Pulse
It’s a shame you can’t do electric storage to use excess solar when you get it. This is my production and usage for last week with 250L tank from 1995 with a 9kw system. Element is 2.4kW on timer. I have installed a steibel eltron, found it very good, need 3 phase and issues running tap slow so hot water can cut in and out. Sometimes you need to open the hot water tap more to cool it down, paradoxically. I prefer storage types.
Which Steibel eltron model do you have? Do you know rough electricity consumption?
My current thinking to get around the minimum flow rate issues is to set their temperature output to the maximum comfortable temperature and primarily use hot water tap, only diluting a little bit with cold water if someone wants colder shower.
Which means I'd have to have different heaters for bathrooms and kitchen/laundry.