The RSR100, Rotating Shadowband Radiometer, offers a lower-cost option for providing solar measurements, GH, DIFF, and DNI. The RSR100 system utilizes the fast response time of a Li-Cor photocell diode (10 ?sec) coupled with the burst measurement (up to 2 kHz), control, and processing capability of a Campbell Scientific data logger to measure GHI and DIFF solar irradiance and compute DNI.