SPN1 Sunshine Pyranometer

    How to Buy
Pyranometer Zoom
SPN1 PyranometerSPN1 PyranometerComputer Generated Shadow Maskspn1 hand – Copy – 1000 x 1000SPN1-for website – 1000 x 1000SPN1 Arctic – small


"The Sunshine Pyranometer (SPN1) is deployed in the Arctic for the MOSAiC campaign as part of the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) IceRad system." Communications Dept,
The Atmospheric Radiation Measurement user facility, U.S. Department of Energy (DOE)
"We bought our first SPN1 by the middle of 2008, as the device seemed at first analysis to be well suited to our needs. We now know it is - and we now have 12 of them, hoping to reach 20 within 2 years." Patrick Jeanty, LE2P lab Research Engineer. Lan Sun Luk. Jean Daniel, Professor in charge of RCI_GS Project. Morgane Barthod & Aude Zuliani, Master trainees.
Energy, Electronics and Process Laboratory Université de la Réunion, Saint-Denis
  • Global (Total) and Diffuse irradiance in W.m-2
  • WMO sunshine threshold: 120 W.m-2 direct beam
  • DNI (Direct Normal Irradiance) calculations
  • Sunshine status
  • No moving parts, shade rings or motorised tracking

The SPN1 Pyranometer is a precision solar radiation measurement instrument with a ground glass dome, and is designed for long-term outdoor exposure. It is an affordable and effective alternative to shade-ring pyranometers, pyrheliometers and traditional sunshine recorders.

Video – Introduction to SPN1

The SPN1 Pyranometer is exceptionally easy to use; it needs no routine adjustment or polar alignment and works at any latitude.

An internal heater keeps the pyranometer dome clear of dew, ice and snow down to -20°C (in still air conditions), ensuring reliable readings in difficult climatic conditions.

SPN1 Pyranometer Resource Centre

The Resource Centre contains a wide range of application and technical information for the SPN1 – covering DNI calculation, tilt correction, performance validation, and much more. Visit the SPN1 Resource Centre.

Direct and Diffuse Radiation

The pyranometer uses an array of seven miniature thermopile sensors and a computer-generated shading pattern to measure the direct and diffuse components of incident solar radiation. It computes direct radiation by subtracting the diffuse from the global (total) radiation.

Sunshine Duration

The WMO threshold for bright sunshine is 120 W.m-2 in a plane perpendicular to the direct solar beam. The SPN1 Pyranometer uses an algorithm based on the ratio of direct to diffuse radiation, combined with their absolute values, to estimate sunshine duration to within a few percent of the WMO standard.

The SPN1 Pyranometer does not need to be adjusted or repositioned to track the sun – a distinct advantage over devices with shadow rings. There are no complex electro-mechanical assemblies and no burnt paper tracks to interpret.

Outputs and logging

The SPN1 Pyranometer provides 2 analogue voltage outputs for global and diffuse radiation, and a digital output for sunshine duration, which can be connected to data loggers, such as the Delta-T Devices GP2 and the compact GP1.

Readings can also be obtained directly from the RS232 port and viewed/logged using the SunData software supplied.

The GP1 Data Logger from Delta-T Devices is a powerful general purpose data logger that provides a low cost logging solution for the SPN1 Pyranometer.


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. For further information please visit the SPN1 Resource Centre.

opticaldepth2-18022016143517Evaluation of the SPN1 Pyranometer for measuring Total Optical Depth

Prof Victor Estelle’s Solar Radiation Research group at the University of Valencia has been running an SPN1 Pyranometer alongside Cimel and Prede sun photometers to see how it compares with these higher precision but more complex instruments. Their findings indicate a relatively good correspondence – scientific posters were presented at Skynet Rome 2016 and EGU Vienna 2016.

Download Application Note here

Calculating DNI

Direct-Normal Irradiance (DNI) is the amountmcl-15-05-2012-08-54-44 of solar radiation arriving in unit time at the Earth’s surface on a unit area perpendicular to the direction to the Sun. It is a common practice to compare solar panel efficiency to DNI, particularly in field trials. Output from an SPN1 Pyranometer allows calculation of DNI in sun tracking, horizontal and tilted installations.

Read more about the SPN1 Pyranometer and DNI Calculation in the “SPN1 Technical Fact sheet“.

There are two ways to calculate DNI:

1) DNI Firmware: The SPN1 Pyranometer can calculate DNI (requires firmware version 1.08 or later). The results are only available on the Serial output and requires the use of a Terminal program or similar to send RS232 commands and receive the results. For more information download Use of the DNI Function in SPN1 Firmware. To upgrade the SPN1 firmware to the required version 1.08 contact techsupport@delta-T.co.uk

2) DNI Spreadsheet: You can download an Excel spreadsheet add-in to calculate DNI from the output of a horizontally mounted SPN1 Pyranometer, using data logged from either the analogue or serial outputs. Download the spreadsheet here.

SPN1 Pyranometer – comparison with BF5 Sunshine Sensor

The SPN1 Pyranometer is a precision version of the BF5 Sunshine Sensor and although the two instruments have some features in common, there are important differences. These are explained in the Summary of differences between the SPN1 and BF5 technical note.

Please note that research literature sometimes refers to the SPN1 Pyranometer as the SPN1 Radiometer.



For simultaneous outputs of total radiation, diffuse radiation and sunshine status.

Overall accuracy: Total (Global)
and Diffuse radiation

±5% Daily integrals

±5% ±10 W.m-2 Hourly averages

±8% ±10 W.m-2 Individual readings

Resolution0.6 W.m-2 =0.6 mV
Range0 to >2000 W.m-2
Analogue output sensitivity1 mV=1 W.m-2
Analogue output range0 – 2500 mV
Sunshine status threshold120 W.m-2 in the direct beam

Accuracy: Sunshine status±10% sun hours with respect to the threshold
Accuracy: Cosine correction±2% of incoming radiation over 0-90° Zenith angle
Accuracy: Azimuth angle±5% over 360° rotation
Temperature coefficient0.02% per °C (typical)
Temperature range-40 to + 70°C
StabilityRecalibration recommended every 2 years
Response time100 ms (typical)
Spectral response400 – 2700 nm
Spectral sensitivity variation10% (typical)
Non-linearity< 1%
Tilt responseNegligible
Zero offsets< 3 W.m-2 for a change of 5°C/hr in ambient temperature
< 3 W.m-2 dark reading
Latitude capability-90° to + 90°
Environmental sealingIP67
Sunshine status outputNo sun=open circuit
Sun=short circuit to ground
Power requirement2 mA (awake ), <30 µA (asleep)
5 V – 15 V DC
Heater power12 V – 15 VDC, up to 1.5 A
RS232 connector5-pin M12
Signal output & power-in connector8 pin M12
Mounting options3 x M5 tapped holes in base at 108 mm dia, 120° spacing
Size & Weight126 mm dia. x 94 mm high, 786g

Product Resources

Additional resources can be found at the SPN1 Resource Centre. The Resource Centre contains a wide range of application and technical information – covering DNI calculation, tilt correction, performance validation, and much more.

Data Sheets

Case Studies





Technical Notes

Product Comparisons

Regulatory Information