I use VHB a lot for semi structural things. Really good surface prep is key as is sufficient square inches of bracket footprint for the tape strength AND the expected load. Keep in mind there are MANY types of VHB. I have not mounted solar panels with VHB, but if I do on my aluminum roof I would use genuine 3m 5952. This was recommended to me by a 3m VHB guru (after many transferred phone calls to get to the right guy) for heat resistance and best all round adhesion to high energy surfaces — metal, glass, etc.
As others have mentioned seal the edges, and as long as you view the brackets as permanent placements, you could also cover the foot with Eternabond. The bracket will never come off with that combo.