and just in case someone is interested, here are my findings:
- silicon conformal coating: my first try was to coat the board w silicon conformal coating, it worked for a while but when the first rain came my board short circuit (I think the issue was my solar panel connections though which were protected only by some hot glue which probably is porous) - silicon conformal coating leaves your board shiny...
- NeverWet: did 2 coats open boards and the solar panel, leaves an horrible white powder on the boards, thought it was busted after first rain - boards have worked great so far even after 3 days of rain - been working fine for 10 days now and battery seems to stay charged. Thanks again to ChemE for the idea, we'll see how long the coating works...