SPN1 Sunshine Pyranometer

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Testimonials

"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 Sunshine 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. 

The SPN1 Sunshine 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.  The SPN1 Sunshine Pyranometer design is protected by patents EP 1012633 and US 6417500.

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. Visit the SPN1 Resource Centre.

Direct and Diffuse Radiation

The SPN1 Sunshine 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. The SPN1 Pyranometer 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 Sunshine 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 Sunshine 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 Sunshine Pyranometer.

Applications

The SPN1 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 Sunshine Pyranometer for measuring Total Optical Depth

Over the last 2 years Prof Victor Estelle’s Solar Radiation Research group at the University of Valencia has been running an SPN1 alongside Cimel and Prede sun photometers to see how it compares with these higher precision but more complex instruments.  Preliminary 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 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 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 Sunshine 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 summarised in the document: “SPN1 Pyranometer Performance including BF5/SPN1 Comparison” – downloadable from the SPN1 Product Resources section (menu button above).

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

Specification

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

 Resolution  0.6 W.m-2 = 0.6 mV
 Range  0 to >2000 W.m-2
 Analogue output sensitivity  1 mV = 1 W.m-2
 Analogue output range  0 – 2500 mV
 Sunshine status threshold  120 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 coefficient  0.02% per °C (typical)
 Temperature range  -40 to + 70°C
 Stability  Recalibration recommended every 2 years
 Response time  100 ms (typical)
 Spectral response  400 – 2700 nm
 Spectral sensitivity variation  10% (typical)
 Non-linearity  < 1%
Tilt response Negligible
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 sealing IP67
Sunshine status output No sun = open circuit
Sun = short circuit to ground
Power requirement 2 mA (awake ),  <30 µA (asleep)
5 V – 15 V DC
Heater power 12 V – 15 VDC, up to 1.5 A
RS232 connector 5-pin M12
Signal output & power-in connector 8 pin M12
Mounting options 3 x M5 tapped holes in base at 108 mm dia, 120° spacing
Size & Weight 126 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

Software

Manuals

FAQs

Product Comparisons

Regulatory Information