YES-H-PY-01 This Pyranometer is designed for field measurement of global solar radiation ( 400-110 nm) in agricultural, meteorological, and solar energy studies. The YES-H-PY-01 features a silicon photovoltaic detector mounted in a fully cosine-corrected miniature head. Current output, which is directly proportional to solar radiation, is calibrated against a primary standard pyranometer (Eppley Precision Spectral Pyranometer under natural daylight conditions in units of watts per square meter ( W m-2). Under most conditions of natural daylight, the error is <5%). The spectral response of the YES-H-PY-01 does not include the entire solar spectrum, so it must be used in the same lighting conditions as those under which it was calibrated. Therefore, it should only be used to measure unobstructed daylight. It should not be used under vegetation, artificial lights, in a greenhouse, or for reflected solar radiation.