Construction costs are currently skyrocketing

Unfortunately no, there are tax court rulings on exactly this issue and a very instructive video by a tax advisor precisely on this topic. Photovoltaics and storage must be strictly separated and in fact seen as individual assets. Photovoltaics are entrepreneurial, storage is non-entrepreneurial, unless I sell at least 10% of the storage electricity. The video is by the tax advisor Mücke: “no input tax deduction for battery storage.” And a tax advisor is usually quite creative... but not as creative as the solar technicians.

This is simply nonsense. It’s unfortunate to blindly trust a YouTube video in which the cited ruling is not even quoted exactly. If you had read the ruling yourself, you would have quickly realized that it is sensationally misrepresented. Because in the disputed case there was no joint acquisition of photovoltaics and storage at all. Two separate purchase contracts were concluded with a 4-month interval. Only the plaintiffs argued that the reason for the separate acquisition was due to delivery difficulties of the manufacturer, but a joint acquisition had been PLANNED. Based on this planning, they wanted to achieve equal treatment. And the court - quite rightly - denied this.

Then please read the BFH NV of 7.2.2018. The BFH does not care at all here whether the storage was installed afterwards or at any other time. Because “the electricity storage, for the subsequent acquisition of which input tax deduction is claimed, is not one of the essential components for the operation of a photovoltaic system.” That is a fact. The decision would have been no different in the present case even if acquired simultaneously. And by the way, I do not find the video sensational either, even if the tenor will not please everyone. But to each their own… as far as I am concerned, I see it the way the BFH does, whether the storage is on the same invoice, installed simultaneously or later… but everyone is the architect of their own fortune. Oh, by the way, the FG BaWü sees it the same way: FG Baden-Württemberg judgment of 19.02.2020 - 12 K 418/18 (incidentally contrary (!) to the administrative opinion).

My goodness, you really don’t want to understand, do you?

Let’s try logic: The BFH decision is from 2018 and confirms its permanent case law existing since 2011. And the tax authorities have probably waived this income from VAT out of pure generosity for 11 years?

This is a non-admission decision on a case that does not involve a simultaneous acquisition. Therefore, it is completely irrelevant what the court decided in this case. It rejected in particular because the question whether a subsequently acquired storage can still be a single allocation object has no fundamental importance and a further development of the legal application is considered unnecessary.

And your judgment of the FG B-W also deals with... oh wonder... a case in which the storage was acquired at a different time under a new purchase contract from a completely different provider.

First read the texts before you blindly quote and make claims here! It also doesn’t help to quote any half-sentences taken out of context.

I refer only to RZ 48 of the judgment from BaWü. Just read everything! By the way, there were only 4 months between the installation of the photovoltaic system and the storage. The delay was not within the "sphere of control" of the customer…nevertheless, the tax court did not follow the presentation of the taxpayer. Furthermore, the decree from the OFD Karlsruhe and also the notes from Bavaria are overturned here. I do understand what I am reading…

The delay was not within the "power scope" of the customer

Yes, it was! He first bought the photovoltaic system and because the battery was not available, but he wanted to secure the subsidy, he bought the battery from somewhere else 4 months later.

Oh dear... then Randziffer 48 in the quote (that is sufficient, at least for me, on the topic): "The independent assessment of the electricity storage with regard to the input tax deduction takes place regardless of whether the battery storage system was acquired or put into operation simultaneously with or subsequently to the photovoltaic system. The Senate is unable to identify reasons that would justify differentiation based on the acquisition or commissioning date." According to this, it is therefore completely irrelevant when what was ordered and put into operation here. And also RZ 49 because it fits perfectly: "The disputed question between the parties as to whether there is an extended construction phase or a staggered delivery or commissioning can therefore be left open, as can the question of whether the plaintiff is responsible for the timing." In my opinion, it couldn’t be much clearer (unfortunately).