineer it and make improvements. They might or might not avoid land mines (e.g. fault code 90) that Voltronic have put into their firmware to trip up the clone makers.
I don't believe that this is the case, although we know that some customisation does happen, e.g. the Inverex series. Someone posted recently that the same company that sells Inverex inverters also sells some non-customised Axperts under a different label. My guess is that Voltronics don't always have the time to customise every model. and/or the reseller doesn't always want to pay the extra for customisation, for smaller segments of the market.
At one point, it was clear that EASun was a clone maker; there is still a web page up by MPPSolar (one of the earliest and I think largest resellers of genuine Voltronics machines) that says so. But recent evidence strongly suggests that at least most EASuns are now genuine.
Some inverters, e.g. by Must Power, started off as poor quality clones, but seem to have evolved into their own models with different capabilities from the original Voltronics models that they copied from. I don't know what the recent build quality is like, but it seems vastly improved from what it was.
Companies like Growatt make models that are strikingly similar to some Voltronic models, but again, they seem to have evolved and improved.
All this makes it really hard for the poor consumer to know what to buy.

Here is probably the best resource on clones, posted by @Coulombon the Aus forum: https://forums.aeva.asn.au/viewtopic.php?p=71752#p71752

Never, EVER connect the neutral of two power sources to each other.  There is no country in the world where that is legal.
Neutral bonding means a relay that connects the neutral output of the inverter to the ground wire of your home.  The simplest way to do this is using a 220v coil SPDT relay.  The common connects to your ground and the Normally Closed (NC) connects to your neutral.  The relay coil is powered from your Utility power (ie. Eskom).  When the utility power cuts out the relay turns off and the normally closed and common terminal is connected.  Thus your ground and inverter neutral is "bonded".  When utility power comes back, the relay switches back on disconnecting them.
Note that this doesn't work perfectly because the inverter may switch at different times than the actual utility disconnecting.  So really the only way to do this in a complaint manner in pretty much every country in the world that requires it, is to have the relay switched by the inverter.  So when switching to inverter power, it powers a relay which bonds.
As to why this bond needs to be created:  Your home's ground wire is floating in respect to the inverter.  Meaning they are two different power sources and no way for current to flow between them.  Bonding creates a path.  There are different earthing systems.  South Africa implement many different kinds, there isn't just one kind in South Africa.  Some earthing systems have a stake driven into the ground at your installation.  Others have a ground wire coming from the utility. It is a complex subject.  Doesn't really change the fact that a bonding relay is required.  If you don't have a ground bond, your Earth Leakage doesn't work.  I mean apart from the fact that your installation becomes insanely dangerous
 

Here is my proposal. Charge batteries full and switch off inverter in DB until needed during LS. Switch inverter and DB on to charge batteries after LS event or once a week when no LS(wishful thinking) This will save 600Wh a day vs keeping it on and in ready mode.
Switch transfer to inverter when having LS. The whole DB is now running on E/Leakage and all loads connected to inverter. I see most people opt for the big frame size 63A transfer but I would use the cheaper 40A unit taking up 2 spaces.
Below is my circuit for the above. Self manage what big loads you can isolate on the DB.

Please ask if I missed out something.

Hi
I had similar requirements to you. I have 3 geysers. 3 fridges + bar fridge, pool pump with a heat pump and I used to spend around R5k - R6k per month on electricity. 
I went with 3ph Sunsynk inverter - If you want to save choose the Deye 12KW 3ph however repairs and support may not be so great if you need it. I went with one inverter due to less wiring and space required compared to 3 single phase inverters. It is cheaper than X3 Sunsynk 5kw inverters.  I was also considering Sunsynk 8kw inverter and changing all essentials to 1ph and keep non-essentials on phase 2 and 3 - This meant rewiring my DB board which I didn't anyone to do and I have a three phase aircon system which may not have worked properly had I done that.   
My base load without any heating appliances = 1kWh-1.2kWh. This includes - 3 fridges and 1 bar fridge, all lights, server rack (with dstv, pc, AV equipment). So to run the essentials for 2 - 6hrs I went with a 10kWh battery (X2 Greenrich 5kw batteries). A bit of risk since they are not proven yet but but it was the best value for money in terms of discharge rate, DOD and number of cycles. I was also happy with the performance warranty offered by the importer. The importer and supplier assured me that any issues will be fixed locally.   
Don't wait for Black Friday - rather get everything from your installer and make sure your installer offers good aftersales support. Any issues with the inverter and battery will be the installer's responsibility and not yours. If you are happy with dealing with suppliers and constantly following up with the importers with issues then go with the online stores.   
Seriously consider adding panels initially. This is where you really start to save money because the sun is charging your batteries and supplementing all your loads including non-essentials. My PV is mounted on a flat roof with water proofing. It is done with ballasts which don't puncture the waterproofing. Speak to many installers and get their opinion.   
 
