On Saturday, July 9, 2016 at 8:35:16 AM UTC-4, Larry Jaques wrote:
So, my kW of solar panels came in. The frames and z-brackets are
aluminum and the hardware (5/16x2-1/2" lags and 1/4-20 bolts) is 304
stainless. I picked up Unistrut to hold it and it has galvanized
nuts. Will there be hell to pay from electrolysis, and, if so, is
there any way to mitigate it? Rubber discs under the washers?

No, just lightly coat all surfaces with Johnson's wax.