We have good experience with the ST in the family and therefore want it as well. Even with relatively little light, you always get enough warm water; especially in winter, when the photovoltaic system simply does not generate enough electricity to cover the water heating and electricity consumption. With a sufficiently large water storage tank, it is practically like an energy storage. For us, it is especially important to be as self-sufficient as possible, not so much when the investment pays off. In summer, we will pass on our excess electricity to my mother before feeding it into the grid (you don’t get anything for it anyway).
You can currently forget about storage. Too expensive for too little storage capacity. I will always remember the presentation at a trade fair where the speaker had 3 or 4 logs lying next to him and said: would you pay a few thousand euros for that? That is roughly the energy yield of a 10KW storage battery... Everyone could really imagine how long and well you can heat with electricity from the storage. And electricity cannot be stored forever; I can’t charge my battery in summer to use it at Christmas.
We will not get an air-to-water heat pump but geothermal energy. Again, a proprietary development of our home builder that convinced us: the coils are laid under the floor slab; in summer, when you have excess electricity, the surplus energy (or at least part of it) is fed back into the ground, which can then warm up again and acts as a long-term storage. This prevents the cooling of the ground. At first, we were not so convinced about geothermal energy because we have the experience of an acquaintance who has geothermal loops in the garden. That means I am not allowed to plant anything deep-rooted and after 8 years, you can very clearly notice in spring that his garden still has snow longer than the neighboring gardens. The soil is therefore significantly cooled down. But with the soil activation through summer, that problem should be obsolete. And the basement will be quasi always heated slightly for free.
