Is a photovoltaic system also sensible in the West or East?

Hopefully it won’t come back. Photovoltaics are marketable and no longer need subsidies.

I would be interested in the calculation for private roofs

If I calculate in my profitability analysis for my 24.5 kWp system with a 3-cent market price and a self-sufficiency rate of 35% without storage, then after 20 years I end up pretty much exactly at 0€. That would really be too risky for me, that it turns into a loss-making business.
Something is marketable if it makes money. I would say that a photovoltaic system on a private roof without feed-in tariff has not been marketable so far, so I wouldn’t call it marketable without the feed-in tariff either.

I very much hope that some form of subsidy will continue somehow, otherwise the photovoltaic market will collapse quite strongly, with all the consequences.

Bookstar spoke of a new subsidy that is necessary. It is not necessary at all, as hampshire wrote. On the contrary, the return (paid by the citizens through the Renewable Energy Act) is in my opinion even too high. It was 8.5% for me in 2019, before taxes and without taking energy consumption into account. You have to be crazy not to cover your own roof. I would like to have your 24 kWp

I would be interested in the calculation for private roofs

You just have to change your way of thinking. The "business model" changes.
The calculation is very simple. You produce your own electricity at 20+x ct (x = price increase energy purchase) cheaper than the purchase price. You size the system for self-consumption optimization - autonomy level about 75%.

If in my profitability consideration for my 24.5 kWp system...

Such a large system, which exceeds private consumption by multiple times, will initially be less interesting for private individuals. In a few years, a direct sales market based on blockchain will emerge. Then you can trade directly with electricity customers and will not be measured by the price of the electricity exchange.

I very much hope that some kind of subsidy continues, otherwise the photovoltaics market will collapse quite strongly, with all consequences.

The photovoltaics subsidy in Germany with an almost indecently high return was initiated by Environment Minister Trittin. He knew that the financial attractiveness had to be enormous in order to pay for an enormously expensive good sales force. Why so much? The industry was to grow very fast and become competitive so that in the event of a change of government it would not be abolished again by lobby influence through the blacks. That succeeded. Today photovoltaics is profitable.
An excellent example of a finally successful subsidy policy. I would now wish for this for fuel cells and hydrogen as energy carriers.
Many thanks, Mr. Trittin.

Accusing the Schwarze of lobbying influence that would have destroyed photovoltaics again, and at the same time praising a politician who attends the Bilderberg Conference But this is not a political forum here.

With rather low self-sufficiency, one should also not forget the partially already offered new system of the Solar-Cloud (a kind of virtual electricity storage). Feeding your photovoltaic electricity into the cloud in summer and drawing from the grid for free in winter.
That is why I am still of the opinion that all possible roof surfaces of single-family houses / garages etc., which are suitable up to a certain efficiency level, should be covered with photovoltaics.

Bookstar was talking about a new subsidy that is needed. It is not needed at all, as hampshire wrote.

On the contrary, the return (paid by the citizens through the Renewable Energy Act) is in my opinion even too high. It was 8.5% for me in 2019, before taxes and without taking energy consumption into account. You must be crazy not to install panels on your own roof. I would gladly take your 24 kWp

Come on. The Dax returns on average 14% p.a. over such a period. So you might as well pack up your panels on the hut, which will later be hazardous waste.

Photovoltaics are not profitable enough. It’s fine that there are enthusiasts and people who think the technology is cool. But from a return perspective, it doesn’t pay off.

In case of rather low self-sufficiency, one should not forget the partially already offered new system of the solar cloud (a kind of virtual electricity storage). Feeding your photovoltaic electricity into the cloud in summer and drawing from the grid free of charge in winter.

How is that supposed to work technically? In my opinion, these are purely electricity contracts with deliberately opaque conditions. Nothing is actually stored.

If one sees the community as a "cloud," I would agree with you. But for that, you don't need contracts. Photovoltaic electricity that you don't use yourself is not lost. Therefore, storage or optimizations for self-sufficiency have so far not been ecologically sensible.

That’s why I still believe in covering all possible roof surfaces of single-family houses / garages, etc., that are suitable up to a certain efficiency level, with photovoltaics

I agree. Thanks to subsidies, it pays off for you personally, even though others use your electricity.