A suggestion, perhaps you should consider using a small battery (ie 1 to 2 ah gell cell) and possibly small charge controller rather than trying to directly power the rig from the solar cells. This will prevent the inevitable deep QSB on your signal resulting from a passing cloud while transmitting.

If the max panel current is not too great compared to the capacity of the battery (ie maybe 10%) then you can easily do without the charge controller for portable operations (ie you are not leaving the panels connected to the battery full-time).

Michael

P.S. If each panel is rated at 300ma (ie 5W) then one panel should be quite sufficient to power a Rockmite. With full sun on my 5W panel I almost break even powering my FT-817 and it draws about 350ma on RX.