AndyGM
Having looked at Bing Aerial Imagery and Esri World Imagery, nothing that resembles solar panels until viewing Mapbox Satellite and Maxar Premium Imagery so there was a point when they weren't there.

Doing a bit of digging I can safely say that they are solar panels

https://www.msn.com/en-gb/video/viral/amazons-largest-depot-in-the-uk-has-been-fitted-with-nearly-6000-solar-panels-to-provide-enough-energy-for-more-than-300-homes/vi-BB1fePgL

https://www.dailyrecord.co.uk/lifestyle/gallery/inside-huge-scots-amazon-depot-25544100

I have added solar panels now > https://www.openstreetmap.org/changeset/114964562