mrbd

I had a rotary meter in one house that went backwards when it was sunny and I "didn't notice" so it never got reported. It was a risk of discovery if the meter reader chap was to see it going backwards, or if we had a really good summer and a meter reading was less than the previous one. When I moved house I was glad to see another rotary meter, do I duly installed some solar panels. But alas it was slightly newer and had the above-mentioned ratchet. I think there was a cut off date in the late eighties/ early nineties when they started installing these. So there really is a dwindling pool of meters that run backwards and I suspect with the proliferation of smart meters they will be a thing of the past.

My thoughts are that an additional test could add value and it's something I plan to do, probably with a DIY fan.

Agreed

You seem to have two DC isolators in series on each string? Be careful because although a DC isolator might have 4 poles, the internal links need to remain and are there by design to break the DC arc. I suspect that it should be 1 dedicated DC isolator per string. Can you share the wiring diagram /SLD from the electrical design? Or better still a photo of the inside wiring of the DC isolators with the covers off? I'm concerned that if you operate a DC isolator under high irradiance it could risk a fire.