SGR4 pyrgeometer is an instrument for the highest quality scientific measurements. The specially designed meniscus dome provides a 180° field of view with negligible directional response error. A hard-carbon coating on the outside of the dome smoothes the spectral response and provides extra protection to the silicon surface. The excellent thermal stability of the dome construction and coupling to the instrument body eliminates the need for dome temperature measurements or dome shading. SGR4 can be fitted with the CVF4 ventilation unit to further improve its performance. The SGR4 has an internal desiccant that will last for at least 10 years. This minimizes maintenance significantly. The interval for dome cleaning can be extended, and the quality of measurements maximized, by fitting SGR4 with the CVF4 ventilation unit. The SGR4 has Modbus® interface, amplified analogue output, improved response time and temperature corrected measurement data. The long-wave net- and downward radiation are directly available over Modbus®. The wide and low power supply range from 5 to 30 VDC makes integration in meteorological and solar energy stations easy. The SGR4 is extremely robust and comes with 5 years warranty. Thanks to standardized output and connections of every SGR4, exchanging instruments for recalibration is easy. SmartExplorer Windows™ software for data logging, display of data and Modbus® address setting is provided as standard.