Part Two: DC Losses
DC Cable Losses
DC Cable Losses
Wiring Losses
Suggested Values for Wiring Loss:
- 2% wiring loss for most systems
- 1% if using thicker wires or very short runs
Several components can cause a voltage drop in circuits, including connections, fuses, and resistors. Differences in cable length or size among the parallel strings can also introduce a voltage drop.
NREL’s study “Performance Parameters for Grid-Connected Systems” is a widely cited source of loss factors. They suggest a 2% loss for DC wiring. Systems with shorter wire runs between the modules and inverter, or with thicker wire may see a loss closer to 1%.
DC Cable Losses
Connection Losses
Suggested Loss Value: 0.5% according to the NREL Study
PV connection losses come from wiring connectors and diodes. Most solar panels contain bypass diodes, which let other modules on a string circumvent a panel that is shaded or otherwise performing poorly. These components have a small voltage drop, caused by the internal resistance of the material and imperfections in the contact surface.
