DC String cables act as a lifeline to the solar PV rooftop system. These cables carry DC power generated from solar PV modules to the inverters.
Various studies have shown DC string cables as one of the major components that fails and causes safety concerns like DC arcing, Short circuit, Fire, etc in a solar PV rooftop project. The commercial share of DC string cables in a project is very less when compared to the share of other items like PV modules and Inverters, but we do cost-cutting by selecting the inferior quality of DC cable or by under-sizing the solar DC string cable.
Why care must be taken in selection and sizing of solar DC string cables?
- Operate at high DC voltages in the range of 600V to 1000V
- Are exposed to UV radiations and harsh environment
- Comes in contact with sharp surfaces of structure or cable trays
It becomes very important to select and size solar DC string cables appropriately. In this article, we will discuss how to select and size solar DC string cable
Properties of DC string cables to be used in solar projects
- Suitabe for DC applications
- UV Resistant
- Double Insulated
- Flexible Multi-Stranded Conductor
- Voltage rating of cable to be equal to more than the PV array maximum voltage
Sizing of solar DC string cables
As per International and Indian best practices, the cable should be sized by considering:
Current Carrying Capacity (CCC)
Voltage Drop (%)