Up to a point you can but you could quite easily , quickly run into the charging limits of the unit you have.
Taking the EcoFlo Delta 2 as an example.
This power bank has three solar input limits, 500Watts, 15 Amps and 60 Volts. With a warning exceeding the latter can damage the unit. The 500Watts clearly means you can't have both the 15 Amp & 60 Volts limit together, as that's 900 Watts.
Wiring them up has to be considered and what might be a tolerable configuration in dull conditions could do damage should briefly the clouds part and the sun wink at the array.
Much the same logic comes into play with fixing panels and the effect of the suns angle through the day and through the year, what is "safe" at 9am could be unsafe at real noon. What is safe in the low seasons will be way unsafe in the summer.
IMO your best option is to settle for a 500Watt array wired up in series to yield as high a voltage as your panel options give (*) and power bank can tolerate, but in this you need to keep the panels well matched.
Taking the EcoFlo Delta 2 again, and the more readily available panel options, that tends to limit you to two 200 to 250 panels wired up in series to get about 45 volts.
It would be nice if you could better exploit the EcoFlo's 60 volt limit but getting panels with their open circuit voltages up beyond 24 volts, or lower than 20 volts could be challenging.
(*) the higher we can get that notional input voltage from the array, the higher will be our yield under poorer solar conditions and I would suggest that is our real life aim.
We have typically no real challenges on blazing sun days, as campers our real difficulty is getting enough on a series of overcast days.
Unfortunately quite a difference to the solar industries own goals, simply getting the maximum they can, their kit is tailored to that.
I would with my EcoFlo like to have three 167 Watt panels with open circuit voltages of just 20 Volts and optimum output voltages very close to that, so I could get the best available yield on overcast days whilst not risking doing damage on sunny ones.
Your conundrum is one I presently am facing, I have the EcoFlo powered by a Excel Power 200Watt panel but might invest in a second identical panel. I have noticed the EcoFlo , compared to my Morningstar PWM system charging the caravan's battery, does not switch into charge at as lower voltages. So it does not achieve as much in that more critical low light conditions.
I have thought of altering the 200 Watt array's wiring of its two panel from its out of the box parallel to series, just screwing up its 5 year warranty holds me back at the moment. Given a bit of time, better performance during so much of its usage might well be more motivating than being in a possible warranty claim position.
I did discuss this with the supplying dealer but I felt they were missing the underlying logic of the technical argument, we as campers would be better served by arrays that work as well as possibly under low light conditions rather than be extra good under ideal condition. I note now that Excels 440 Watt array does just that, but I could not bring myself round to shelling out the extra money, possibly a poor decision in retrospect though at the time I did not know these finer but important details. ( should have done more homework pre being seduced by the offers at the time!)
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