Photovoltaic systems: What experience have you had?

Of course you can. The 600€ is real. If he didn't have the photovoltaic system, he would have to pay 600€ more on his electricity bill.

If he didn't have the photovoltaic system, he wouldn't get 900€ either... Savings and actually payable euros just must not be mixed up.

The fact is: At the end of the year, 500€ are due. No sign of 0€ energy costs...

And if he pays 500,- with [Photovoltaik] and we, my wife and I, 850,- without any [Photovoltaik] (also with washing machine, dryer, dishwasher, and we don’t sit by candles either, and she also cooks), how is such a [Photovoltaik] fox ever supposed to be worthwhile.

The comparison, however, says absolutely nothing. What is crucial is the comparison of Mastermind "without" vs. "with". Without, he would pay €2000 per year for electricity; with, he pays €500. Thus, he effectively saves €1500 per year, not considering taxes and interest (either paid loan interest or lost credit interest). With these points, somewhat worse. Depending on the purchase price, I don't find that so bad...

Do you calculate this way when building a house, even when using better insulation or a more efficient heating system? With that way of thinking, it will be a tent with an open fire ;-)

You can also calculate only with the feed-in tariff, then the ROI is just under 10 years. Then you still have another 10 years of feed-in remuneration with which it turns profitable :-)

If he didn't have the photovoltaic system, he wouldn't get 900€ either... You simply must not confuse savings and real euros to be paid.

The fact is: At the end of the year, 500€ are due. No sign of 0€ energy costs...

I completely leave out the purchase price anyway.

But if someone here writes that you can achieve €0 energy costs with a photovoltaic system, that is just nonsense.

Everything runs on electricity for me. That's why the seemingly high electricity costs.

However, these include all costs for heating, hot water, and household electricity.

In your case, I assume that in addition to your 850€ electricity costs, there are another 500-800€ heating costs in the form of (gas/oil/pellets).
Depending on the size of the photovoltaic system, you could indirectly cover your heating costs through the income from the photovoltaic system.

And if he pays 500,- with photovoltaic and we, my wife and I, pay 850,- without any photovoltaic system (also with a washing machine, dryer, dishwasher, and we don't sit by candlelight either, and she cooks as well), how could such a photovoltaic fox ever be profitable.