The same voltage is the system voltage which for off grid solar panels systems is usually as low as either 6v or 12v.
Different voltage solar panels in parallel.
If we have two solar panels with the same voltage but different wattage there is no problem.
So a 12v and 24 volt panel hooked in series will produce about 36v when connected to a load.
It has anode and cathode the one marked with single line.
That is the positive of one to the negative of the other.
So if you wired the same panels from before in parallel the voltage of the system would remain at 40 volts but the amperage would increase to 10 amps.
If you want to connect diode on positive of your panel choose the anode of your diode.
It is possible to connect 2 solar panels of different voltage output in parallel.
This will prevent reverse voltage damage so that the higher voltage panel will not destroy the lower voltage panel.
If the two panels have similar current ratings but different voltage rating you can put them in series to get the sum of the voltages at the single current rating.
Connecting solar panels in parallel is just the opposite of series connection and is used to increase the total output current of the array and hence the total output power while keeping the same voltage.
On the other hand if our two solar panels have both different wattage and different voltage then parallel connection is not possible since the panel with the lowest voltage would behave like a load and would begin to absorb current instead of producing it with the relative consequences.
Lets say the load is a 24v water pump.
If you connect 2 solar panels of different voltage in series or in parallel 1st let consider 2 in series.
Wiring solar panels in parallel causes the amperage to increase but the voltage remains the same.
Mostly the higher voltage panel will deliver most of the current and the low voltage panel does little.
Then you get the sum of the two.
Putting the two dissimilar panes in parallel is not a good idea.