kgobisa

Hi there. 
 
Retrofit 20 Evac tubes with a Geyserwise to the 200l geyser and change the element to a 2kw so you can run it off your inverter if needs be. Then get a Paloma 26 or Rinnai gas geyser and connect that in series after the solar geyser. Set the gas geyser to 45 degrees so that it will only heat the water to that temp. If the geyserwise shows that the water in the tank is above 45 then turn off the gas geyser. If below 45 then turn the gas geyser on to boost the temp to 45. You can also try 48 in winter. 
 
I ran that system in my previous home and used only 18kwh per month from the Grid and a 48kg gas tank lasted 13 months with 3 adults in the home.