 

Firstly, there isn't a lot of peer reviewed research for LiFePO₄, but the amount there is clearly shows that you will not get 16 years.  Age is significant factor in LiFePO₄ batteries (as with all battery chemistries but more so than it is for Lead Acid, in other words, Lead Acid can outlast, in terms of age, if you assume no cycles).
People like pointing out how things work on Solar Panels or Lead Acid.  However each battery chemistry is exactly that, an ongoing chemical reaction.  Solar Panels aren't chemical reactions (photons hitting a solid substrate to release electrons is nothing like a battery which is on-going reaction and has bazillions of electrons constantly migrating regardless of use).  Nor are two chemical reactions comparable just because from the outside it looks like a battery.  I think you may need a healthy dose of realism in that respect.
Secondly, for a LOT of battery manufacturers their warranty isn't worth the paper it is written on.  The company closes down or they simply claim abuse and you have no recourse.  So I wouldn't put much stock in the warranty either.  Google is your friend, the evidence is there.  Battery manufacturing is cut throat low margins and the people running these companies see their customers as their enemy (once the product is out the door).
In a LiFePO₄ chemistry, the electrolyte is a mixture that should "block" electrons from moving from the anode to the cathode.  There is undesirable electron migration from the anode to cathode which damages the cells by making it harder for lithium ions to migrate through the electrolyte over time.  Three factors determine the speed of this degradation
Battery temperature.  The higher your temperature, the faster your batteries will age.  This makes perfect sense as chemical reactions get more vigorous at higher temperatures.  But LiFePO₄ also shouldn't be charged below 0℃ so there is a balance, 25℃ is generally accepted balance. State of Charge/or cell voltage.  The higher this is the higher the electron migration probability is (Which is why Li-ion batteries last longer at lower states of charge).  Again this makes perfect sense because you have significant number of electrons at a very high energy state that want to move to a lower energy state.  And because of uncertainty principle, you will ALWAYS have electrons somehow making their way between the anode and cathode.  More charge, more probability.  We are talking on the scale of trillions of trillions of trillions btw. Discharging, each discharge does actually cause degradation also.  This is because a barrier forms between the anode and cathode that blocks lithium ion migration.  The more you discharge (not per cycle, just discharge in general), the more that barrier forms. Depth of drain is not such an important factor for LiFePO₄, in simple terms, the amount of Wh the battery can charge and discharge is finite (in total).  Wether you reach that amount by a large or small number of cycles you'll get similar results.  But because of aging it makes more sense to deeply discharge your LiFePO₄ battery to get the most out of it.  Obviously I'm not talking about beyond 90% DoD, then other factors come into play that will significantly reduce age.
Lastly because age is a significant factor in battery age (due to the electron migration problem), you should go for 90% DoD to get the most of out of your battery.  You aren't going to get 16 years, I can guarantee you that.  I would also be surprised if you get 10 years.  And in 10 years battery technology will have moved on significantly.  6 years is a realistic time frame for batteries up to 8 years I would say.
Small print: I'm not a chemist.  I love physics (especially quantum physics), electronics and find chemistry fascinating (but only have enough knowledge in that area to be a danger to myself if I were let loose in a lab).  So take anything I tell you or anyone else on the internet tells you with a grain of salt.  Research papers is the way to go and above is what I've gathered so far.  There isn't a lot of long life studies out there because LiFePO₄ has only existed since around 1996.  Especially don't trust manufacturers, they are trying to sell you something and their testing is not long term.  They make predictions based on short term testing which will be fully covered by their T&Cs saying that they believe their data is accurate.  But above is based on most of my reading and I believe it to be accurate.  If it isn't call me out on it, we can all learn more

Hi @Trish,
 
I’m not David but I can answer your question.
 
It’s hard to say how long a new battery would last compared to your old one when it was new. Gel batteries are supposed to be set up to only use half of the battery to keep the battery in good health for longer. This is called using 50% “depth of discharge” (DOD). But if the battery was not set up that way, you could get slightly less capacity from a similarly-sized lithium battery (specifically lithium iron phosphate, or “LiFePO4” as they are known) because LiFePO4 batteries are ideally used from 90% to 10% (in other words, you get 80% DOD).
 
Put another way: If the gel battery was set up correctly, you would get 60% extra juice with a new 12V 200Ah lithium battery than you got from the brand new gel battery. If it was set up incorrectly, you would get 20% less juice compared to when the gel battery was brand new.
 
As long as the lithium batteries you buy are capable of “parallel” function (being connected to other batteries in a way that increases capacity but not voltage, ie opposite of “series” connection), you can add more down the road. So you could get a 200Ah now and another 200Ah later if you wanted. Or you could get 100Ah and add more later. I think you can mix sizes but for simplicity sake I would advise against it, and never mix lithium and gel.
 
My advice would be to get a 200Ah 12V LiFePO4 “drop in” battery, or 2x 100Ah ones connected in parallel. That would probably solve the problem, and get you back to around where you were when the gel batteries were new. Plus they will last at least 8 years, probably 10+. “Drop in” batteries can be used with systems that do not normally support lithium, but you still need to check which charge settings to use on your inverter (eg you may need to change from “gel” to an “SLA” setting, check the manual for the battery). And remember you will need new cables/connectors if you go from one battery to two.
Good luck!
JC
 

More informed people will have to add their view, but common understanding is that you cannot just add newer lead-acid batteries to older batteries. Even if it were technically possible, I'd think that more lead-acid batteries would be throwing good money after bad. If the inverter allows it, I'd go lithium for the cycle life as a next step, but first goal would be to get maximum value for money out of the current batteries, cycle them for all they're worth while they're still good, and hope that a few months down the line the demand and supply situation has stabilised such that battery prices come down.
 

