Wingman

Hi Wingman
Option 2 works like this.
Maximum charging current = utility charging current (option 11) + solar charging current.
So setting option 2 to 20A and 11 to 2A should do the trick.

Option 16 should be on CSO for utility to be able to float the bank when on bypass mode

A link to AICC
http://aicc.org.za/

They sell Victron stuff yes, but also a lot of other stuff. There is also Ontrack literally just around the corner from ExSolar (at "The Interchange" in Somerset West). ExSolar has it on the shelf though. If it was me, I'd just order it from Sonopsolar and have it shipped to my door :-)

Your system is very similar to mine except that I went for 8 x 6 V 225AH Trojan T105 batteries and 2 x Inverters in parallel with the total house load connected to the inverter output. The MPPT operating range of the inverter is 60 to 115 VDC. So if the maximum voltage of your panels is 37 V under load, a set of three will give 111VDV, still below the specified maximum. However a set of 2 panels only produces 74 VDC and that is maximum. It would seem that 2 sets of 3 panels each may be a better bet. The bulk charge voltage of my T105's is 59.3 V but the maximum of the inverter is 58.4V so that is what I set it at. Switch back to grid is set to 44V but only to ensure that I don't discharge below somewhere around 50% in case of Eskom going belly up again.
The Inverter is controlled by AICC which I really like. It makes it easy to control the inverter from my computer. On AICC I set Switch to Solar at 100% and Switch to Grid at 80%. Hopefully I will get the maximum battery life with these settings. Also the inverter is set to charge the batteries only from solar (Setting 16 is set to OSO). Hope all this helps and does not confuse you even more. There are also some additional settings on the inverter that has to be set appropriately for AICC to work as expected.

Was just about to say that. Look at the cycle life chart. A 10% DoD won't shorten their life much more than just floating them all the time. So just cycle them 10% then and do self-consumption during the day :-)

Well I won't say that is the only way. There are other ways, makeshift ways. On my fancy Victron charge controller there is a nice stat I can access via the LCD that tells me how much time was spent on float today. When I come in in the afternoon, if that indicates that we spent at least 3 hours on float today, I know we're full.

Hi Wingman
Welcome. I hope I can give you your piece of mind I was busy typing when you asked for my help (again). Don't panic I am not the only one who knows these inverters well.
48V as a start. The problem with using voltage for switching is that load influences voltage. 48V is roughly 50% DOD. If you have heavy loads you may have to lower this as a heavy load lowers voltage more than a lower steady load. After the draw from a heavy load ceases battery voltage can actually recover. Bulk 58.8V as you have been advised (2.45 V per cell). Float 54.5V Determined from your datasheet (2.27 V per cell) Leave it at 42V otherwise you scramble the Axpert's calculations. Purchase a BMV 702 to protect your batteries. Max Charging current (Program 2) set to 20A. This if for solar and solar/ESKOM. MAX AC (Program 11) set to 20A. Determined by Program 2 so you do not have to set this separately.  
I think others have alluded to this but your batteries are not really suited to a solar application.
So what my recommendation is that you use solar during the day and work off grid at night, saving your batteries for when the power is off. This can be achieved by setting Program 1 to SOL and Program 16 CSO. This is a very poor way of controlling the inverter and perhaps a geyser timer on your inverter will help or getting software like Jaco's AICC or TTT and Ed's SolWeb.
If you are worried about cooking your batteries you can reduce the bulk charging rate to 58V in summer (>20oC) since the bulk charging rate is above gassing voltage.
Chat to @Camel about a BMV or ExSolar in S West is a Victron agency. @Mike an installer in Yzerfontein may have some tips and be prepared to give your system the once over. I will be in CT in Nov and if at that time you still not sure I can pop round.
 
 

@Wingman, that will make a difference, please keep us updated on the performance. I have learned this the hard way, the only way to know the condition of your batteries is by using a battery monitor. Most guys stick to the Victron BMV 700 or 702. The benefits in installing one  outweighs the price by far. It gives you valuable info about the Discharge/Charge of the banks, and the installation is very easy.  Please Consider buying one, it can really prevent you from damaging your battery bank.
 
EDIT: I got mine from a forum member @Camel, he had the best prices at that stage, and I think another member @The Terrible Triplett also sells them. To my knowledge, there is no shop that will beat their prices. (When I was in the market for one, no shop came close to their prices)

3 In series puts you at 135V open circuit and 111V during normal operation. The spec sheet of the inverter says max Voc is 145V, and the operating voltage between 60V and 115V. So it feels to me like both Voc and Vmp is a bit close to the upper ends, which might be why the installer went for just two in series, leaving you with a lower 74V and 90V. Probably makes no sense to change it now, just go with it and see how it turns out. It should work just fine.

WOW - Plonkster, I am so far out of my depth I have no idea what is going on and am 100% willing to do what you guys recommend I should do. I have almost no knowledge of electricity only mechanical ability to install the stuff on my roof.

PLEASE  HELP
I have Rectron 5KVA inverter
 8 X 100AH Lead Acid Batteries connected to produce 48Volts
6 X 310Watt Solar Panels connected 3 sets of 2 in parallel

 
Please Please Please will someone PLEASE tell me how to “setup” the Inverter. I please need to know the following cause I could do the installation using logic and common sense but I don’t have the knowledge or understanding to do the INVERTER set-up and fearful I may damage/cook/boil the batteries. I need to know:

 
·        Point Back Voltage (drop batteries and back to utility/Eskom) ·         Bulk Charging Voltage: ·         Floating Charge Voltage: ·         Low DC Cut-Off Voltage: ·         Max Charging Current: Solar ·         Max Charging Current: ESKOM/utility ·         Max Charging Current: Solar + ESKOM PLEASE will some of you electrical wizards come to my rescue and “save the day”? Thanking you in advance.

@Wingman According to this document your Bulk Charge should be set at 58.8Volts and your Float charge at 54Volts

As for your low voltage cutoff settings, you will soon learn that you can not rely on the Axperts voltage indication as a correct Dept of Discharge or State of Charge indication. To tell you to set it at for example 47 volts will be unfair. because depending on the load and the rate of discharge, 47 volts might mean that you are sitting at a 40% or 50% or even 70% dept of discharge. The recommendation will be to plan for a Battery Monitor and use that to determine the low cutoff point instead of the Inverters internal setting.
The change back to AC setting is also personal preference and I would allow a guy like Chris to rather give his opinion first. 
Hope that all of this is making sense, if not, please ask and I will try to simplify my answer.

Thanks Wingman,
So what is the open circuit voltage of those panels?
Questions that i can answer.
You've got a 200Ah bank. It is recommended that you charge your bank at between 10 and 13% of the total ah, so in your case that will be 20 to 26Amp. This inverter has settings for 10A. 20A and 30A. I would chose 20A to be safe. I think the AC charging setting is personal preference, depending on if you want to allow charging from grid. I would say that it would be safe to limit the total to 20Amps.
I will feel more comfortable answering the rest of your questions after i know what batteries youve got.
A guy called @Chris Hobsonknows these inverters quite well, I am sure he will join soon. His got a post on this forum somewhere with the Axpert settings, That document explains everything very well.
 

Welcom Wingman
Some of your questions can only be answered with some more info. Name of battery ?(The data sheet for the specific battery will answer your questions related to the battery) And can you give some more info on the inverter. Maybe a link to the Manuel. Most Mppt,s used on a 48volt bank will only start working at about 60volts, so your setup with 2 panels in series would have to change to 3 panel in series.