The Low-Cost Irradiance Sensor is used to measures the irradiance value for residential and rooftop applications or small-scale projects. The industrial, commercial and utility-scale PV project requires advanced features and high accuracy for meteorological sensors. However, this is not the case for residential and small-scale PV applications. The cost of the sensor should be proportional to scale of the PV system. SEVEN achieved that by Low-Cost Irradiance Sensor. The measured irradiance data are transmitted to monitoring devices, data loggers, and other receiving units via serial RS485 interface with MODBUS RTU protocol.