TaliaB

The inverter generators should be spot on no problem there no need to bond.

PV doesn't have to go to the 2nd inverter if it doesn't make sense, e.g. if you have less than 8 panels splitting them 4 / 4 may actually cause your production to be negatively impacted as the MPPTs will only wake up later in the day due to the low startup voltages. If you have more than 8 then it may make sense to split the string between the inverters
For the battery if you can get a busbar now - it will make additional batteries easy to connect - so battery(ies) > busbar > disconnector > inverter(s).
Make sure the inverters are on the same firmware version before connecting them up in parallel, mismatched firmware may cause issues in the parallel operation

This battery is advertised by https://infinitygroupcompanies.co.za/index.php/product/200ah-48v-rosen-lithium-battery-wall-mountable/?srsltid=AfmBOor5h8kS9N1x5FxnhZUdgFaNZd74pJwcbn7HWqiLjkOTzTa67Sni
Agreed very good price but there may be a catch if out of stock.
"PLEASE NOTE THAT THIS IS NOT A STOCK ITEM AND MAY BE IMPORTED IF THERE IS NO STOCK ON HAND. IMPORTS CAN TAKE UP TO 45 WORKING DAYS TO ARRIVE IN SOUTH AFRICA. PLEASE READ OUR TERMS AND CONDITIONS FOR DELIVERY DELAYS

In your case you will use Mptt 1 and Mppt 2 so no the inverter will use all pv input power from both Scc's and convert it to ac output. The 60 A charge limit is one of the factors that is limiting your pv generation. I agree with @GreenFields at least 120A as you have 20kwh(416ah) battery capacity charging at 0.3C = 416 x 0.3=125A that is totally a safe zone for your lifep04 battery pack. Each battery will receive ~31A charging current.

Hi @Dry_Reef You are putting panel strings of unequal length in parallel to each other. Don't do that, keep the parallel strings of the same length. Also, your terminology is a bit non-standard, so what you're doing is a bit unclear. In any case, rather do the following: ...

For MPPT1: - Use the old 12x330w panels in a configuration of 6s2p, that means create two strings, each of 6 panels in length, put those two strings in parallel to each other, and then feed that combined set of strings to the 1st PV input. Point all these panels in one direction on the roof, eg. all North or all East, etc.
For MPPT2: - Use the 8 new panels in a single series string, and connect all 8 panels in series into your 2nd PV input. Do NOT put any of these panels in parallel to each other. Point all these panels in one direction.

For PV1 you can expect an open circuit Voltage of 6x47.0Voc, which equals 286,2Voc, but while it is operating, you're more likely to see 6 x 37.5Vmp, which equals 225Vmp and then up to 2 x 8.89A current at full power, or up to around 17.5A current.
For PV2 (edit: previously read PV1; Typo.) you can expect an open circuit Voltage of 8x47.7V, which equals 381.6V , but while it is operating you'd see 8x39.44 Vmp, which equals 315.5V, and then up to 15.21A current.

This is your best configuration. I understand you're trying to chase an optimum Voltage, but the setup here will also work fine, all within normal range, and without clipping of any current, and without any over-Voltage.
It's okay to increase the charge rate of the battery bank. Check the battery spec sheet for the ideal recommendation, but instead of 60A you can typically set the inverter to charge 120A at least, and still be treating your batteries well, considering you've got 4x5kWh batteries.

I hope this makes sense. If there's any doubt, please double-check it with someone like @TaliaB

Yeah, a faint humming or buzzing sound from the inverter is pretty normal especially when it's under load during peak solar generation.
Inductor Noise – Inverters use high-frequency switching to convert DC to AC, and the coils inside can vibrate slightly, causing a hum.
The fan should be running at peak solar production so the humming should not be audible when the fans are running.

And Maximum PV Short-Circuit Current per MPPT of 25 A

Yeah, a faint humming or buzzing sound from the inverter is pretty normal especially when it's under load during peak solar generation.
Inductor Noise – Inverters use high-frequency switching to convert DC to AC, and the coils inside can vibrate slightly, causing a hum.
The fan should be running at peak solar production so the humming should not be audible when the fans are running.

SABC News - Breaking news, speci...
INFOGRAPHIC: Eskom struggles to keep up with peak demand...
The latest data from Eskom shows that the power utility struggled to keep up with demand.

Maybe all solar owners must switch off their systems for a couple of days and see what will happen? 🖕

@zsdeThe list is based on NRS 097-2-1:2017. Here is an extract that answer your question.
NRS 097-2-1:2017
Introduction
This section of NRS 097-2 aims to be technology neutral and focuses on the interface between the 
embedded generator and the utility, 

Change the 4kw or 3kw element to a 2kw element half hour job then no nead to try and control the power with a SSR or by any other means.

