The silicon solar photovoltaic panels on my roof are still there and generating after more than ten years. Do have a look to check yours just in case you want somebody to give them a wipe and do the gutters while they are up there. Most types newer than 15 years have a non-stick coating which is self-cleaning when rained on. The ones on my roof at 40 degrees slope have never needed anything doing. On top of my shed, I tried putting up two more perfectly horizontal solar panels, which was not such a great idea because horizontal collects dust and needs a wipe once a year. I used plain water from the rainwater barrel and a sponge.
The inverter in my attic did stop working at year 7, which was obvious from the meters downstairs failing to go up as usual on a sunny day. You should budget for possibility of that happening. Suppose that you opened a save every month account with one of the banks which pays a little bit of interest and allows very few withdrawls per year without penalty. That should be the right place to drop your savings from having solar, and is available for you to deal with any other sudden replacements, for example the washing machine; whichever needs it first.
I got a replacement inverter of a better design than the original one and swapped it in. That is not for the fainthearted though - most people would ask any qualified electrician capable of swapping in a new cooker to do most of the work. There was a country code mentioned in the small print in the instruction manual which I would not expect a kitchen electrician to find. If you pay extra for someone with 'MCS', you are paying for them to know about things like that.
Trees and obstructions :
Do look at any shadows of trees and where they fall on your roof. A tree can grow a lot in ten years and get in the way of generating.
Two of my neighbours cut down their trees eventually, for being too big and too near their houses.
Sunny day one off performance testing : write here if you'd like a step by step which you can do quite easily.
Routine servicing : No
Budget for major inverter swap : preferable to stash a few hundred pounds of savings ready for that. It will safely stop generating if anything needs doing.