Is the solar system on the roof worthwhile?

It’s also more about being forced to do something here. And a VAT return in 5 minutes, please show me that

Sorry, that was exaggerated, it’s actually just one click in the accounting system. VAT returns are so trivial (collected VAT vs. paid VAT, simply put), no one prepares them anymore, they are generated and transmitted from the month’s bookings.

I’ll give you an example: According to the fee schedule, a tax advisor may charge a minimum fee and minimal matter value (€650 - you’ll never reach that with photovoltaics) of €6.80 net for a VAT advance return.
An equivalent annual VAT return with minimum fee and minimal matter value (€8,000 - also far too high for photovoltaics) costs €86.
Furthermore, with such low turnover, a monthly advance return should no longer be required after the first year at the latest, but only an annual one. However, I don’t have the exact limits in mind right now.

The maintenance of the heating system can indeed be claimed for tax purposes (under certain conditions and not unlimited, of course).

Yes, that's correct. But to a significantly lesser extent. The maintenance of the photovoltaic system is completely net, unless one wants (and is able) to opt for the small business regulation, and additionally reduces the profit and thus income tax, solidarity surcharge, and, if applicable, church tax.

It’s more about being forced to do something here. And a VAT return in 5 minutes, please show me that

I’m happy to confirm that the monthly VAT advance return (monthly VAT return is nonsense) does not take 5 minutes. I have been doing it for about 15 months now and would even go so far as to say that 5 minutes is pessimistic. More like 3 minutes.

And usually, after a year, the tax office agrees to only have the return submitted quarterly at most, or most likely not at all anymore.

Then there’s only the annual VAT return and income tax return (which everyone should do anyway, for other reasons).

I didn’t want to start a tax discussion here [emoji85]

The threshold for small business owners is €17,500 revenue (not profit) per year. $19 Umsatzsteuergesetz

The effort is actually not high. You calculate the depreciation once at the beginning with Excel. It’s worth making the effort once because it makes sense to depreciate declining balance first and only later switch to straight-line depreciation.

Otherwise, there really isn’t much paperwork. Expenses are rare. Maybe something for maintenance or if cleaning is required or something like that. That doesn’t happen every month and is not frequent.

Then I believe the energy providers usually bill revenues once a month. So, just one sheet.

The likelihood that revenue exceeds €17,500 is rather low for photovoltaics for "own use". Therefore, you register right away as a small business, so the submission obligation is automatically annual, and the advance VAT return and declaration are unnecessary. Likewise, advance payments are not an issue.

Under these conditions, the effort is actually low. You don’t have to take anything to a tax advisor; everyone can manage this on their own at home.

You just have to remember how it must be handled because some people are not aware of it.

Five years ago I dealt with the topic with a colleague who wanted to install photovoltaics on his house. At that time, he calculated that it almost pays off simultaneously with the time it needs to be replaced. The financial benefit is barely or not at all there, especially if you include your additional effort calculated with an hourly wage.

Ten years ago I calculated it with my boss out of interest. We came to the same conclusion. Back then, I think it was very well subsidized; I don’t know how strongly it is subsidized today...

Experience from x years ago is worthless because the market is highly dynamic. Just last year alone, prices for photovoltaics fell by 10%, and the previous years do not look much different. On the other hand, the feed-in tariff changes. Yield forecasts are also individual and of course important in order to determine the ROI.

Man meldet daher eh sofort als Kleinunternehmen an, somit ist die Abgabepflicht automatisch jährlich, die Umsatzsteuervoranmeldung und -Erklärung erübrigt sich. Ebenso sind Vorauszahlungen kein Thema.

One definitely does not immediately register for the small business regulation because they want to deduct the VAT from the investment. However, for this, you have to pay VAT on self-consumption. After 5 years, if you remain under the turnover limits, you can switch to the small business regulation if you consider it sensible. You have to calculate that.

Experiences from x years ago are worthless because the market is very dynamic. Just last year, prices for photovoltaics fell by 10%, and previous years look much the same. On the other hand, the feed-in tariff is changing. Yield forecasts are also individual and of course important to determine the ROI.

The comparison can certainly be quite interesting. My father-in-law invested about €12k in a photovoltaic system nearly 10 years ago. With the feed-in tariff at that time and the compensation for self-consumption, he earns about €1200 per year. We will now also pay about €12k for our system and earn about €1200 with today's feed-in tariff. The systems differ greatly. He has 3-4 kWp, we have 9.9. Still, the return on investment has changed little. I will write something separately about the general aspects.