The HT Instruments HT305 Irradiance Sensor is a reference cell for irradiance measurements. The HT305 measures irradiance only when connected to the remote unit SOLAR03 through an in-built monocrystalline cell, and can be used with two different kinds of modules, built according two different technologies:

• MONOFACIAL modules measurement of irradiance only on the module’s front (F)
• BIFACIAL modules measurement of irradiance both on the module’s front (F) and on the module’s back (obtained by reflection from the surrounding environment) by dividing the high back part (BH = Back High) and the low back part (BL = Back Low). In this case, it is necessary to use three HT Instruments HT305 cells.