Hi Bruce and welcome!

Have a similar setup to JDP - also 2x Axperts, 250AH battery bank and 9x 300W panels (2.7kW) roughly the same ballpark of R120K - but this was about 6 months ago and I went through 2x installers Not the guys here like Mike etc - they are all top notch. I did add some bypass switches and other gear though. I found that the electrical work can add quite a lot to the bill  - so depends if your current DB's etc are easy and "Ready"  - or if a lot of wiring/time is required.

My experience over the last 6 months have been great - I managed to cut the bill by approx 50% vs JDP's 90% -but I can explain why which is useful to know when starting down this road. It is but one part of your research though - there are many other factors around inverters etc - but the forum will answer that as you ask more questions.

The Axperts do not have the functionality to feed back to the grid - which is great for prepaid - and makes them cheaper (otherwise you would have needed some form of " limiter") - but the downside is that it cannot combine power from AC (Eskom) and DC (PV and/or batteries) to supply load. Easy example: Lets say your load is 2000W, and your PV generates 1800W at that moment - the Axpert will use the 200W from your batteries and everything is great. If however it's early morning and your batteries have now been discharged to the set % - say 60% - you need to charge them up first before you can use them again - takes a few hours. Same scenario - you need 2000W but the PV again generates 1800W - you will be switched to Eskom for the full 1800W load until the PV generates enough, or your batteries are fully charged to be able to combine PV+Battery. The result is often a few hours use from Eskom when you are only a little short on PV and any power generated more than what is set to charge batteries are wasted.

Now look at a smart inverter (the brands mentioned and a few more) - they can combine AC (Eskom) and DC (PV+Batteries) to supply total load. So in the above scenario only the 200W would be used from Eskom.

The only solution really with Axperts are to "oversize" your PV so that you have more than enough PV to carry load and charge batteries at max amps as per battery spec (shortest time) - It also allows for enough power when winter starts and the sun's position/clouds reduce your PV output substantially. So in principle an oversized pv array is a good idea - it does mean spending more $ of course and assumed you have enough roof space to mount 18+ panels. Your other option is to oversize the battery bank - but don't think anyone would advise that.

With regards to future proof - if battery tech/pricing comes down so that newer types of batteries become an option (Think Tesla etc - which are  better designed to be charged quicker - as well as cycle deeper) - you would need an inverter that is intelligent enough to connect to such battery banks' BMS (Battery Management System) - which unfortunately the Axperts are not able to do  - There are a few brands that are - some have been mentioned already.

Comes down to cost and what you are trying to achieve. - Spend as little as possible to save as much of your monthly bill or rather save some and be covered for load shedding. You do pay a premium for the expensive brands - they are better kit though, are more future proof and of course have some other nice to  haves like remote monitoring, etc.

Other things that also play a role is your spikes in current usage - which is needed to determine the size of your inverter - most "average" houses tend to spike to around 5000W - 6000W - and that's assuming your have energy efficient things like solar heating, heatpumps, gas, led lighting etc..If not then there are a few other items you need to look at replacing first.

Hope it helps!

 

21 minutes ago, Igubu said:

The Axperts do not have the functionality to feed back to the grid - which is great for prepaid - and makes them cheaper (otherwise you would have needed some form of " limiter") - but the downside is that it cannot combine power from AC (Eskom) and DC (PV and/or batteries) to supply load.

Just to clarify this - if you have an inverter capable of feeding back to the grid, the feedback option can be disabled as well in which case you will not have a problem with a pre-paid meter - you don't need a limiter to prevent feedback to the grid.

Adding onto Igubu's brilliant post.

Everything solar comes down needs vs wants ... and as I am now learning, be wise before you spend monies on inverters.

First reduce your load whilst splitting the solar load from the high draw loads like pool pumps, ovens / stoves if not on gas. 

Now you may need a smaller inverter.

Now do the sums of comparing the cost difference between adding more panels versus a R40k+ smart inverter that can draw from the grid.

I am getting a hint of a feeling stirring to from and idea to get a thought that maybe more panels could just be more cost effective over 20 years, especially if your 1500w geyser element can run off your inverter with all the needs loads (after you used the EV tube systems costs to buy more panels), that when Eskom charge per kWh is similar to battery costs per kWh, that you may just start winning the race with a lot of your needs load off-grid.

I have now been successfully running a 1500w 200l geyser for a month. It takes 5 hrs to heat the water. The thermostat is not accurate having set it to 70^oC it should take about 7 hrs. Working on the time that it takes to heat up I think our Delta T (change in temperature) is about 33^oC so my geyser is at 55-60^oC.   It works well. Solar geysers are much more efficient than PVs  but the advantage of PV panels is  you can choose to do something else with that extra power. I will post a fuller explanation on a similar thread elsewhere on this forum.

 

14 hours ago, superdiy said:

Just to clarify this - if you have an inverter capable of feeding back to the grid, the feedback option can be disabled as well in which case you will not have a problem with a pre-paid meter - you don't need a limiter to prevent feedback to the grid.

Thanks for clarifying - I didn't mention it in the post - and there are a number of other things around inverters, efficiency, etc that also play a role that I haven't mentioned

On 2/25/2016 at 10:53 AM, The Terrible Triplett said:

About 2 years ago a person at a government department said the way they catch people who are building without plans (new and extensions) is to compare aerial photos from few weeks/months back to latest ones taken. Working quite satisfactorily, she said, after having fined a number of owners that year.

A thought then passed through my mind, fleetingly, a split second burst ... I wonder when they will start to looking for solar panel installations, comparing it to approved installations?

We attended a course for installers by MAASA and present were delegates from COCT. They confirmed this is exactly what they do. They look at a google view of all the roofs in an area and compare it every few months. Whenever they see something on a roof, they will investigate and see if you are registered!