DC wiring losses are mainly caused by the ohmic resistance of the cabling that interconnects PV devices and strings, although losses can also occur in connections and fuses. The $I^{2}\times&space;R$ power loss varies as a function of the array current squared. Differences in cable length or size among parallel strings can introduce differences in voltage drop, $I\times&space;R$, and therefore contribute to mismatch. Series protection diodes are another source of voltage drop.