Mixing different capacity panels will reduce total wattage output.
Mixing different solar panels in series.
The parallel connection allows to increase the current keeping the same voltage.
When connecting modules of dissimilar electrical characteristics in series it is each module s current that plays a heavy role in how the string is going to perform in the solar power system.
Matched voltage even better.
When mixing solar modules is important to remember that it is not the wattage of the modules that is important to consider.
Both panels within a few hundreds of a volt.
Though mixing different solar panels is not recommended it s not forbidden and things would be ok as long as each panel s electrical parameters voltage wattage amps are carefully considered.
In short must be the same voltage.
Nonetheless it is possible to wire them in parallel.
Mixing solar panels in parallel total connected power 150w 150w 150w 150w 600w unlike connection in series if among modules connected in parallel there is a module of power output lower than the output of the other modules this might not affect seriously the total power output of the array provided that this module has equal to the other modules rated voltage.
Properly done yes you can parallel the panels for more current.
Now if you do have two different solar panels two different sizes the best solution with charging a single battery bank is for each of them to have their own charge controller.
For solar panels connected in parallel total power is calculated as follows.
Dc power is inherently lossy compared to ac power when sent down a long wire.
In it for the long haul.
Total connected power 140w 150w 150w 150w 590w unlike solar panels connected in series the different wattage parameters do not effect the overall outcome of the array.
Both must have a diode or both not have a diode and some kind of external power control to protect the battery.
Another option is to take multiple solar panels and wire them together to equal the same output as the other mismatched panel.