When sourcing sub meters, you must prioritize Accuracy Class (typically Class 0.5s or 1.0) to ensure precise billing and energy monitoring. Key technical factors include Communication Protocols (RS485 Modbus RTU, M-Bus, or LoRaWAN) for data integration, Current Transformer (CT) compatibility (solid-core vs. split-core for easy retrofitting), and Multi-tariff capabilities to track energy usage during peak and off-peak hours. Ensure the device supports DIN Rail mounting for standard electrical cabinet installation.