This is something I've been considering. Not because of "green energy" or "climate change" nonsense, but because of the expected rise in energy costs and probable power grid outage.
I'm sure there are people in this community that have done extensive research about this and I'm humbly asking for opinions from anons about this.
Thanks.
Until recently they just about washed their face over 20 years, but as the cost of electricity gets silly they become better and better.
Couple of things to bear in mind, they DO need cleaning, so ensure you can access them without scaffold. They DO degrade over time and it is NOT 0.5% a year it is at least 1.7% Yes they do need to be facing south, or slightly easterly if you have to be off-south (morning skies are clearer than evenings). Away from the equator, the tilt should be tuned to make the most of winter not summer, so quite tilted.
You will need to replace an inverter over that 20 years, probably.
Unless you are somewhere perfect, it is often less than 800kWh per year per installed kWpeak not the 1200 you sometimes get told by sales people. Especially on average over the 20 years with that degradation.
Good luck, good idea if only for security of supply if you have the money now.