Pudljumper

No new tech really. It's NMC batteries as far as I know. Mass production might bring down the cost though, that is what we hope. In addition, these cars now do significantly more than 200km on a charge, and rumour has it that some early models are showing 3000 cycles on their batteries already. That means many batteries will outlast the cars they are fitted to, which means a healthy second-hand battery market.
Also, they aren't the only people getting in on this. Bosch acquired Seeo a while ago. That's for NCA batteries, slightly lower energy density but still better than LFP, good enough for cars that is. Again, not really new tech, but hopefully cheaper as demand goes up.
Trouble with those is linear discharge behaviour, the voltage is proportional to the state of charge, and as soon as the voltage drops below the point where you can do reasonable work you cannot discharge any further. Also higher self-discharge I'm told. I think there will be a place for them, but I'm not sure they will replace battery banks soon.
We've been predicting that for at least 5 years now :-)
I've given up waiting on the new advanced tech that is supposedly coming. The tech that is coming is here already. It's Lithium Ion. It will just get cheaper.
If I am wrong, then at least we'll all be pleasantly surprised :-)

Aaah!  Johan what you have noticed is music to my ears. Solar installers work on 5 hours of good solar sun per day and yet in practice we do not nearly achieve that.
 
If you have a 25,5 kWh load shaped to your solar production. One of the disadvantages of lead acid is you have this long float necessary for the health of your batteries - not helping you daily production. @plonkster has recently purchased a lithium bank and is benefiting from the ability to operate it with the taps open so to speak. The is no need for a long taper charge (float).
 
 This is the reason why some European solar engineers are advocating East West facing panels. In the Northern hemisphere South facing panels give you the maximum solar production but the utility companies are paying so little for solar energy that it makes sense to generate power when there is at least someone at home.
If you plan to go off-grid then reduce you consumption by acquiring energy efficient appliances and light but also factor in 20-25% extra for growth. You don't want to be a solar Nazi for the rest of your life. "We can't have XYZ because we are on solar" does not cut it with the rest of the family. Obviously the heavy draw items are an issue but as the kids grow up they want fishtank/ game console etc - things that consume electricity.

I would steer clear of an Imeon purely based on the discussion on this forum and the experiences of senior installers. It would seem they suffer from Sudden death syndrome and the backup service (not sure whether this is peculiar to South Africa) leaves a lot to be desired. To my mind an Axpert would be a better bet. Not that I would install an Axpert either (watch TTT choke on his morning coffee). There are so many option currently. Depending on budget and requirements I would look at Victron, Infinisolar or  Goodwe or any of the mjainstream GTI charger/inverter combinations.
We have had this discussion before and I am in the same position. Spending that sort of tom I would go Lithium.
 
No Plonky I think you are close to correct. 

You size the inverter for the peak load (your batteries needs to be big enough as well, of course), there isn't a direct relation between the energy required and the peak rating of the inverter. It is perfectly possible to consume 10kwh a day using a 500VA inverter... if it runs at almost full capacity all the time (0.5kw*24 = 12kwh). In other words, yes, assuming you don't have loads over 3kw, the 3.6kva unit should be sufficient.
To store 10kwh (or thereabouts) in lead acid batteries, you'll need at least 4 x 200Ah 12V batteries (48*200 = 9.6kwh). But lead acid batteries don't like to be taken down to zero, you want to keep them above 50% most of the time, so you will need double that. Parallel strings (ie 2 strings of 4 batteries each) don't work as well as one larger string, so I'd advise you to look at 400Ah instead. Batteries that big don't come in 12V units, so now you're looking at 6V batteries or 2V cells. Best bang for buck here would be 8 x Trojan L16RE-B batteries (6V, 370Ah). That's going to set you back 50k just for the batteries.
I'd put 8 x 300Wp panels on that, probably Canadian Solar since they are fairly good quality and sell at a good price. You should be able to get that for around 20k. So you're at 70k, no inverter yet.
I would put a 3000VA Victron Multiplus on that, but I'm biased. It is a good inverter, in my opinion a better inverter than the Imeon, but the Imeon isn't a bad option... just don't use it close to the sea. It doesn't like moisture. Search on this forum for pictures of such an inverter that lived in a garage in Duynefontein. The Multi will cost you around 25k. Then you need MPPTs (because the Multi doesn't include one), that's around 9k for a nice big 150/70 (70 ampere model), so you're sort of at 100k, but you still have to buy cable and all the mounting materials. Thumbsuck, you might be able to do it for 130k, if you do most of the work yourself (but it comes with a much better inverter).
@Chris Hobson, am I being too optimistic?

Thanks Plonkster, gas stove and wind turbine are both on my shopping list. I'm a sucker for cool toys so here comes trouble!