I'm looking at installing a Geyserwise onto an old Kwikot geyser to give better temperature visiblity and control, as this is running from an Inverter with Solar panels and battery.

Do I need to drain the Geyser to install the new thermostate, or can this be done while the geyser is full of water (with power off of course)?

The Geyserwise Thermostat installation is a very simple . Replaces the existing unit, No water channel there. Buggest job ( not really is finding a suitable spot for the controller.

I did this for us not so long ago and works like a charm. I did a few extras on mine and willing to share if you like.

Awesome, was hoping it might be the case that it was in some sort of pocket.

Would love to hear what you added.

Currently the only thing that I'm considering doing (that would require draining though) is to replace the current 3kW element with a 2kW, because currently I often need to draw down batteries to run the geyser unless its absolute full sun at midday.

Currently have an ASC Wifi breaker on the geyser that can control on/off and measure consumption, and might leave that in place for consumption measurement anyway.

The Geyserwise Thermostat installation is a very simple . Replaces the existing unit, No water channel there. Buggest job ( not really is finding a suitable spot for the controller.

I did this for us not so long ago and works like a charm. I did a few extras on mine and willing to share if you like.

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The WIFI breaker is great. However do check the element again. Depending on area and geyser size .... My 150L Kwikot came with a 2 kw element.

I installed a separate contactor near the geyser to save the controller. Also the controller power is on inverter so is always on and will save the small backup battery.

But I see you are on the right track. 

Element definitely has a 3kW draw, but even with that could be an interesting experiment to see if pushing the temp a bit higher when running it on pure solar vs lower when just trying to get enough water for a shower early in the morning help with power efficiency.

Think ours is a 200l Geyser, but it's also more than 10 years old so tends towards bigger element.

Currently getting 75%-80% self-suffiency and if I can reduce power needed for it at the start of teh day that can be significantly improved.

 

 

I am also using Geyser Wise and heat the water up to 75c using solar during the day.

The water seems to still be hot enough for evening and morning shower.