Ok, I have updated the pcb layout with bridges for the rx/tx lines and also fixed that vcc was missing on the gps IO_line, from my pevious tests this system works fine with just 6 of the smalles solar cells (19x38) connected in series to vcc, there is no need for any fancy boost/buck/ converter, ldo or to solder a supercap to the board, it will moste likley with this simple setup have a startup at around 10-12° solar angle if you set brownout on the 328 to 1.8V.
there would be great to incorperate a reset function from pin 9 on the gps to the 328 to pull low once every 10 min to reset the gps
Mikael
