No, not at all. Just if the battery lasts twice as long as your assumption, the price is (almost) halved. Only, that is not known today. At least the warranty periods of the manufacturers are now significantly longer than a few years ago. In some federal states, there are funding programs that reimburse almost half the price. With intelligent regulation, you can bypass the 70% limit and so on and so forth. At the core, I am not really a big fan of batteries, but these blanket statements are simply not correct. It is true that electricity from the battery is significantly more expensive than direct photovoltaic electricity, and you cannot get rich saving money this way anyway. If the parameters are not right, you quickly end up paying extra. But each case must be considered individually, and even for myself, I cannot say, because many factors lie in the future. If our battery ever breaks, then one could calculate, before that, it’s just guessing.