The document describes DC string combiner boxes that provide protection and optional performance monitoring for 1000/1500 VDC solar applications. The boxes offer accurate current readings below 0.15% and precise to 0.5%, and can operate up to 70°C. Optional features include voltage and temperature sensors. The boxes have durable FRP/PC enclosures, connect DC cables from PV modules, and transmit data via Modbus RS-485 or wireless. Models are available with or without string current monitoring in various configurations up to 24 strings.