Air-water heat pump current consumption and data

You will pay taxes on the fed-in energy. And forgo the feed-in tariff if you consume it yourself.

That's true, it amounts to about €200 on saved/earned €1700 in 12 months.

Anyone who wants can gladly include the manufacturing costs, whether they would have speculated with the money or did not plan for it in the house concept.

I agree on ecological grounds. But a comprehensive view would be useful.

I don’t see the factor 3. Where does that come from?

Most of this has already been mentioned, but briefly again: No free electricity flows into the storage. It is charged with electricity that costs about 10 cents. Additionally, you currently don’t receive the 7.5-cent subsidy for this electricity. Then add another 20% for losses (also electricity at the above-mentioned 17.5 cents). Then such a storage system itself needs electricity. About 500 kWh per year, just so that it doesn’t break down. This electricity usually costs 30 cents. Then there’s degradation and at least one replacement within 20 years (which is usually the period considered for photovoltaic systems), so you really have to stretch yourself to break even.

Another factor is this: It often prevents (because of its price) the photovoltaic system from actually becoming really large. Photovoltaics must be installed on absolutely every roof (maybe currently not on north-facing roofs with more than 30° inclination, but otherwise on absolutely every one!). The larger it is, the more economical and better it is for the survival of mankind. But if the marketing folks now take 10,000 of my good euros for the storage, then many don’t have enough left to cover their roofs fully.

On the other hand – I have to give credit to the storage system here – I can imagine that many people only get photovoltaic systems at all because they are now led to believe they can be "self-sufficient" through storage. As long as it serves as a door opener, I have nothing against it. But those who already understand what’s going on would be better off leaving it alone and covering everything they have with photovoltaics.

Here is an example from the day before yesterday:



From 11:00 I am above 70%. At lunchtime I put all the variable consumers I have: hot water, dishwasher, washing machine (see the green hill of the upper curve). It’s just not that much. I run 70% softly – everything over 70% plus self-consumption I have to throttle. The orange part at lunchtime is then the battery charging to at least partly mitigate this throttling. It doesn’t work perfectly either, because from 14:30-15:00 the battery is also full... now it is throttled :( Daily consumption 10.49 kWh, of which direct consumption (i.e. the value that could have been used without storage) 6.21. Grid consumption was 0.12 kWh. Without storage it would have been 10.49 - 6.21 = 4.28, and without storage I would have had to throttle about 5 kWh more at midday.

Of course, this is not generally valid. I am even rather critical of storage, as I find it pointless to store at the single-family house level (if at all, then larger storage e.g. at the next transformer station or similar), and these things are anything but environmentally friendly. In the end, however, I am currently satisfied.

The real decision, however, was... surprise... the funding: only the battery separated me from the "+" at KfW40 (= 6K€ funding), plus 2K€ state funding, and through the simultaneous purchase of the photovoltaic system you get the VAT refunded. The 10 kWh including battery inverter cost 6.5K€. That made the decision pretty easy.

Crazy how our government throws money around. Every nonsense is currently being funded.

Crazy how our government throws money around. Every crap is currently being subsidized.

Even though I benefited in this case, you are unfortunately right. For example, I also get the charging station de facto fully paid for even though I don’t have an electric car. It’s not about sensible initiatives at all, but about whitewashing political measures ("we have subsidized xyz kWh of renewable energy," "we have built xyz charging stations," or in the case of the KfW double subsidy for granny flats, "we have built xyz apartments"). With photovoltaics, it would make much more sense to abolish all the bureaucracy (business registration, VAT obligation, depreciation, network connection application, 70% hard/soft, smart meter, etc. etc.). That would, in my opinion, achieve more.

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Quite a lot of effort for the small peak! ;-)

So: With a south orientation, it is probably mathematically 3-5% of the total electricity amount that is not compensated at a strict 70%. Since very few have a pure south orientation (and if they do, they surely also have a north roof, so why not just put a few modules up there too?!), the problem (which only exists at all in April and June) often does not occur. So: All roofs full = no problem.

On the topic of 40+: In that case, of course, you can take the storage with you. Even if it rarely becomes truly economical. Photovoltaic systems earn money, storage costs money. Even the gifted ones.