Solar / Photovoltaic from an economic perspective

How would it behave if the solar thermal system is also applied to the underfloor heating? It will bring nothing in winter. But it should cover the transitional period.

You then need at least 2 additional panels and a larger buffer storage, which in turn increases the costs, and in winter you have to heat the large buffer storage with gas.

This is how it looks...in the transition period hardly any yields are to be expected...in winter none at all...

That's how it looks... hardly any yields are to be expected during the transition period... none at all in winter...

I think then the concept has to be different. The system must then not be optimized for the summer optimum, but rather for the optimum in the transition period or winter. That means the solar panels are installed, for example, at a steeper angle to have the optimal angle for the low sun and to be as snow-free as possible. (See "Sonnenhaus"). Whether it will pay off at some point, I have no idea.

The efficiency of the system decreases over the years, ....

That's what I mean... and that the inverter and the cells are due after a little more than 10 years is practically certain... there are plenty of examples

Hm - manufacturers usually provide a 20-25 year performance guarantee for the modules. To my knowledge, an annual percentage deduction is applied for this. I would have to check my documents, but I seem to remember that the deduction over 20 years was a maximum of 20%. Thus, a module failure as described by should be a warranty case – although I currently don’t have the exact terms at hand (but presumably neither do you).

btw: Of course, damage can always occur that makes a replacement necessary. Whether it happens and how severe the impact will be depends partly on how the respective product is treated/handled, as well as on "random chance."

At least we have already gotten through the first year well. Let’s see, maybe in 9 years I’ll report on the status and whether a part of the system has to be scrapped.

Well, the warranty is unfortunately of little to no use because most manufacturers have declared bankruptcy after 5-6 years... Thus, you get no more and no less than the legally mandated 2 years of warranty...

Well, unfortunately the warranty is of little to no use because most manufacturers have declared insolvency after 5-6 years... So you get no more and no less than the legally mandated 2-year warranty...

Well, I can be glad that my manufacturer (Viessmann) is still active and that its primary business is not in the photovoltaic sector. There is a chance that in the worst case I will still benefit from the 25-year warranty.