Pros and Cons of Ventilation and Exhaust Systems

Yes, it's not worth it, according to statistics there is about one failure here every 15 years.

Yes, the statistics. That will change in the future.

Our consumption is too low for that, and when it is heating season, it is too dark even during the day.

That's what battery storage is for. How high is your consumption?

For me, feeding in would be better.

Hmm... collecting about 10 cents for feeding in and paying about 20 cents for purchasing it.

You probably only miss the controlled residential ventilation once you have or had one. But I definitely wouldn’t get one just to have to ventilate less, because we don’t notice that in everyday life at all. Do you (non-controlled residential ventilation owners with more than 2 years after construction phase) regularly ventilate the house? We don’t - or not consciously. It’s more like we spontaneously throw open the windows because the cat farted or something.

Do you live in an airtight new building constructed in recent years?
In the apartment I lived in before, I didn’t have to ventilate either. But it probably had a higher passive air exchange rate than I do with controlled residential ventilation, although it was a very well-maintained building – it was just an older building standard that wasn’t as airtight.
You could especially notice that at the roller shutter boxes and beneath the window sills.

Yes, the statistics. It will change in the future.

I wish I had your crystal ball.

That’s what battery storage is for. How high is your consumption?
Hmm... collect about 10 cents for feeding in and pay about 20 cents for purchasing it.

At the moment, the cost per kWh of battery capacity is about 1500 euros at purchase (depending, it’s always open at the top). That means, for your cost example, you have to consume 15,000 kWh that you produced yourself so that 1 kWh of battery capacity pays off (10 cents per kWh difference). For a 5 kWh battery, you therefore have to consume 75,000 self-produced kWh yourself. Optimistically assuming 80% efficiency (even with the good, expensive storages the charging efficiency alone is 90%!), you have to produce and store 93,750 kWh with the solar system and consume the 75,000 when the sun is NOT shining (otherwise you can just use the solar power directly).
I am quite sure about the numbers for the break-even calculation that the storage is not worthwhile. By the way, the feed-in money you get immediately, whereas with the battery solution you are initially at a loss... if you are lucky and the maintenance costs are zero for 15 years and the battery withstands these 15,000 full cycles without losses...

No, I am waiting, at the moment prices are falling and when they are at one third then it might be worthwhile sometime.

Hmm... collect about 10 cents for feeding in and pay about 20 cents for purchasing in return.

The grid is a significantly cheaper storage than any battery.

At the moment, the kWh battery capacity costs about 1500 euros wholesale (depending on the source, of course, it's always open).

Proud prices. Only the market is cheaper.

The grid is a significantly cheaper storage than any battery.

The grid is not a storage.