From HeatSpring.com PV Boot Camp Discussion Board
I understand that resistance is a constant since it is tied to a material's properties, but you said that Ohms Law measures voltage drop or loss and I don't see that in the law.
Ohm's law states:
V = I x R
The V is going to be the voltage drop and not the system voltage.
If we have 2A, a 3 Ohm wire and a 100V system, then:
Vdrop = I x R
Vdrop = 2A x 3 Ohms = 6 Volts
Then if we want to figure out voltage drop percentage:
6 volts of voltage drop / 100V system = 6% voltage drop.
Let me know if you need more.