Solar Panel 100 W Regulator

If the output of the two regulators is DC then you could diode-or the two regulators, like this: Be sure to get diodes with enough ampacity, also Schottky diodes have a low forward voltage drop, making them very efficient for this. Make sure to watch the total power dissipation in the diodes, you will need a heatsink.

a lot of assumptions would have to be made to provide a response here.
is it a voltage regulator, current regulator or both? make / model? specs of solar panel?
type of load?
could be that the existing unit will work fine for you if you have not increased your load.

What is the wattage of the solar panels, and what is the load/ application? If you are using the solar panels to charge a battery, usually you can just hook both regulators, with one solar panel per regulator, to the battery without problems and they will self-regulate the current delivered to the battery. If the solar panels are small enough that your single regulator can handle both of them at once, then you can use the diode-or method described by ccr500r to connect them both to the regulator. Be warned that you will lose a significant amount of the power from your solar panels in the diodes, and you definitely need to make sure the diodes are large enough and well heat- sinked.
I'm not quite sure whose regulator you are using, so the above advice may not be applicable to your specific system. Generally, with smaller systems like this using low cost ( Thanks in advance,