Material certificate

Alloy and temper, traceable to the extrusion batch

Anodising certificate

Thickness in microns, because that is the corrosion life

Structural calculation

The load case, the code, and who signed it

Layout drawing

Module positions, rail runs and fixing centres by zone

Torque specification

Per connection type, for the installer to work to

Torque record

Completed at installation, because it cannot be checked later

Earthing record

Continuity measurements between rails and modules

Warranty statement

What is covered, for how long, and what voids it

An illustrative list for a fictional range. A real programme agrees which documents are required, in what form, and how long they are retained.

The one that is most often missing.

The torque record. It is the only evidence that the connections were made to the specification, it cannot be reconstructed afterwards, and it is the first thing asked for when an array fails.

Why the calculation has to name a signatory.

Because a calculation is only as good as the assumptions in it, and the assumptions are about a specific roof. A document that does not say who checked it against that roof is a template rather than a calculation.