Dc power is inherently lossy compared to ac power when sent down a long wire.
Mixing different solar panels in series.
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.
For solar panels connected in parallel total power is calculated as follows.
The parallel connection allows to increase the current keeping the same voltage.
Mixing different capacity panels will reduce total wattage output.
Nonetheless it is possible to wire them in parallel.
In it for the long haul.
Properly done yes you can parallel the panels for more current.
Another option is to take multiple solar panels and wire them together to equal the same output as the other mismatched panel.
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.
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.
A failure at any point in the series will shut the entire system down.
Both must have a diode or both not have a diode and some kind of external power control to protect the battery.
Both panels within a few hundreds of a volt.
In short must be the same voltage.
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.
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.