Economics of Photovoltaics - My Findings - Is Something Missing?

: Thanks for your comment! It would be more accurate as follows:

[*]The most worthwhile for private houses is usually photovoltaic systems with a peak output just under 10 kWp. (Above that, it only becomes worthwhile again from 13-14 kWp due to the Renewable Energy Act surcharge, for which very large roof areas are required. Sometimes you have to stay below 10 kWp due to lack of roof space.)

I find it interesting...

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The financing costs are tax-deductible. With a 3% loan and a marginal tax rate of 42%, only effective interest of 1.74% remains. And the installment can easily be paid by the monthly earnings of the photovoltaic system.
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Does this also apply in the context of an overall financing where the photovoltaic system is included/budgeted in the house financing?

If you can somehow separate that, I would try it. The tax office can do no more than say no.

Example: 200,000 loan, of which 10,000 euros for the photovoltaic system = 5%

So I would allocate 5% of the interest costs to the photovoltaic system as an expense. I wouldn't know what speaks against that. It's no different with proportional operating expenses if you don't split the loans.

The tax advisor takes care of the details...

If you can somehow separate that, I would try it. The tax office cannot say no more than no.

Example: 200,000 loan, of which 10,000 euros for the photovoltaic system = 5%

So I would allocate 5% of the interest costs to the photovoltaic system as an expense. I don’t see what would speak against that. It’s done in the same way for proportional operating costs if you don’t split the loans.

The tax advisor takes care of the details...

Since construction is done with individual trade assignment, the photovoltaic offer (11,960€ gross for 8.82 kWp) is available. So separation should not be a problem, I think.

This means, if I use the loan with 20 years fixed interest, I can deduct the interest costs of 3,131€ for tax purposes every year over 20 years + of course also the depreciation?

Please ask your tax advisor what you can deduct, when, how, and where. The interest costs do not seem implausible overall to me, but of course, you can only deduct the interest that has actually accrued proportionally each year. Since it is probably annuity repayment, there are many interest payments at the beginning and fewer at the end.

Interest (and loan) for the value-added tax only applies if you do not reclaim the VAT and operate as a small business. Otherwise, be sure to exclude the VAT. But the tax advisor will handle that as well.

Ideally, you deal with the matter yourself because with that little money, a tax advisor is not worth it.