The instrument, besides indicating the presence of sun as required by WMO, measures also direct radiation (SRD), therefore it can be used as a low cost alternative to a pyrheliometer, which use is bound to a solar tracker.
The instrument is available in three versions, which difference depends on the type of output:
LP SD18.1 RS485 MODBUS-RTU output and volt-free contact output (contact closed = SRD >= 120 W/m 2 , contact open = SRD < 120 W/m 2 ) LP SD18.2 RS485 MODBUS-RTU output, analog voltage output 0...1 Vdc, which corresponds to 0...2000 W/m 2 of direct radiation, and digital output voltage (digital voltage output: 1V = SRD >= 120 W/m 2 , 0V = SRD < 120 W/m 2 ) LP SD18.3 SDI- 12 output and volt-free contact output (contact closed = SRD >=120 W/m 2 , contact open = SRD < 120 W/m 2 ) The LP SD18 is equipped with a heating element separately powered and galvanically isolated, which prevents the formation of condensation on the glass surface onto which the sensitive elements are. For harsh climates, the above-mentioned versions are available with a second heating element (option R, LP SD18.xR), which prevents the formation of ice and prevents snow from settling. The instrument does not need any positioning adjustment during the year and it can be installed on a mast or on a proper fixing base (optional). The application fields are multiple: from the agronomy (agricultural science) to the study the growth of crops, to photovoltaic systems for verifying their performance, to building automations for automatic opening/closing of blinds, shutters and, in general, to all those areas where it is necessary to monitor the presence of sunlight.