Very neatly fitted brackets!
How rigid are they, they seem to hold the rails on quite a long lever? I'd be mostly worried about lifting forces with the panels mounted so high up near the ridge.
Pity you'll probably have to take them down again next year when you come to put the further 2.something kW on. With the same type of bracket, you'd have to take almost all slates off. Maybe a good time to add loads of insulation

Klaus
The brackets are quite rigid, I don't think there's going to be any problems, this is why I haven't committed for bigger project just yet.
If I decide to expand the system I will have to take panels down and rest of the slates, quite a few people renovated their roof in the area, but slates are still in good condition, just need membrane replaced... Insulation already done with 50mm celotex. BTW, today meet a contractor re-doing roof in the neighborhood, asked them to remove some slates undamaged so I have some spare next year.