14 hours ago, WeNotGood said:

But then again if you can heat the geyser with excess produced renewable electricity (if you produce excess energy) then it acts as as a "store" of energy and the hot water is pretty much free.

I checked out the heat loss on my 200L Kwikot geyser and despite adding a solar blanket I was horrified to see how much the temperature drops overnight. The geyser manufacturers offer plenty of options but really good insulation doesn't seem to be one of them.

57 minutes ago, Vassen said:

How many degrees does it drop? I find my kwikot 200l superline to be pretty decent. Drops about 2-3 degrees overnight. I’ve lagged every piece of exposed copper. 
 

 

Where are you located and when did you do the measurement?

We need to compare apples with apples..

 

11 hours ago, Vassen said:

I went away last weekend and covered the tubes so that it doesn’t overheat. In 4 days, it dropped from about 77 degree to around 60 degrees. 
 

So the solar system was still connected? Is this an evacuated tube system with thermosyphoning?? 

12 hours ago, Vassen said:

I went away last weekend and covered the tubes so that it doesn’t overheat. In 4 days, it dropped from about 77 degree to around 60 degrees. 

So this is the temperature of your second geyser??

I have a mains Geyserwise controller which also has a temperature probe that replaces the thermostat. The readings vary a lot especially when the element is on.

I asked Kwikot about this and this was their reply:

The water will behave in a thermal cycle when the element is on – as soon as it switches off the water stratifies into layers with the hottest on top. The thermostat will then switch on again until this process has evenly distributed the stratification.

If you feel the inlet pipe of a geyser that has been on temperature for some time you see that it is hot.

At least 80% of the water will be at the thermostat setpoint after say 6 hours.

 

23 hours ago, Vassen said:

I find my kwikot 200l superline to be pretty decent. Drops about 2-3 degrees overnight. I’ve lagged every piece of exposed copper. 

I also have a 200ltr evacuated tube thermo syphon geyser, It also drops about 4 degrees overnight, I also made sure I lagged every piece, I even lagged the over temperature valve on top of the geyser because I could feel the heat on the valve and saw it as a point where lot of heat could escape.

 

8 hours ago, Vassen said:

Output of geyser 1 feeds into a 150l kwikott geyser

I was thinking to do the same to feed my dual 600 geyser from the solar geyser but I couldn't find the safe working temperature for the dual 600 geyser on the kwikhot specification I’m worried the temperature from the solar geyser is to high for the dual 600 geyser as I’ve seen my solar reach the upper 80’s on a hot day, also the solar tank is made from stainless steel and I’m not sure what material is used inside the dual 600.

 

7 hours ago, Richard Mackay said:

The readings vary a lot especially when the element is on.

I had varying readings more than a year ago when I just installed my solar geyser, it turned out the small thermo-couple rod thats about 4mm diameter were not making good contact in the 12mm geyser port, had to make a few adjustments before it became stable and it’s been very good since.

This video gives a good explanation of why a two-element geyser is superior to the single-element ones almost universally used in SA. 

 

https://youtu.be/Bm7L-2J52GU