MetalFiber

What is quite fascinating to me is that though you'd expect the entire country to be perfectly in sync (at least anything where the AC is interconnected), it appears that it is possible for smaller parts of it to lead/lag for short time periods, essentially the kind of vector shift stuff that you also find with anti-islanding. I once read a paper about how such signals can be used to predict outages, I think the research/poc was done in India.

I worked at Tutuka Power Station for a short stint in the mid 80's. In the control room the station manager had two wall clocks with second hands, one driven from the 50Hz grid and the other by a separate accurate source. Part of the station managers responsibility was to co-ordinate (with other stations on the national grid) speeding and slowing of the grid so that the second hands of the two clocks remained in sync.

Thanks to all who have responded so far.
I've been running the system for the last few days, but I havent decided how I would like to implement it permanently into the DB.
Some feedback on what I have learnt so far.
I've never realised how many clouds are in the sky during the day until I started watching my PV output. Today was the best so far and I have generated around 23KWh. There is a bit of a difference between what PVoutput logs and what Emoncms logs, but I assume that to be due to the more frequent logging on Emoncms. I keep on comparing my output to @pilotfish as I think he is quite close to me, just to make sure he is also suffering from clouds and it isnt my setup acting up  I've joined the SA team on PVoutput as well.
Self consumption is good so far and I am able to use all PV power being generated.

You can see the reduction in electricity usage in the middle of the day. The high consumer in the morning was the geyser, due to a cloudy and cold day yesterday (and kids bathing the previous night), and oven in the evening.

I've got a trial of ICC running, which I find very useful, as I like seeing data being logged and being able to check up on my house remotely. I'm currently running it on a HP N40L microserver, but it seems to be getting overloaded with all the things I'm running on it, so considering getting a Lenovo Tiny PC to run these types of services on, and also my CCTV, or start trying to figure out the Pi version of ICC.
The inverter can indeed run on loads above 3KW. I've also tested it whilst running from PV in day time, and it is combining PV and Grid. The overload indicator lights up, but no alarm sounds. This makes me think I can connect more circuits to it once I let it feed into the DB, as it seems to handle load above 3KW at least for a few minutes, so I dont have to be too worried about the microwave or kettle.

There has been no issues with the prepaid meter yet. I assume it is because I dont have it in grid tie mode and not trying to push back into the grid, so that works really well at the moment.
I currently have the load side of the inverter going to a plug point, which I run my mining rigs off.
I need to consider getting my inverter setup more permanently. I'm looking at changeover switches and surge protection devices. If only one place could sell them all! I'm trying to keep my sub-DB circuit breakers and changeover the same brand (Hager), and possibly looking at their SPDs and PV fuse holder as well. Livecopper seems to be able sell most of these to me, but I havent confirmed all parts yet.
Once I've done that I'll also start thinking about the batteries. I'm trying to keep it cheap (backup power only, no real requirement for frequent cycling), but when you work it out the price difference between the cheaper option and the better quality isnt that big. Come on lithium, drop those prices, so I can rather spend my money only once.
I guess that is all for now.
Thanks for reading.
 

Hello Analytical,
 
I'm new to the Forum.  This is my first reply to anyone.  I, too, am fairly new, but I have gathered a lot of information on YouTube from many different people.  What I have found is interesting to say the least.  To answer whether your unit will handle beyond 3kw...well, that's not something I would try, however I did view a video on YouTube where a guy in Africa put 3 times the rated power of his inverter through it because he set it to Utility only.  That said, I'm not sure that's a good idea, but apparently it's been working for him.  If that's true then my test unit, a little 2400W hybrid inverter should be okay.
My unit, like yours, was probably made by MPP SOLAR.  And yes, there have been a lot of differing views on it.  Personally I think some guys are maxing the units beyond what they were made to do.  My test unit is exactly that, but I only test to the limits and not over.
 
For instance you mentioned more amps than watts...Though it is necessary to run higher amperage at times, I would try to avoid higher amperage.  I set my PV array with higher amps in mind, at first, to help charge the batteries faster.  I reconfigured it into serial to keep amperage down for two reasons, to keep the heat from the amps at lower temperatures and to keep from excess amperage when the "cloud effect" occurs.  Still, higher voltages can also incur problems in the system, but it's less likely to burn anything down due to heat.  Here is a video of two loads running.  I have a video with three, but it went into over voltage and switched to grid use once about 55 amps were reached.  
What I will say is MPP SOLAR (Axpert or Infini) should not be used beyond their specifications and one should really read the manual carefully.  There are some not so easy to understand points where maybe a translator (Chinese to English) did not work well.  A guy who's had experience for four years recently posted/asked how to set up [1] to either SOL, SBU or UTI.  Two guys on there thought SOL meant just using SOL was the most efficient way to run the machine.  I guess it depends on what efficiency means to each user, but if they mean the "least amount of utility used", that would mean to use SBU (Priority is Solar, then the Battery and finally Utility).  So yes, even older users can be fooled by the wording or translation.
Here is a video that goes through a little bit of the Menu setup adjusting the [1] and [16] selections.  I hope it helps you see some of what you'd expect from those units....though I think your Infini is a bit more advanced than this one.  
It may be a Hybrid, but I think that France's Imeon is a bit more robust...as they have a really top end warranty.  This is where MPP SOLAR and all it's clones have some "maturing" to do, but for the price...it's still hard to beat especially if you're just learning.  Much cheaper to blow one of these units up than an Imeon, an SMA, a Kaco, etc.  SolaX, Goodwe and Growatt are also Hybrid, but are Chinese.  That said these are top quality Chinese brands at higher prices.  What I am finding, though, is that MPP SOLAR is now also making units for Growatt, Giant and Voltronic.  All of them exactly like that of Axpert, Infini and others.  The regional certifications probably change a bit of their circuitry to pass in different countries, but the unit and its' operation are the same.
Your unit might have parallel capabilities.  This might solve issues of going over while still using a set amount of PV.  If you have three units, you can actually build a three phase system and just connect it to a junction box where you can separate them into three phase and single phase "areas".  Three Inverters in parallel with a 4000W PV array will still give you more, per day, than your 15kW a day use.  I believe the unit you're talking about has some grid tie capabilities.  Mine doesn't give back to the Utility company, but I can supplement my system with it.  But at 4000W worth of PV that gives you 4000x.8x5.5=17600W = 17.6kW a day.  (0.8 is average because there's inefficiency and 5.5 is an average total "perfect" sunlight ~ not knowing how much actual sun you have).  Anyway, I aimed slightly higher for your system though you only need 15kW a day.
I've written a lot too now.  I hope it helps and, at least, answered some questions.  In the end, I personally think the MPP SOLAR's and their clones are fine if you don't try to kill them.  If you want the best...then SMA...period, but once in a while they will also fail.  Still, there are two guys I know with SMA's and MPP SOLAR (Infini).  They love their MPP SOLAR and they know their SMA's will work.  I know Outback is coming out with their Hybrid and many others are following suit.  That says "something" about hybrid units that MPP SOLAR have made popular.  It's making a sweep of the market structure for sure.  I think they've solved a lot of issues through software.  My test unit is only three months old and before I started videos, I did a lot of tweaking.  The battery was the hardest part, but I later found out that people were draining my water tower so the battery kept coming on (at night) and drained the battery along with the water.  Hahahaha....that problem has been resolved.
 
Anyway good luck.  Hope it helped either way.
 
Peace..