Photovoltaics for hot water

So again:

What kind of water is in the buffer tank? Heating water or drinking water? Or are there two buffer tanks?

For example, we have one buffer tank for the heating system and a separate hot water tank for drinking water.

If we had a water-bearing fireplace now, it would only heat the heating water.

Please sketch the course of all components and pipes.

By the way, he was also surprised that the oven shows 0.0 for hot water.

Someone must have created that thing after all, so it should be easy to ask that person about it.

But it still seems nonsensical to me to heat huge amounts of water to high temperatures all year round when it can only be produced in huge quantities at very favorable conditions in certain cases, and otherwise the production of unnecessary amounts of water would have to be done using electricity.

I would invest the savings from the fireplace for heating water (i.e. piping, buffer tank, the extra cost from a normal fireplace to the required one, etc.) into a central controlled residential ventilation system with heat recovery.

Then, due to the low additional investment, you can probably operate a controlled residential ventilation system economically perfectly (Grym would go crazy with happiness) and would not have to cite only the luxury of not having to ventilate manually (and all the other conveniences) as an advantage of the controlled residential ventilation system... ;)

Besides, according to your statement above, there is even a favorable KfW loan including a repayment subsidy...

We have a 4 KW photovoltaic system and an approximately 4 KW hot water system on our roof. I wish I had installed 8 KW photovoltaic instead of this stupid hot water system back then. The photovoltaic system generates electricity every day (even in winter) and thus real money (feed-in + self-consumption). The hot water thing only produces hot water when the sun is shining strongly, which is 98% in midsummer, when you don’t really need hot water.. or at most 100 liters for showering. In autumn and winter, it supports the heating somewhat, but ridiculously little. Our hot water system cost about 4000 euros extra.. and if I save 50 euros a year in energy with it, that will be a lot. That means it will take a very long time to pay off.. and it will probably break down twice before that anyway. So my opinion... stay away from hot water on the roof.