3R subpanel

[SAP]

I mounted a 3R subpanel on the back of my ground mount solar array. There is strut from post to post hung my equipment sub Contracter does no want me using calking to plug the existing holes in back of my 3 R subpanel what kind of subpanel does not have those existing holes in the back, any ideas how I can plug those holes thank you

 

[Jim1959]

Bolts with washers on both sides works pretty good.