CSD3 Sunshine Duration Sensor
The Kipp & Zonen CSD3 is a solid-state sunshine duration sensor that uses three photodiodes with specially designed diffusers to detect when direct solar radiation exceeds the WMO's 120 W/m² sunshine threshold, with no moving parts and built-in heaters to shed rain, snow and frost.
- Range
- Spectral range 400 to 1100 nm
- Output
- Sunshine signal 1 ±0.1 V when direct radiation > 120 W/m²; analogue output 1 mV/W/m²
- Supply
- 12 VDC

Overview
In detail
How it works
The CSD3 has no moving parts. Its three photodiodes and diffusers make an analogue calculation of when direct radiation is above the WMO's 120 W/m² sunshine threshold; the calculated direct irradiance value is also available as an output. The sensor runs from 12 VDC and has built-in heaters to dissipate rain, snow and frost, normally switched externally but with an optional internal thermostat.
Installation
Unlike sensors that need a sun-tracking mount, the CSD3's design lets it be fixed in a permanent position to record sunshine.
Maintenance & connectivity
A humidity indicator shows clearly when the drying cartridge needs changing, and a larger screw makes the cartridge easier to replace at extended intervals. A waterproof plug-and-socket cable connection simplifies installation and servicing.
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Specifications
Technical specifications
- Range
- Spectral range 400 to 1100 nm
- Operating temperature
- -40 to +70 °C
- Output
- Sunshine signal 1 ±0.1 V when direct radiation > 120 W/m²; analogue output 1 mV/W/m²
- Accuracy
- >90% of monthly sunshine hours; >90% of direct signal for clear sky
- Supply voltage
- 12 VDC
- Response time
- < 1 ms
- Non-stability
- < 2% change per year
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