I don't think the SPP6e has a polarity setting, thus it doesn't matter which way it connected. It's been years since I installed mine and I'm not climbing on the roof to check, but I remember making a bigger deal out of it than necessary too. It's worked perfectly for my setup, on shore power or generator. I never checked amp draw, but I did note that voltage drop was much less and much shorter. The compressor comes on line almost instantly now. Before there was a definite lag, and you could literally hear the strain.
I'm very satisfied with my setup, however I can see why people are so hesitant to go that route in this current landscape.