UPDATE
Dip switch on the slave battery was incorrectly set and the COMMS cable was incorrectly inserted. Instead of from MSTR battery out to Slave IN and MSTR in to inverter it was swapped around.
 
Batteries are performing optimally and inverter no longer trips from 2500 watt load. 
 
Thanks everyone!

In addition to checking the communication cable between the two batteries you also need to check if the dip switches on the batteries have been set up correclty for the master and the slave

Thanks very much @WannabeSolarSparkyand @Nexuss for the helpful advice.
My installer is a great guy and I'm sure he will sort it out now that we have a good idea what the issue is.
What a brilliant and helpful forum.
My first foray into solar was a couple months ago by burning out the MPPT controller in our camp trailer (panels in series just sounded so much cooler) and having to panic research and reinstall a new Victron unit the day before our camping trip.
Really enjoying the journey to a off grid system.

On your LiBMS screenshot the discharge amps is only 50A and that is your problem. It should say 100A. Looks like your batteries are not communicating with each other to tell the inverter that there is 2 batteries thus doubling your discharge capability. Check the comms cable between the batteries . When you get the LiBMS screeen to show 100A discharge limit its working correctly . Also change the discharge amps on you charging screen to 100A as 120A is too high. I also notice you dont have signal island mode ticked , make sure you have a neutral earth relay installed and then tick signal island mode. In your system mode settings you can untick the Use timer option as that will keep the batteries full ,kind of pointless to use the timer when you dont have solar...

Hi @Trish,
 
I’m not David but I can answer your question.
 
It’s hard to say how long a new battery would last compared to your old one when it was new. Gel batteries are supposed to be set up to only use half of the battery to keep the battery in good health for longer. This is called using 50% “depth of discharge” (DOD). But if the battery was not set up that way, you could get slightly less capacity from a similarly-sized lithium battery (specifically lithium iron phosphate, or “LiFePO4” as they are known) because LiFePO4 batteries are ideally used from 90% to 10% (in other words, you get 80% DOD).
 
Put another way: If the gel battery was set up correctly, you would get 60% extra juice with a new 12V 200Ah lithium battery than you got from the brand new gel battery. If it was set up incorrectly, you would get 20% less juice compared to when the gel battery was brand new.
 
As long as the lithium batteries you buy are capable of “parallel” function (being connected to other batteries in a way that increases capacity but not voltage, ie opposite of “series” connection), you can add more down the road. So you could get a 200Ah now and another 200Ah later if you wanted. Or you could get 100Ah and add more later. I think you can mix sizes but for simplicity sake I would advise against it, and never mix lithium and gel.
 
My advice would be to get a 200Ah 12V LiFePO4 “drop in” battery, or 2x 100Ah ones connected in parallel. That would probably solve the problem, and get you back to around where you were when the gel batteries were new. Plus they will last at least 8 years, probably 10+. “Drop in” batteries can be used with systems that do not normally support lithium, but you still need to check which charge settings to use on your inverter (eg you may need to change from “gel” to an “SLA” setting, check the manual for the battery). And remember you will need new cables/connectors if you go from one battery to two.
Good luck!
JC
 

Hi @Trish,
 
I’m not David but I can answer your question.
 
It’s hard to say how long a new battery would last compared to your old one when it was new. Gel batteries are supposed to be set up to only use half of the battery to keep the battery in good health for longer. This is called using 50% “depth of discharge” (DOD). But if the battery was not set up that way, you could get slightly less capacity from a similarly-sized lithium battery (specifically lithium iron phosphate, or “LiFePO4” as they are known) because LiFePO4 batteries are ideally used from 90% to 10% (in other words, you get 80% DOD).
 
Put another way: If the gel battery was set up correctly, you would get 60% extra juice with a new 12V 200Ah lithium battery than you got from the brand new gel battery. If it was set up incorrectly, you would get 20% less juice compared to when the gel battery was brand new.
 
As long as the lithium batteries you buy are capable of “parallel” function (being connected to other batteries in a way that increases capacity but not voltage, ie opposite of “series” connection), you can add more down the road. So you could get a 200Ah now and another 200Ah later if you wanted. Or you could get 100Ah and add more later. I think you can mix sizes but for simplicity sake I would advise against it, and never mix lithium and gel.
 
My advice would be to get a 200Ah 12V LiFePO4 “drop in” battery, or 2x 100Ah ones connected in parallel. That would probably solve the problem, and get you back to around where you were when the gel batteries were new. Plus they will last at least 8 years, probably 10+. “Drop in” batteries can be used with systems that do not normally support lithium, but you still need to check which charge settings to use on your inverter (eg you may need to change from “gel” to an “SLA” setting, check the manual for the battery). And remember you will need new cables/connectors if you go from one battery to two.
Good luck!
JC