Photovoltaic system: Advantages and disadvantages, experiences, worthwhile?

Or a photovoltaic system over three roof sides without changing the size of the system? Does something like that make sense in terms of effort if you stay under 10 kWp?

I can confirm from my own experience. Our system ran nicely evenly from morning to evening (was somewhere between 7 and 8 kWp).

Three orientations are unfavorable because typical inverters can only handle 2 strings, and one string is needed per orientation. The efficiency loss due to heat is not that dramatic. Typically, modules lose 4% performance per 10°C temperature increase. Ultimately, you have to build on the existing roof anyway. If you can position it freely, you can of course optimize. Best to play around with POVGIS and experiment. Modules have recently become significantly cheaper again. This further reduces the disadvantage of E/W systems.

Or a photovoltaic system over three roof sides without changing the size of the system? Does that make sense in terms of effort if you stay under 10 kWp?

As I said, you always have to see what the inverter can do. We have a single-story bungalow with a 35° roof pitch facing southeast and southwest, so rotated 90°. The roofing will have to be renewed in the next few years anyway. Then we will install a few kW of modules on both surfaces. The installation itself is not that difficult, only connecting to the grid requires an electrician.

We have a 45° gable roof with East(South)/West(North)... but it is slightly rotated, so that the double number of panels is on the East side. I also try to make sure that the washing machine and dishwasher run when there is enough steam, but without overdoing it. Total consumption for 3 people was just under 2300kWh in 2018... but I generated half of that myself.

Just checked again. Out of 2100 kWh consumed in 2018, we generated about 900 ourselves. So about 42%. But 2018 was also a very good year...

We have an angled bungalow with a 35° roof pitch facing southeast and southwest, so rotated 90°. The roof covering will need to be renewed in the next few years anyway.

That sounds like a nice roof for photovoltaics!