Welcome to the forum. In which country are you residing? Did you try and connect the problematic inverter on it's own? Do a hard reset discconect utility pv and battery and wait 10 minutes for caps to discharge. Pre charge before connecting battery then connect battery only and see if the inverter restarts. If not you have a hardware failure and suggest you have it repaired by a reputable technician.
Ps. Just for interest sake you have 24kw power in a residential setup if i understand correctly. Do you have large inductive loads? What is your incoming utility supply rated for?

Measure DC voltage and current at each inverter under load and compare. A significant drop at Inverter 1 suggests a bad connection or higher resistance on the DC cabling. This happens with low pv generation and no utility backup pointing to battery issue on inverter 1.

Yes, a sudden drop in SOH like that, especially with moderate use (70% discharge and only 145 cycles), could be a BMS calibration issue rather than actual cell degradation.Try a full charge, then a controlled deep discharge (down to ~10-20%), followed by a full recharge. This might trigger recalibration.

"There are about 4000 homes in my property"
@Bobster. How big is you property?😁

Eskom compliance test report.
Compliance-Certificated-report-from-Customer-REV-8-14102021.pdf

Some insight between grid frequency and grid voltage:
A.Frequency Control (System-Wide)
Target: 50 Hz ± 0.2 Hz (normally).
Method: Eskom balances power generation with demand in real time.
How It Works:
If frequency drops (e.g., 49.5 Hz) → There’s more demand than supply → Eskom increases generation (or sheds load).
If frequency rises (e.g., 50.5 Hz) → There’s more supply than demand → Eskom reduces generation.
Control Mechanisms:
1. Primary Frequency Response (Seconds)
Power stations automatically adjust their output when frequency changes.
Example: If frequency drops, generators increase power to stabilize it.
2. Secondary Control (Minutes)
Eskom’s National Control Centre adjusts generator outputs to bring frequency back to 50 Hz.
3. Load Shedding (Last Resort)
If demand still exceeds supply, Eskom cuts power to some areas (load shedding) to prevent system collapse.
B. Voltage Control (Local & Regional)
Target: ±10% of nominal voltage (e.g., 230V ± 23V).
Method: Voltage is managed using transformers, capacitor banks, and reactive power control.
How It Works:
If voltage drops (due to high demand or long transmission lines):
Eskom boosts voltage using transformer tap changers or reactive power compensation.
Large customers may be asked to reduce reactive power (e.g., by improving power factor).
If voltage rises (due to low demand or excess generation):
Eskom lowers voltage using transformer tap changers.
Reactive power compensation (like capacitor banks) may be adjusted.

So 49.5 to 50.5 - which is what the various graphs presented here are showing. They just look scary because the Y axis is actually in small increments.

What type of generator are you using make and model. Program 03 on inverter settings ensure APL is selected and not UPS it gives you a wider input voltage range. As @ARC Lighting suggested your frequency needs to be as close as possible to 50hz. Do you have a DMM than can measure frequency then adjust the covenor to be close to 50hz possible with load connected to the generator. You need to try and get a happy meduim between load and no load.
Thanks for the input @frivan but try to refrain from the sarcastic last sentence remark above. In a different post(amplifier problem) you also remarked about electricians that uses testers and insulation tape and are not really qualified to test THD bit disrespectful to the profession unless i am just a tad sensitive

I'm taking the amp back to repair shop today. Want to see with my own eyes if it powers up normally.
If it does, I have mny questions they need to answer, i.e. whar components did they replace the first time round and why.

Thanks @Moffat
What power source is still available for off-grid application as fall back option - 1.Generators 2.Wind power generation.
1.Generator Considerations:
A. Fuel Costs: Running a generator to power a heat pump or electric geyser is expensive. A typical 5kW generator burns 1–1.5L of fuel per hour, which adds up quickly.(depending on generator size and load)

B. Inefficiency: Generators are best for short, high-load events (e.g., power loss due to inverter breakdown or running out of gas) but not for continuous heating.

C. Noise & Maintenance: Running a generator frequently increases wear, needs regular servicing, and can be disruptive.
If a generator is absolutely necessary, it should be small and used only to charge batteries.
2.Is Wind Power a Good Fit?
A.The site has consistent wind speeds of 4.5 m/s (16 km/h) or higher.
B.There are few obstacles (trees, buildings) blocking the wind.
C.You have space for a 10m+ high mast (higher is better).
D. Budget and maintenance cost is high.
E. Potential for lightning strikes and damage.(high masts)
 

20 x 5 mm copper busbar can carry 274 amps at 30°C
https://www.em.co.za/BRF1015?srsltid=AfmBOorYF8xiMaO9B35Xk7XuWaNeW7x_6J1zWADiboIbEFKK1CE10Ure

So then they can't be wired in parallel as the 100ah is 15 cells and the 200ah is 16 cells.

Use more than one start and stop time time during the same day. Your start time is later than your stop time as it spans across 2 different days.
Start it say at 00h01 to 06h00 for timer 1 and then add a 2nd start at 18h00 to 23h59 and see if it makes a difference. The idea is to start at the start of the same day.