In addition to what others have said...
You seem to misunderstand the nature of voltage supplied to PCBs. You're treating them as if they create the voltage drop like series resistors.
They do not.
I used to design BiCMOS circuits. Parts of those circuits were heavily bipolar (in every sense of that word...). Bipolar transistors are not like field effect transistors (FET). We depended on the supplied voltage so we could step it down using diodes and VBE drops as part of the circuit.
In other words, the supply voltage was required by the circuit, not created by the circuit. For example, for those circuits that used a 5VDC supply, you could not put a 100-ohm resistor on the supply line and hook it up to a 6VDC source, then expect 5VDC to appear at the true positive input for the circuit. What was more likely to happen is 2.2VDC and a wholly inoperative circuit.
If you chain those PCBs together as you suggest with the voltage capacity of those panels, I expect them to burn up. I don't know if you need the expensive buck converters — but at the very least you need an appropriate transformer so you can hook all the PCBs together in parallel.