The relationship between the voltage loss and the cable in the photovoltaic system can be seen from the formula: voltage loss = passing current * cable length * voltage factor. The voltage loss is proportional to the length of the cable. Therefore, the principle that the array to the inverter and the inverter to the grid-connected point should be as close as possible should be followed during field surveys. Generally, the DC line loss between the photovoltaic array and the inverter does not exceed 5% of the output voltage of the array, and the AC line loss between the inverter and the grid connection point does not exceed 2% of the output voltage of the inverter. The cable voltage drop formula can be used in the engineering application process: △U=(I*L*2)/(r*S)

       △U: cable voltage drop（V）

       I: The cable needs to withstand the maximum cable（A）

       L: Length of cable laying（m）

       S: the cross-sectional area of the cable（mm²）

       r: Conductivity of conductor-m/（Ω*mm²), r copper=57, r aluminum=34