After the last post, I monitored the charging system and battery more closely to see if changing the angle made any difference...

It had not.

As mentioned I thought I had got the angle wrong again, so I decided I needed to make adjustments. I used the principle that something pointing directly at the sun casts its shadow directly below itself (it looks like there is no shadow at all). My tri-square has an edge that is nominally square so it will stand perpendicular to the surface it is on.

I chose 11:30 as the panel doesn't face fully south and went up to the roof, put the square on the panel and bent the long brackets to reduce the height until the shadow cast by the tri-square had entirely disappeared.

We will have to see how this has improved the situation.

Pictures to come, I forgot to take them when I was up there.