The state-of-the-art TSP-700 Total Solar Pyranometer uses platinum resistance thermometers to make high accuracy broadband irradiance measurements and replace older thermopile measurement  technology. The instrument offers an excellent cosine response and a high level output signal that is totally independent of ambient temperature changes. When properly characterized, the ventilated TSP-700 meets the requirements for a World Meteorological Organization high class pyranometer (formerly called a secondary standard). YES Models TSP-400 and TSP-100 offer lower cost alternatives for applications that do not require the precision of the TSP-700.