See Installation Report from six years ago.
I have had no generation problems apart from a couple of breaker cut outs.
The annual output has been constant.
The investment return has been about 9%, lower than was suggested but much as I expected as the facing is not due South.
One unfortunate snag was that after several years the roof below them started to sag. I called in the builders who installed joists in the loft that better distributed the weight and, ahem, plastered over the cracks. So far, all is now well.
The ongoing effect has been to wipe out my electricity bill with around £20 a month to spare.