Combining 2 or more DC sources
Boost or buck them all to the same voltage and then parallel them to a charge controller.

The nice thing about DC is that it's fairly forgiving to design interfaces between differing pieces. There are definitely exceptions, especially when converting between DC and AC, but for the most part it would be fairly trivial to regulate the output of any number of differing solar configurations to a common reference and let physics take over from there.

For that matter, this kind of design can essentially become a charge controller in and of itself. The poor man's way of doing it would be to regulate all power sources to battery voltage and just let it all float on the battery. This is far from optimal charging, but it works.