SPN1 All in one solar irradiance sensor.


The SPN1 complete solar irradiance sensor is a pyranometer, sunshine duration sensor and pyrheliometer all in one complete package. The SMP1 has been specifically designed to accurately measure three key irradiance parameters:

  • Global Horizontal Irradiance (GHI)
  • Diffuse Irradiance (DIF)
  • Sunshine Duration

Using the data from the above three parameters it is possible to accurately calculate Direct Normal Irradiance (DNI) without the use of a pyrheliometer or sun tracker.

Download SPN1 data and fact sheet.



The SPN1 is a complete solar irradiance sensor designed to capture data on solar irradiance which can be used to determine or calculate, direct normal irradiance, global horizontal irradiance, diffuse irradiance, and sunshine duration.

The revolutionary design has no moving parts and does not require shading rings or motorised sun-tracking instruments. As such, no maintenance or shadow ball alterations are required; making the SPN1 ideal for long-term meteorological observations and measurements.

See how the SPN1 complete solar irradiance sensor works in Delta-T’s video.

The SPN1 Pyranometer is ideally suited to multiple solar radiation measurement application areas, including PV (photovoltaic) efficiency monitoring, air pollution studies, cloud cover research, ET and heat flux studies, canopy analysis, and building energy management systems.


SPN1 Specifications

ISO: Secondary Standard
WMO: High Quality
ISO: First Class
WMO: Good Quality
SPN1 Notes
Response Time ISO & WMO <15 s <30 s 0.1 s To 95% of final value (Actual response time is 100ms)
Sero off-set response ISO & WMO 7 W/m² 15 W/m² <3 W/m² To 200 W/m² net radiant loss to the sky (ventilated(
Zero off-set response ISO & WMO ±2 W/m² ±4 W/m² <3 W/m² For 5+A5:F7°C/hr change in ambient temperature
Resolution WMO ±1 W/m² ±5 W/m² 0.6 W/m² Smallest detectable change
Non Stability ISO & WMO ±0.8% ±1.5% <1.5% Change in sensitivity per year
Non-linearity ISO & WMO ±0.5% ±1% ±1% Deviation from sensitivity at 500 W/m² over 100 to 1000 W/m² range
Directional response ISO & WMO ±10 W/m² ±20 W/m² 20 W/m² Error due to assuming that the normal incidence response at 1000 W/m² is valid for all directions
Spectral selectivity ISO (0.35-15 µm)
WMO (0.30-3.0 µm)
±10% (0.4-2.7 µm) Deviation of the mathematical product of spectral absorptance and transmittance from the mean
Temperature Response ISO & WMO ±2% ±4% ±1% Error due to 50°C ambient temperature change
Tilt response ISO & WMO ±0.5% ±2% ** Deviation from horizontal responsivity due to tilt from horizontal vertical at 1000 W/m²
Achievable uncertainty ISO & WMO 3%
95% confidence level
** Believed to be <2%, not yet clearly measured.

Read Delta-Ts short paper if you want to know how s SPN1 compares to a state-of-the-art sunphotometer. 

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