KB - Kabelo

@madness_za, update on this. I put 6x computer fans to help cool the inverter. The results are amazing. I get 20% more efficiency and the inverter is always within the 45-60Deg range

So if people are still struggling with this, this is what I have done.
 
Dont judge my awesome paint skills as per attached.
 
Keep in mind that I dont have an essential and non essential BD. Everything in my house runs through the inverter.
 
I bought the following:
2 x https://www.robofactory.co.za/smart-switches/167-63a-1p-smart-circuit-breaker-with-monitoring-ewelink.html
1 x https://e-glow.co.za/products/ats-toq5-63a-ac-2p-230vac-tomzn
 
On my Deye inverter, I changed the Work mode settings to "Zero export to load"
 
Ran live and neutral wires from the "grid port" on the bottom of the inverter through a smart switch into the Source B (City power) on the transfer switch
Ran live and neutral wires from the "load port" on the bottom of the inverter through a smart switch into the Source A (PV and inverter) on the transfer switch
On the bottom of the change over switch 9The load port), I wired Live and neutral to the geyser.
 
On the smart switch for Source A (the inverter), I set the timer to come on from 11:00am until 15:30pm. I will use the sun to warm up the geyser, so we will have hot water at night.
On the smart switch for Source B (City power), I set the time for the morning between 03:00 and 06:00. Here I will use Eskom to ensure the water stays warm.
 
Note: Even if the city power smart switch is on, the change over switch will automatically switch over to Source A as soon as the source A smart switch turns on. 
 
Hope this helps...

you're correct, I read and understood it wrong. 
 
based on what the others say about. 
Then for my use case:
Ensure that eskom powers the house between 02h00 and 05h00 am. there is now way that this can be achieved on Growat without manually changing the charge priority to SUB.
 
Parameter 50 as now i understand it. will turn of power to anything that is outside of that time set.

Hi @KB - Kabelo
I had a similar problem to yours, we kept on running out of hot water because of "excess" hot water usage by the family (2 x teenagers and a wife will do that) 🙂 
I switched to a 200ltr solar geyser but we kept on running out of hot water. 
I still had my 200ltr standard geyser in the roof so I plumbed my solar geyser to feed into my standard 200ltr geyser. 
We have never run out of hot water since I did this as the water being fed into the regular 200ltr geyser is being preheated by the solar geyser. We essentially have 400ltr's of hot water now. 
The heat exchange solar geysers are a good option as the whole geyser is not pressurised which keeps the cost down and increases reliability. It is essentially a low pressure geyser with a copper coiled pipe going through it cold water gets fed in one end of the pipe and comes out the other side hot. The other advantage is that you do not get a lot of calcium build up in the geyser as the only water going into the geyser is to top it up occasionally. 
I purchased mine from Apollo solar and it was half the price of a regular high pressure solar geyser and has been working for the last 12 years without any issues. 
https://apollotechnology.co.za/copper-collier-system/


 
 

My neighbor has one of those, he is very happy with it, even with his extended family.

Hi @KB - Kabelo
What sort of heat loss are you getting from the geyser overnight? 
Geysers are regulated by SANS 151 (SANS – South African National Standards) and are usually pretty well insulated.
According to specifications  you should loose 8 to 10 degrees C over a 24 hour period (depending on ambient temperature)
If you are loosing significantly more than that you may be loosing heat from your geyser through the hot water pipes connected to the geyser overnight cooling your geyser down. A thermosyphon can be formed on the geyser here cold water from the pipes (heavier) is slowly circulated with hot water from the geyser (lighter) cooling the water in the geyser down. The effect can often be reduced by insulating the hot water pipes leading from the geyser. 
You can check if this is happening by feeling how hot the pipe is coming out of the geyser after an extended time of non-hot water use in the house to see how much heat you are loosing through the pipes. 
There is an interesting study on heat loss from geysers in South Africa that can be downloaded from https://www.savingenergy.org.za/wp-content/uploads/2019/05/Report_GeyserStudy_Final-Report-27-November-2014.pdf

Of course you can use a 300l geyser. Problem is when you use it in the evening it is replenished with cold water which reduces your overnight temp till morning a lot more than refilling it with already hot water.
As said, your elements should be timed to run sequentially, i.e. as soon as Geyser 1 is at max temp, only then does Geyser 2 element start.
Your own available solar power will determine if you can or can't do it.
Alternatively consider a gas geyser for the mornings fed from your 300L geyser that you have set your mind on

2 X 150l geysers in series would partially solve the problem. i.e. the hot water used in the evening will be replenished with hot water from the second geyser.
The two geysers can be heated during the day sequentially.
I have a 150l with 3kW element and even when my water is down to 30C it takes max 1:30 to get it to the max Geyserwise temp of 65C. So I could easily heat a second geyser to that temp too. All dependent on the size of the Inverter and panels obviously and of course the solar irradiance on the day. 
Today my geyser was at 31C and you can see the 3kW element starting at 08:58 and switching off at 10:20. So I could have heated another one from 10:20 to 11:50.